RE: SI Unit for volume
ANSI?? This is the same organization that has reinvented the well-proven ISO-metric fastener standard and in the process, came up with the M6.3 screw. What is a 6.3mm screw you ask? Why it's ¼ of course! Another gem of their wisdom is they reinvented the traditional flat topped DIN 85 screw head (the best design of a slotted screw head ever made), and came up with a new improved slotted screw head (ANSI IFI-513) that has rounded edges and as a result causes a screwdriver blade to easily torque out of the slot when tightening. One wonders if they have gotten to reinventing the wheel yet. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chuck Mullett [mailto:chuck.mull...@onsemi.com] Sent: June 21, 2002 9:15 AM To: richwo...@tycoint.com Cc: emc-p...@majordomo.ieee.org Subject: Re: SI Unit for volume Yep, cubic meters, of course. Don't forget to separate the value from the unit: 15 m3. Folks often omit the space between the 5 and the m. ANSI will punish! Chuck Mullett richwo...@tycoint.com wrote: Nevermind. I found the answer to be cubic meters. -Original Message- From: WOODS, RICHARD Sent: Friday, June 21, 2002 8:28 AM To: 'emc-pstc' Subject: SI Unit for volume When stating a cubic volume in SI units, is liters the correct unit. If not, what is the correct method of expression? Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: SI Unit for volume
Sorry, you're right. I had meant mW/cc, not W/cc. Until recently Ferroxcube and others had listed their ferrite's hysteresis losses (as a function of frequency and flux density) in terms of mW/cc. Then suddenly their new datasheets changed to KW/m^3. My first reaction was that they must be crazy to apply these enormous units to a ferrite core, a dozen of which would fit in the palm of one's hand! But it quickly became obvious that these units were actually the same as the old mW/cc. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: TM66 [mailto:t...@rcn.com] Sent: June 21, 2002 11:12 AM To: Robert Wilson Subject: Re: SI Unit for volume Bob, W/cc is multiple of KW/m^3. 1 KW = 1,000 W and 1 m^3 = 1,000,000 cc therefore: 1 KW/m^3 = 1,000 W/1,000,000 cc = 0.001 W/cc or 1 W/cc = 1,000 KW/m^3 Robert Wilson wrote: ... For example, in the latest Ferroxcube ferrite core catalogue, specific values of core hysteresis losses are given in KW per m^3 of ferrite material, even though these are the same units as W/cc. ... Regards, Mirko Matejic --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: SI Unit for volume
Only if it applies to fluid volume. If it applies to volume of a solid, then it is traditional to use cubic centimeters, or even m^3. The latter is a heck of a big volume, and sounds almost silly, but it is increasingly used. For example, in the latest Ferroxcube ferrite core catalogue, specific values of core hysteresis losses are given in KW per m^3 of ferrite material, even though these are the same units as W/cc. Liters are never mentioned or ever used in this context. Context seems to be important, so the units used should make sense when considering what the units apply to. A non-metric example of something that makes no sense is how American companies are now rating air compressors in gallons per minute. This is really absurd since all tools that are powered by compressed air sold in the US are rated in CFM, the gallons/minute rating is useless. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: June 21, 2002 5:28 AM To: emc-p...@majordomo.ieee.org Subject: SI Unit for volume When stating a cubic volume in SI units, is liters the correct unit. If not, what is the correct method of expression? Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Slotted Busbars
I cannot say if it is acceptable, because I am not sure what your particular criteria for acceptability is. But I can say that there is no problem technically. In the company I previously worked for, we designed and made telco rectifiers (basically they are honking big 48V battery chargers). Each rectifier outputted 10KH, and there were 11 of them per rack cabinet (for a total of 110KW per cabinet). At the top of each row of cabinets there was a pair of rather large bus bars connecting the outputs of each cabinet in parallel. I'm not talking about a puny 400A here; average continuous current was 10,000 A, and peak current could reach 100,000A for a short time when clearing a fuse (in this case the batteries under charge supplied the current peak). The bus bars were all laminated from thinner material (1/4 thick x 6 wide copper bars). They were peppered with obround holes (i.e. slots with rounded ends) to make bolt alignment easier. There was no problem at all, nor can I imagine why there should be. The only problem I can possibly see would be if rectangular slots (with sharp corners) were used. I could see someone complaining about this causing stress concentration and possibly being a start for crack generation. But I doubt that this is the problem you are referring to, since only a rank amateur mechanical designer would use a sharp-cornered rectangular slot for bolt clearance. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: David Sproul [mailto:david.spr...@alexanderlynn.co.uk] Sent: June 21, 2002 2:12 AM To: EMC-PSTC Subject: Slotted Busbars Dear Group, I have a client who wishes to use open slots instead of closed holes for the connecting bolts used in joining two 400A busbar within their product. This decision was taken to make installation and maintenance easier. However, their installation Manager has objected to this without giving a reason. I have e-mailed my contacts within TUV and UL, and after some 48 hours they have not responded. Are there any sufficiently knowledgeable people who can tell me whether or not this is permissible, and why. Best regards, David Sproul.
RE: magnetic field measuring instruments and probes
Assuming the sensed current in the coil is reasonably sinusoidal, skin depth at 100KHZ is about half the diameter of AWG 28, (if the winding is only one layer thick). This means that the entire wire cross sectional area will be carrying current. This was my reason for suggestion that particular wire size. Actually, given the very small level of induced current (probably microamps or less), it really makes no difference at all what wire is used. Even AWG 14 will do the job nicely since even though only the skin of the larger size wire will be carrying current, there will still be far more actual effective conducting area than is needed for such a miniscule current. It's not like this is a high power switchmode power supply transformer, or something like that, where current density in the wire is high and minimizing eddy current losses is critical. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: June 20, 2002 6:31 PM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: Re: magnetic field measuring instruments and probes I was simply reporting the military standard construction. I haven't done the analysis to determine skin effects and whether using Litz wire to counter it is useful. -- From: Robert Wilson robert_wil...@tirsys.com To: emc-p...@majordomo.ieee.org Subject: RE: magnetic field measuring instruments and probes List-Post: emc-pstc@listserv.ieee.org Date: Thu, Jun 20, 2002, 5:06 PM Litz wire at 100KHz sounds a little over the top. AWG20 or 30 will do the job nicely. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: June 20, 2002 7:11 AM To: Istvan Novak; emc-p...@majordomo.ieee.org Cc: Istvan Novak - Board Design Technology Subject: Re: magnetic field measuring instruments and probes At the low end you could use a 13 cm loop such as that used for military RE01/ RE101 testing (36 turns of 7-41 Litz wire, electrostatically shielded). That loop can be used from 30 Hz to at least 100 kHz. It is handy because it is small and can be used as a probe. There are numerous loops developed for VDE testing that operate from 10 kHz to 30 MHz. But these loops are physically large and developed for use at 3 meters from the test item. There are also close field probes for diagnostic testing, but these have large antenna factors. So the answer depends on your specific need. -- From: Istvan Novak istvan.no...@worldnet.att.net To: emc-p...@majordomo.ieee.org Cc: Istvan Novak - Board Design Technology ino...@pompom.east.sun.com Subject: magnetic field measuring instruments and probes List-Post: emc-pstc@listserv.ieee.org Date: Thu, Jun 20, 2002, 7:28 AM Hi list members, Could someone suggest or refer me to pointers/manufacturers of probes and instruments to measure magnetic close field in the 10kHz to 10MHz frequency range? High accuracy is not important, values to be measured would be around 0.5mT and up. Thanks Istvan Novak SUN Microsystems
RE: Transient Voltage Suppressor - Europe approvals?
Agreed. But not all the devices you mention operate in the same way. In particular, Sidactors get their high apparent energy absorption because they crowbar the line being protected, to relatively near ground potential. They are basically energy-rated bidirectional breakover diodes (acting like self-triggered triacs). Thus, although the device handles high spike current, the voltage across it is very low during this period (thus power dissipation in the device is much lower). Devices operating off the AC line being protected by a sidactor, will see an interruption in their power supply (the AC line), as a result of the sidactor clamping it to near-zero volts. Because of the Sidactor's crowbar action, it is not likely acceptable as a normal AC line protection device (they are more commonly used to protect data and telecom lines). A transzorb or a MOV simply limits the rise of voltage to a small increment ABOVE nominal line voltage, hence the power dissipation will be much higher than with a Sidactor. But the benefit is that devices operating from the protected AC line will see no interruption in their power when a hit occurs. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: j...@aol.com [mailto:j...@aol.com] Sent: June 19, 2002 9:51 AM To: Robert Wilson; mpet...@analogic.com; emc-p...@majordomo.ieee.org Subject: Re: Transient Voltage Suppressor - Europe approvals? In a message dated 6/19/2002, Bob Wilson writes: Transzorbs (or TVSs) are basically zener diodes that are rated for their energy absorption capability. Hello All: One thing to keep in mind is that the energy handling capability of a TransZorb is generally not very high compared to other devices such as gas tubes, MOV's, and sidactors. Michael, your original posting did not specify the intended application, but the reference to being rated for mains voltage makes me wonder if you are trying to protect from surges on an AC mains input. If so, I do not think that a TransZorb would have adequate energy handling capability. Joe Randolph Telecom Design Consultant Randolph Telecom, Inc. 781-721-2848 http://www.randolph-telecom.com
RE: Transient Voltage Suppressor - Europe approvals?
Transzorbs (or TVSs) are basically zener diodes that are rated for their energy absorption capability. Since they are polar devices (i.e. diodes) they are useless on an AC line. Well, I suppose you could put two of them back to back, but this is not at all common. Typically, these devices are used to protect lower voltage DC busses. Higher voltage (line voltage) AC lines are most commonly protected by varistors (e.g. ZnO types). Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Peters, Michael [mailto:mpet...@analogic.com] Sent: June 19, 2002 6:33 AM To: 'emc-p...@majordomo.ieee.org' Subject: Transient Voltage Suppressor - Europe approvals? Greetings, Is anyone aware of Transient Voltage Suppressors (General Semiconductor calls them TransZorbs) with any European safety approvals (Semko, Demko, VDE, etc.,)? They would need to be rated for mains voltage. Thanks, Michael Peters --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: vibration test system
Perhaps you should provide some details such as expected load, frequency range and so on. One should expect that one's choice of equipment and manufacturer will be different if one is shaking a military tank, than if one is shaking a small electronic module, for example. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Wani, Vijay (V) [mailto:vw...@dow.com] Sent: June 17, 2002 1:48 PM To: 'emc-p...@majordomo.ieee.org' Subject: vibration test system hello Group: I am planing to buy vibration / shock test system for our lab. and basically, looking for Vibration Research, Ling Dynamic System (LDS) and Unholtz Dickie Corp. for the system (electrodynamic shaker, controller, analyzer). I would appreciate any input / recommendation / experience on vibration test system for their performance. thank you in advance. vijay wani (989)636-0473 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Magnetics testing
The only problem is that a utility transformer may have high energy density, but it has little more flux density than the smallest wall-wart. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Scott Douglas [mailto:dougl...@naradnetworks.com] Sent: June 14, 2002 10:06 AM To: emc-p...@majordomo.ieee.org Subject: Re: Magnetics testing Lisa, Gee, could you maybe talk to your local power company and set up inside one of their local distribution stations? With all those transformers, high voltages and currents, I would think 80 gauss would be easy to find? Scott At 11:13 AM 6/13/02 -0500, Ken Javor wrote: I don't know labs who does this kind of work, but I don't think the original request is that out there. I think more info is needed (at least by me). If this is at 50/60 Hz, I don't think it is that bad. Looks like around 100 Amps would be necessary. Not your typical Helmholtz coil, but not outside the bounds of reality. Depends a lot on the size of the test item. If it is small compared to a breadbox, then the 100 Amp number could come down substantially. -- From: Mike Cantwell mike.cantw...@flextronics.com To: emc-p...@majordomo.ieee.org Subject: RE: Magnetics testing Date: Thu, Jun 13, 2002, 9:08 AM 30 to 80 Gauss is equivalent to about 6500 A/m. This is an enormous field!!! Do you have the right units? -Original Message- From: lisa_cef...@mksinst.com [mailto:lisa_cef...@mksinst.com] Sent: Thursday, June 13, 2002 6:40 AM To: emc-p...@majordomo.ieee.org Subject: Magnetics testing Hello All, I am wondering if anyone knows of a test lab in the northeast capable of generating a magnetic field strength of 30 to 80 Gauss? thanks Regards, Lisa Lisa A. Cefalo, CRE Manager, Reliability and Design Services MKS Instruments (978)-975-2350 X 5669 lisa_cef...@mksinst.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at:
RE: Shielded DC Power Cable Vendors
In other words you are suggestion to cure the disease itself, and not just the symptom. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: JP Hare [mailto:john.p.h...@verizon.net] Sent: June 13, 2002 4:50 AM To: Anchondo, Dan; emc-p...@majordomo.ieee.org Subject: RE: Shielded DC Power Cable Vendors Hi Dan, I saw your previous post and was wondering if it would receive any attention. As I recall, you are trying to shield a 200A DC power cord. I am assuming you want a shielded cable because of radiated EMI problems. Usually shielded power cords are not theoretically sound solutions for EMI reduction. Do you control BOTH ends of this cable? I imagine you control the EUT end, but allow the other end to be connected to the standard CO power bus. If this is true, then you are essentially extending the noisy cable to the bus bar and into the CO's power system. The RBOC may have a problem with this. If you have considered this and you still believe that a shielding strategy is acceptable for you, you may want to make your own shield from flat braided ground strap. I've seen certain types that open up into a tube. You may be able to fit this around your cable assembly. Obviously the best solution is to filter the energy. But I realize that finding and implementing a 200A filter could be a bit difficult! A closer look at the DC-DC converters may be necessary... Good luck, Paul Hare jphar...@earthlink.net -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Anchondo, Dan Sent: Wednesday, June 12, 2002 8:44 PM To: emc-p...@majordomo.ieee.org Subject: Shielded DC Power Cable Vendors All Looking for vendor that provides shielded DC power cables. Regards Dan Anchondo --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: (off topic) Stirling cycle
Best use of a Stirling engine I have seen, was implemented by a friend of mine in Germany about 15 years ago. He added a miniature Stirling engine he had made (it could be held in one's hand) to his butane powered barbecue grill. The heat of the grill drove the Stirling engine, which in turn operated a rotisserie. So as the meat was turning, one could hear the little Stirling engine quietly chugging away. Very clever, those Germans! :) Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ted Rook [mailto:t...@crestaudio.com] Sent: June 10, 2002 1:50 PM To: Subject: (off topic) Stirling cycle Chris, what is the Stirling cycle? short tongue in cheek reply: a well kept secret! in truth it is an external combustion engine which uses the thermal expansion and contraction of gas to produce motion. typically the system is sealed, there is a 'hot' end and a 'cold' end, The energy input in the form of the temperature differential can be extracted as work from a piston and crank. Alternatively put work into the shaft and you can maintain a temperature differential.. try searching the web for Stirling cycle the amount of information available has increased significantly in the past year or so there is hope :-) I believe people under estimate the incoming energy that penetrates the cloud cover. I don't have figures but I think long wave infrared reaches the ground through clouds. It can be focused by solar collectors. The oil/gas/electricity utilities and their PR departments would like us to believe we are helpless and dependant on their massive infrastructure. I believe they make sure we have the limitations of photovoltaic cells and rechargeable batteries rammed down our throats to discourage independent thinking. Electrolysis, fuel cells, flywheels, solar collectors, stirling engines, wind and wave power, all are coming and will be usable on a small scale by individual households. I plan to power/heat/cool my residence with solar energy and disconnect the utility lines in the foreseeable future. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: DOC Assembled from tested components
Seems to me that the court could better use its time to nail some of the el-cheapo products from the far east made by manufacturers that just stick a CE mark on everything they make as part of the graphics design. I have seen numerous such products that haven't a hope of getting CE approval, proudly wearing a CE mark. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: June 10, 2002 11:29 AM To: emc-p...@majordomo.ieee.org Subject: RE: DOC Assembled from tested components Ken, a UK court ruled that CE+CE does not equal CE. They fined at least one PC reseller because they integrated and sold PCs based upon the belief that CE+CE=CE. Obviously, the court thought otherwise. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Gonzalez, Kenneth P (Rocky) [mailto:kpgon...@ingr.com] Sent: Monday, June 10, 2002 12:20 PM To: emc-p...@majordomo.ieee.org Subject: DOC Assembled from tested components All, Has anyone successfully issued a DOC using the assembled from tested components method for a personal computer? I have not been able to find a floppy disk drive manufacturer that has any DOC documentation for their device; even the ones marketing directly to home users. Have I just not found the right manufacturer? Best regards, Rocky -)-(- Kenneth P. Gonzalez (Rocky) Intergraph Solutions Group Integrated Products Division 170 Graphics Drive Madison, Alabama, USA 35758 phone (256) 730-2131 fax (256)730-2424 kpgon...@ingr.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: IEC 60950 Solar Cells
On the surface, it seems to me that that requiring any sort of regulatory compliance for a device operating from a 3 Volt source would be utterly absurd. But then, from my perspective, regulatory agencies are not always noted for their use of common sense in creating their regulations. The fact that solar cells are used as a power source should be irrelevant. There would be no functional difference between operating from a 3V battery and a 3V solar cell. The only reason I could imagine that regulatory controls could extend their all-controlling tentacles into this issue is if the 3 Volt source was internally converted into much higher voltages, or you are generating potential EMI. But that, too has nothing to do with the product using solar cells. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: June 6, 2002 3:26 PM To: emc-p...@majordomo.ieee.org Subject: IEC 60950 Solar Cells To all, First, a little background. I have been asked a question that I did not know the answer to, which relates to a potential new product. As I understand it, this device will be relatively small, consume very little power and will only display particular information depending on the application. What I have been told, this device will be powered by a solar cell with a potential 3V coin battery for back up (the battery part is iffy). I can't give anymore information about it because I don't know any more. Now, to the questions. As the scope of IEC 60950 3rd Edition or IEC 60950-1 applies to equipment that is powered up to 600V, it would seem that the standard would apply to this product. However, I cannot find a single reference to a solar cell energy source. Would a solar cell energy source be treated similarly to a battery? Would this small LCD display device even be required to be evaluated to IEC 60950 3rd Edition or to IEC 60950-1? As always, I look forward to your insightful replies. Best regards, Ron Pickard rpick...@hypercom.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: ferrite transient voltage/current response
Heat is the obvious source of the problem. But what causes the heat, how hot does the ferrite get, and what is the rate of change of temperature? Clearly, permanent magnetization of the ferrite is simply irrelevant here, since by definition, the soft ferrites used to make beads and cores cannot be permanently magnetized. The flip side of that is that hard ferrites (which CAN be permanently magnetized, and are used to make magnets) are useless for making ferrite beads and cores. Self heating due to an imposed alternating magnetic field will continue to generate heat until the material's Curie point is reached. At this point, the ferrite looses its magnetic properties, and no further heat is generated due to hysteresis losses. But with many ferrites, the Curie point is over 200°C. It seems possible that this temperature level could cause cracking, IF the rate of change of temperature was extreme. Temperature alone will not cause either cracking, or changes in material properties. After all, ferrites are made by a firing process that is FAR hotter than a mere few hundred degrees! But in the manufacturing process, temperature is ramped up and down slowly, to eliminate any possibility of thermal shock. So you are probably right that observed effects are due to the ferrite becoming cracked. The reason for cracking cannot be due to temperature by itself, but rather to an extreme rate of change of temperature. Excess energy applied too fast, for the volume of ferrite used, is the cause of the excessive rate of change of temperature. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: June 6, 2002 11:06 AM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: Re: ferrite transient voltage/current response Then why would a 10 A surge change their characteristics? Unless it cracks it? - Robert - -Original Message- From: Robert Wilson robert_wil...@tirsys.com To: Robert Macy m...@california.com; emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Thursday, June 06, 2002 8:51 AM Subject: RE: ferrite transient voltage/current response Soft Ferrites cannot be permanently magnetized. This is precisely why they are used as beads and cores. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: June 5, 2002 11:20 PM To: don_borow...@selinc.com; emc-p...@majordomo.ieee.org Cc: shbe...@rockwellcollins.com Subject: Re: ferrite transient voltage/current response He may have magnetized it. Degaussing with one of those Radio Shack thingies would probably brought it back. Can he try it again? - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: don_borow...@selinc.com don_borow...@selinc.com To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org Cc: shbe...@rockwellcollins.com shbe...@rockwellcollins.com List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, June 05, 2002 2:52 PM Subject: RE: ferrite transient voltage/current response While I was at Agilent in Spokane, one of the engineers or technicians claimed that he had changed the RF characteristics of a 6-hole ferrite bead (wound with 2 1/2 turns) used on a power supply trace to a noisy assembly. The normal current was about 1 amp, but he accidently shorted the power supply voltage after the inductor. This caused a current spike as the power supply filter capacitor discharged (and then the supply current limited at about 10 amps). After this, there was a problem with RF leakage from the assembly. Replacing the inductor fixed the problem. Apparently the effect was repeatable. I didn't observe this personally, so I can't guarantee it. Don Borowski Schweitzer Engineering Labs Sorry that I wasn't clear; I typically try to keep my questions general so not to get too detailed about the specific application. And thanks to Bob, Chris and Mike who have responded ... putting it into Chris's words ... I was just trying to find out if ferrites had ratings to prevent them from j ust plain blowing the ferrite to smithereens. Also, I was looking for a shortcut if someone else had faced this question rather than reading through all of the vendor web sites. I understand and have used ferrites quite often for typical EMI suppression; the ferrites typically being rated for the application currents, voltages, etc. In this case, the program is trying to protect a power supply input from the DO-160 waveform 5B pin injected lightning pulse of 300 volts open circuit 300A short circuit. If the Gas Discharge Tube is located past (closer to the supply which was done for packaging limitations
RE: ferrite transient voltage/current response
Soft Ferrites cannot be permanently magnetized. This is precisely why they are used as beads and cores. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: June 5, 2002 11:20 PM To: don_borow...@selinc.com; emc-p...@majordomo.ieee.org Cc: shbe...@rockwellcollins.com Subject: Re: ferrite transient voltage/current response He may have magnetized it. Degaussing with one of those Radio Shack thingies would probably brought it back. Can he try it again? - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: don_borow...@selinc.com don_borow...@selinc.com To: emc-p...@majordomo.ieee.org emc-p...@majordomo.ieee.org Cc: shbe...@rockwellcollins.com shbe...@rockwellcollins.com List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, June 05, 2002 2:52 PM Subject: RE: ferrite transient voltage/current response While I was at Agilent in Spokane, one of the engineers or technicians claimed that he had changed the RF characteristics of a 6-hole ferrite bead (wound with 2 1/2 turns) used on a power supply trace to a noisy assembly. The normal current was about 1 amp, but he accidently shorted the power supply voltage after the inductor. This caused a current spike as the power supply filter capacitor discharged (and then the supply current limited at about 10 amps). After this, there was a problem with RF leakage from the assembly. Replacing the inductor fixed the problem. Apparently the effect was repeatable. I didn't observe this personally, so I can't guarantee it. Don Borowski Schweitzer Engineering Labs Sorry that I wasn't clear; I typically try to keep my questions general so not to get too detailed about the specific application. And thanks to Bob, Chris and Mike who have responded ... putting it into Chris's words ... I was just trying to find out if ferrites had ratings to prevent them from j ust plain blowing the ferrite to smithereens. Also, I was looking for a shortcut if someone else had faced this question rather than reading through all of the vendor web sites. I understand and have used ferrites quite often for typical EMI suppression; the ferrites typically being rated for the application currents, voltages, etc. In this case, the program is trying to protect a power supply input from the DO-160 waveform 5B pin injected lightning pulse of 300 volts open circuit 300A short circuit. If the Gas Discharge Tube is located past (closer to the supply which was done for packaging limitations) than the T EMI filter, a question was raised as to whether the ferrite properties would be altered by the lightning pulse. Most of the standard literature on the use of ferrites does not address these types of transients. Susan Beard Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on 06/04/2002 02:16:48 PM Please respond to Robert Wilson robert_wil...@tirsys.com Sent by:owner-emc-p...@majordomo.ieee.org To:shbe...@rockwellcollins.com, emc-p...@ieee.org cc: Subject:RE: ferrite transient voltage/current response Your question is not all that clear. It appears to imply that transients have an affect on the ferrite beads, but it is the other way around (maybe that is what you meant). But in general, small ferrite beads have little effect, except at very high frequencies (hundreds of MHz), unless they are no longer beads (i.e. they are very large). Have a look at the various magnetics vendors data sheets and app notes. Magnetics Inc: www.mag-inc.com Fair-Rite Inc: www.fair-rite.com (whoever came up with THAT name should be shot! Steward Inc: www.steward.com Ferroxcube: www.ferroxcube.com Epcos (was Siemens): www.epcos.com Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com] Sent: June 4, 2002 8:57 AM To: emc-p...@ieee.org Subject: ferrite transient voltage/current response Could someone point me to some good App Note information on the response of and affect on ferrite beads to transient voltage current waveforms? The waveforms are based on the indirect lightning pulses specified in Section 22 of DO-160. Thanks in advance, Susan Beard This e-mail may contain SEL confidential information. The opinions expressed are not necessarily those of SEL. Any unauthorized disclosure, distribution or other use is prohibited. If you received this e-mail in error, please notify the sender, permanently delete it, and destroy any printout. Thank you. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel
RE: ferrite transient voltage/current response
Heat buildup in a ferrite is self-limiting. Once temperature reaches the material's Curie point, it looses its magnetic properties, and heat buildup essentially stops. Mind you, this temperature can be as high as 200°C for some power ferrites, so it may get rather toasty. There is no actual rating as such, that I am aware of because there are far too many variables. Hysteresis heating can be estimated from the usual curves of specific power loss-vs-excitation frequency-vs-flux density that most manufacturers provide for each material. But this only tells you how much heat is being generated due to hysteresis losses. It still won't tell you the heat generated by resistive losses in a lossy type of ferrite (which is what is commonly used for this purpose). It also won't tell you what the thermal resistance of the ferrite is (i.e. how easily it can lose the heat being generated). The latter is sometimes available for ferrite E-E cores (and other transformer shapes), but for small beads, I suspect there is nothing available. Finally, a lot depends on the harmonic content you are hitting the ferrite bead with, and this is obviously impossible for a ferrite manufacturer to know. The answer, I suspect, is to try it. At least, the thing will not blow itself to smithereens, but it might get mighty hot before it hits the self-limiting Curie point. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com] Sent: June 5, 2002 10:09 AM To: emc-p...@ieee.org Subject: RE: ferrite transient voltage/current response Sorry that I wasn't clear; I typically try to keep my questions general so not to get too detailed about the specific application. And thanks to Bob, Chris and Mike who have responded ... putting it into Chris's words ... I was just trying to find out if ferrites had ratings to prevent them from j ust plain blowing the ferrite to smithereens. Also, I was looking for a shortcut if someone else had faced this question rather than reading through all of the vendor web sites. I understand and have used ferrites quite often for typical EMI suppression; the ferrites typically being rated for the application currents, voltages, etc. In this case, the program is trying to protect a power supply input from the DO-160 waveform 5B pin injected lightning pulse of 300 volts open circuit 300A short circuit. If the Gas Discharge Tube is located past (closer to the supply which was done for packaging limitations) than the T EMI filter, a question was raised as to whether the ferrite properties would be altered by the lightning pulse. Most of the standard literature on the use of ferrites does not address these types of transients. Susan Beard Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on 06/04/2002 02:16:48 PM Please respond to Robert Wilson robert_wil...@tirsys.com Sent by:owner-emc-p...@majordomo.ieee.org To:shbe...@rockwellcollins.com, emc-p...@ieee.org cc: Subject:RE: ferrite transient voltage/current response Your question is not all that clear. It appears to imply that transients have an affect on the ferrite beads, but it is the other way around (maybe that is what you meant). But in general, small ferrite beads have little effect, except at very high frequencies (hundreds of MHz), unless they are no longer beads (i.e. they are very large). Have a look at the various magnetics vendors data sheets and app notes. Magnetics Inc: www.mag-inc.com Fair-Rite Inc: www.fair-rite.com (whoever came up with THAT name should be shot! Steward Inc: www.steward.com Ferroxcube: www.ferroxcube.com Epcos (was Siemens): www.epcos.com Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com] Sent: June 4, 2002 8:57 AM To: emc-p...@ieee.org Subject: ferrite transient voltage/current response Could someone point me to some good App Note information on the response of and affect on ferrite beads to transient voltage current waveforms? The waveforms are based on the indirect lightning pulses specified in Section 22 of DO-160. Thanks in advance, Susan Beard --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: ferrite transient voltage/current response
Your question is not all that clear. It appears to imply that transients have an affect on the ferrite beads, but it is the other way around (maybe that is what you meant). But in general, small ferrite beads have little effect, except at very high frequencies (hundreds of MHz), unless they are no longer beads (i.e. they are very large). Have a look at the various magnetics vendors data sheets and app notes. Magnetics Inc: www.mag-inc.com Fair-Rite Inc: www.fair-rite.com (whoever came up with THAT name should be shot! Steward Inc: www.steward.com Ferroxcube: www.ferroxcube.com Epcos (was Siemens): www.epcos.com Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: shbe...@rockwellcollins.com [mailto:shbe...@rockwellcollins.com] Sent: June 4, 2002 8:57 AM To: emc-p...@ieee.org Subject: ferrite transient voltage/current response Could someone point me to some good App Note information on the response of and affect on ferrite beads to transient voltage current waveforms? The waveforms are based on the indirect lightning pulses specified in Section 22 of DO-160. Thanks in advance, Susan Beard --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Japan mains voltage
In designing power supplies, it is common to use nominal mains voltage +/-15% (e.g. in North America, 115 +/-15%, or 98V to 132V) as a design guideline. The same +/-15% is generally true for European 230 V designs. Thus, using +/-10% for Japan seems a little skimpy. Given the rather odd collection of voltages, line frequencies and power systems in use there, if it were me, I'd allow for AT LEAST +/-15%. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Van Compernolle, Eric [mailto:eric.vancomperno...@barco.com] Sent: June 4, 2002 8:22 AM To: 'emc-p...@ieee.org ' Subject: Japan mains voltage Hello, As you probably know the mains voltage for Japan is 100V. For safety we are testing up to - 10%: 90 V. However for some situations in Japan , it seems you can even expect 85 V. So we are planning to define a general rule that a product for Japan must handle 85 V. Is this low voltage rule known or common use in your company? best regards, Van Compernolle Eric Reliability Manager Barco Projection Systems Noordlaan 5 8520 Kuurne Phone:+32 56 368 373 Fax:+32 56 368 355 mailto:eric.vancomperno...@barco.com http://www.barco.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Bonding to conductive plastic - best method?? - BEST SCREW
Chris, Plastite screws are a good choice where a) only fastening is being done in plastic , and b) there is sufficient boss strength and thickness (since being thread formers, they put significant tensile stress on the screw boss). If it were me, I'd consider a thread cutter such as a standard type BT sheet metal screw. Type BF could also be considered, but there its thread cutting action is done by simple cuts in the thread, and in my experience there isn't enough space for the plastic chips to go as the thread is cut. The BT screw has a nice large scallop at the front that cuts the thread and thus offers some where to accommodate the chips. Type T is similar to type BT, but the thread is much finer, and is not really suited to use in plastic. Cracking is definitely a concern. I have had problems with this in the past when using thread forming screws with less-than-massive screw bosses. Using a thread cutting screw allowed much smaller boss diameter, while still having good holding power. The only real down-side is that one must take a little care not to cut new threads when re-inserting the screw. Conductivity of stainless steel here is of little concern. Even though the screw will have somewhat poorer conductivity than a normal hardened steel screw, you have to remember that the bulk resistance of the screw is only a VERY insignificant contributor to the overall system resistivity. Besides you are using the screw to make contact to even more stainless steel! Nickel plating is nicely compatible with stainless, but there are no sheet metal screws that are made of brass! So if you go the route of using a type BT thread cutting screw, your choices are either plated high carbon steel or high carbon, low-300-series stainless steel. Self tapping screws in general must be hard in order to self tap! Your suggestion of using an (externally) threaded insert is a good possibility. Of course it WILL require (obviously) a larger boss diameter than if you used only a screw alone. I have used inserts with external threads that were thread forming, and also thread cutting in the past. The latter are promoted as not creating excessive tensile stresses in smaller bosses, and in my experience they worked well. Insertion into the plastic is done using an ordinary tapping head on a drill press. I used these some years ago and can try to dig up information on them if you are interested, Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Wells [mailto:cdwe...@stargate.net] Sent: June 4, 2002 5:11 AM To: Robert Wilson; EMC-PSTC Discussion Group Cc: christopherdwe...@eaton.com Subject: Re: Bonding to conductive plastic - best method?? - BEST SCREW Robert - Putting inserts aside for a moment - What do you see as the best screw type? The plastite style high/thin/coarse thread screw we presently use does not appear to cut the plastic as much as it deforms and pushes into the plastic to make the threads. I could be wrong - would a self taping style like used on metal plate have a better performance? Keeping with the plastite style - We have been using about 80% engagement of threads and I have experimented with %100 but am concerned about cracking of the screw boss. Of corse the 100% not only has the thread engagement but the base shaft of the screw as well in contact with the plastic. On plating/base matterial - It sounds like SS screws will be my move but I wonder about the conductivity of SS in general. I take it that nickle plated brass would be uncommon and perhaps would also give a corosion problem. Back to the SS inserts - I will check pricing and availability of a self tapping style screw in insert. Thanks - I think I am getting closer Chris Wells Senior Design Engineer Cutler-Hammer Pittsburgh, Pa. USA 412 490 6862 christopherdwe...@eaton.com
RE: Shielded High current cable
Are those rather irrational AWG sizes even recognized by TÜV or VDE? Most of the rest of the world hasn't a clue what they mean. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Anchondo, Dan [mailto:danch...@ciena.com] Sent: June 3, 2002 11:15 AM To: emc-p...@majordomo.ieee.org Subject: Shielded High current cable All Can anyone point me to a vendor that makes shielded power cable? We require wire that is 2 gauge, DC, 200 amps, normal flexibility, shielded,105 degree C, VW-1,UL,CSA,TUV,VDE certs. Dan Anchondo Ciena CSD --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Bonding to conductive plastic - best method??
The problem you are encountering is made somewhat more difficult by the very low amount of metal in the polycarbonate resin. Reasonable shielding generally requires higher than 20% metal in the mix (35% is not uncommon). But to answer your questions: - The type of screw is relatively unimportant. Any screw that cuts into the plastic matrix, and gets through the insulating resin skin that forms on the surface as a very thin insulating layer, and makes a pressure contact with the stainless matrix will do nicely. - The material the screw is made from is also not particularly relevant from an electrical contact standpoint. Anything will do as well as anything else (at least initially). But in the long haul, a stainless screw is preferred since there will be no galvanic mismatch to cause a corrosion couple. Any plating is NOT a good idea since it will be cut through when the screw is inserted, and your contacts to the stainless fibers will be made mainly to the bared metal substrate of the screw. - The larger the screw the better. There is very little stainless steel in your mix, and you need to maximize tour contact area (or use more stainless filler). - Conductive liquids and pastes are useless in this application. They cannot make significant contact with the metal fibers because there is a microns-thick layer of pure polycarbonate resin on the surface of the plastic (to say nothing about other things like mold release). - Molded-in inserts are not reliable. You need to make a gas-tight metal to metal connection, and for this you need mechanical pressure. -You also must remember that the polycarbonate resin itself (like any polymer) is NOT gas tight, and NOT hermetic. It allows gaseous diffusion over time, and thus any internal connection between a screw and the stainless fiber matrix, must be gas tight (i.e. a high pressure connection) to ensure reliability. Interestingly, a significant mode of conduction BETWEEN fibers is by electron tunneling through the ultra thin layer of resin that separates them. But as a general comment, I suggest you use a polycarbonate blend with a more reasonable amount of stainless fiber. This will obviously improve your shielding, but more importantly it will dramatically improve your contact reliability. Better still, is to use long strand stainless as a filler, which has far better shielding characteristics than finely chopped stainless (if you are not already doing so). Do you need to paint the plastic as a result of the stainless content? Generally, the surface finish of metal fiber-loaded resin is rather ugly, necessitating a final painting for aesthetics. If this is so in your case, then you really ought to consider forgetting about using stainless filler altogether and instead selectively electroless plating the inside instead of painting the outside. This will result on FAR better shielding, and a better looking product. Conductive paints such as Spraylat's non-corroding copper, on the inside will also result in one or two orders of magnitude better level of shielding than the low level of stainless fiber content you are using. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Wells [mailto:cdwe...@stargate.net] Sent: May 31, 2002 7:23 PM To: EMC-PSTC Discussion Group Subject: Bonding to conductive plastic - best method?? - Original Message - From: Chris Wells mailto:cdwe...@adelphia.net To: EMC-PSTC Discussion Group mailto:emc-p...@majordomo.ieee.org Cc: christopherdwe...@eaton.com Sent: Friday, May 31, 2002 8:07 AM Subject: Bonding to conductive plastic - best method?? Recently we had a good string going on conductive platics. I would appreciate some help coming up with the ideal electrical bond to this type of plastic. We use a 6% Stainless Steel Fiber mix in Poly carbonate and I was looking for the best method to electrically bond to the plastic to drain off ESD or for high frequency bonding with the metal portion of our product. This would include Printed Circuit Board to plastic, Cable to plastic and metal housing to plastic type connections. For joining metal housing and PCB connections we have been using plastic screws that mechanically are designed for plastic. The threads are widely spaced, tall and thin - They cut into the plastic with out breaking the mounting bosses (studs). The engagement with the plastic (screw thread in plastic boss hole) is ~ 100% leaving little or no air gap between the screw and the plastic. First set of Question - If using screws what would be the best type of screw to insure good contact to the stainless steel fibers? * High profile, thin thread, plastic screw like I described? * Self tapping type screw? What should the platting be? * Clear Zinc * Zinc Chromate?
RE: Bonding to conductive plastic - best method??
The first of your suggestions will not work with the material Chris is using. Any polymer that has conductive material mixed in, tends to form a thin skin of pure resin at its surface. A conductive paint or epoxy applied to the surface will not come in contact with the metal strands, and all you will mainly get is capacitive coupling. Further, applying a silver-loaded epoxy to the surface of most metals (including stainless steel) will not penetrate that material's natural oxide layer and hence (unlike what most people I've talked to seem to think) will NOT produce a reliable electrical connection, even when applied directly to the metal. A reliable electrical connection to any metal requires that one must cut through the metal's oxide layer. Thus, your second suggestion is more workable, although he is basically using these already (the plastic screws he refers to are very similar to sheet metal screws). Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Jim Conrad [mailto:jc...@shore.net] Sent: June 2, 2002 4:34 AM To: Chris Wells; EMC-PSTC Discussion Group Subject: RE: Bonding to conductive plastic - best method?? Hi Chris, I would try a Silver loaded conductive epoxy or use SS self tapping screws. Jim -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Chris Wells Sent: Friday, May 31, 2002 10:23 PM To: EMC-PSTC Discussion Group Subject: Bonding to conductive plastic - best method?? - Original Message - From: Chris Wells mailto:cdwe...@adelphia.net To: EMC-PSTC Discussion Group mailto:emc-p...@majordomo.ieee.org Cc: christopherdwe...@eaton.com Sent: Friday, May 31, 2002 8:07 AM Subject: Bonding to conductive plastic - best method?? Recently we had a good string going on conductive platics. I would appreciate some help coming up with the ideal electrical bond to this type of plastic. We use a 6% Stainless Steel Fiber mix in Poly carbonate and I was looking for the best method to electrically bond to the plastic to drain off ESD or for high frequency bonding with the metal portion of our product. This would include Printed Circuit Board to plastic, Cable to plastic and metal housing to plastic type connections. For joining metal housing and PCB connections we have been using plastic screws that mechanically are designed for plastic. The threads are widely spaced, tall and thin - They cut into the plastic with out breaking the mounting bosses (studs). The engagement with the plastic (screw thread in plastic boss hole) is ~ 100% leaving little or no air gap between the screw and the plastic. First set of Question - If using screws what would be the best type of screw to insure good contact to the stainless steel fibers? * High profile, thin thread, plastic screw like I described? * Self tapping type screw? What should the platting be? * Clear Zinc * Zinc Chromate? * Nickle on brass? * Stainless Steel? Is there any sort of liquid/paste like adative that could be added to the screw hole to enhance the electrical connection? We have experimented with metal inserts (PEM nut brand for example). What sort of bonding does one get when molded in? I suspect poor relative to press in. Can the inserts be plain brass or should they be plated like with nickle? Depth of inserts - Longer inserts should be better but I am concerned about cracking of the boss. Screen matterial in the screw boss. I have seen screen matterial embedded in conductive plastic. Perhaps it could help screws bond to the plastic as well. Any comments? Sounds messy. Coatings on top of conductive plastic? If a coating were placed on the inner surface of the conductive plastic it might make a good hybrid sollution but costly. Are there other considerations? If you respond today try CC to christopherdwe...@eaton.com So I get it at work too (the ITE guys can't handle this subscription list at work) This group is the best resource I have for this sort of topic - thanks in advance!! Chris Wells Senior Design Engineer Cutler-Hammer Pittsburgh, Pa. USA christopherdwe...@eaton.com
RE: Conductive Coating
Steel, nickel, and zinc are all relatively poor conductors, at least as compared to copper or aluminum. Of these, the best conductor is zinc. But in your application the type of metal to use as plating is clearly irrelevant, since the plating will carry very little current. Almost all of the current will flow in the metal substrate (steel or stainless steel), even taking skin depth into account (at any reasonable frequency you are liable to be shielding against). Low-300 series stainless steels (301, 302, 304, etc) are poor electrical conductors (and a really lousy thermal ones as well). The higher-300s series (316, 317, etc) are even worse. Their conductivity is many times worse than steel. But that may make little difference anyway in your application. As far as what finish is recommended on stainless, the answer is generally none. The passivated finish as supplied in the original sheet is all that is usually used. In any event, passivation or no passivation is entirely irrelevant to conductivity, since the passivation is simply a molecules-thick oxide layer that is too thin to have an effect on the electrical parameters. On that note, if you zinc plate, you MUST passivate after plating, or risk the typical white zinc corrosion products that result from exposure to humidity. Usually a chromate conversion coating is used for this purpose and this also makes an excellent paint base (to which the paint adheres very well). Painting nickel or chrome plate is not recommended since paint adheres poorly (especially to chrome plate), but there is no particular electrical reason why you would want to plate these metals anyway. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Sam Jayashankar [mailto:sam.jayashan...@sanmina-sci.com] Sent: May 29, 2002 10:27 AM To: EMC PSTC (E-mail) Subject: Conductive Coating Hi All, I have some queries regarding conductive coating for an enclosure design I am currently reviewing. The enclosure material is made of steel. The coating specified by the packaging/mechanical team is Zinc plate per ASTM B633, Type III, Class FE/ZN 5. How conductive is this Zinc plating? Does Nickel or Chromium plating offer better conductivity? The mechanical team is also looking into using stainless steel (passivate per SAE AMS QQ-P-35) for the enclosure doors. What is the recommended finish/coating for stainless steel? Thanks in advance for all help rendered. Regards, Sam Jayashankar EMC Engineer SANMINA-SCI 6751 - 9 Street N.E. Calgary, AB T2E 8R9 Phone: (403) 295-5124 Cell: (403) 875-1292 Fax: (403) 295-8862 E-mail: sam.jayashan...@sanmina-sci.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: English Translation of würfelförmiges
Warum kannst du nicht Deutsch verstehen?? (heh heh) It means cube shaped or cubic. The sentence means (as much as one can tell in such an abbreviated piece) about (or for, or with relation to) a cubic (or cube shaped) volume of 27 liters... Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: May 28, 2002 9:39 AM To: emc-p...@majordomo.ieee.org Subject: English Translation of würfelförmiges How does the German word würfelförmiges translate into English when used in the following phrase? . . . über ein würfelförmiges Volumen von 27 l . . . Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: digital devices
Yes, a switchmode power supply falls under FCC part 15. Also, if by timing signals you are referring to its switching frequency, I think you have lost a zero somewhere. No switchmode power supply operates in the audible frequency range around 9KHz or 10KHz (especially one used to operate a speaker); you probably meant it operates at 90KHz to 100KHz? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Kim Boll Jensen [mailto:kimb...@post7.tele.dk] Sent: May 27, 2002 1:12 AM To: EMC-PSTC Subject: digital devices Hi all I have an active loudspeaker which have been using a traditional power supply, but will now be using switch mode power supply. Until now it have not been under FCC part 15 and ICES 003, as fare as I understand. Is a switch mode power supply regarded as a digital device according to FCC part 15 and ICES 003. It uses timing signals of more that 9.000/10.000 cycles pr. second. Best regards, Kim Boll Jensen Bolls Raadgivning Denmark --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Coaxial Switches - use with spectrum analyzer and gear?
I'm curious about your comment regarding Kovar being used as relay contacts. The main (and only, as far as I know) claim to fame for Kovar (ignoring high temperature turbine blades etc.) is that it has a Tc that matches alumina and some glasses, so it is used as a backing for thin and thick film ceramic hybrids, and as leads for small diodes etc. that are fused into glass. There would seem to be no reason why relay contacts need to be made from a ferromagnetic material. After all they are simply passing current, so whether they are ferromagnetic or not would seem to be irrelevant (although Kovar's lousy conductivity certainly would matter!). Kovar's natural oxide layer would also seem to be a problem at low signal levels. Typically, relay contacts are made of silver (with various surface treatments), or in the case of very low current, gold plated silver (or gold alone). In reed relays, other contact materials may be used, but oxidation is impossible because reed relay contacts are sealed in glass, in either a vacuum, or an inert gas. So the whole thing is still a mystery. The minimum -20dB signal level that is claimed to be needed for the relay in question still sounds like a red herring. I have used various lower frequency RF 50 Ohm relays (at 500 MHz or so), and there was no problem with passing signals at -80dB or lower. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Christman, Timothy (STP) [mailto:timothy.christ...@guidant.com] Sent: May 24, 2002 1:53 PM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? This may not be the effect being referred to, but... Relays require a ferromagnetic alloy, such as Kovar for the contacts. The leads leading to the connector are more likely beryllium copper or some similar material. The weld or joint between them forms a thermoelectrically active junction, and an associated error potential. Ideally, the two contacts form two sets of junctions that are opposite in polarity. In reality, they are seldom identically constructed, and if there's a temperature gradient across the part the error is magnified. Perhaps this was an effort to stress that the signal amplitude should be in excess of the thermoelectric offsets. Another possibility -- Many small form-factor relays are the reed type, so wiping action across the contacts forms a conduction path. There may be a minute oxide layer there or elsewhere in the system which will create the non-linear behavior described. Point contact rectification and dielectric breakdown become possibilities. Probably not pertinent, but interesting. Timothy J. Christman Test Engineer Tel 651.582.3141 Fax 651.582.7599 timothy.christ...@guidant.com Guidant Corporation 4100 Hamline Ave. N. St. Paul, MN 55112 USA www.guidant.com -Original Message- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: Thursday, May 23, 2002 6:32 PM To: emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? As it is stated, below -20dB, nothing at all comes through the switch. Then once you reach that level, output signal level suddenly begins increasing from zero. That obviously makes no sense and is probably only a result of an engineering spec being lost in translation when Marketing created the Data Sheet. Losses are not an offset that must be overcome before any output is generated, but simply as Ken mentioned, a proportion of input power. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: May 23, 2002 1:37 PM To: emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? That information is from an application document found on the Dow Key web site. I can't say that I fully understand it myself. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Thursday, May 23, 2002 3:59 PM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: Re: Coaxial Switches - use with spectrum analyzer and gear? I don't understand the snipped statement below. Isn't the loss just a fraction of the power flowing through the switch? -- From: richwo...@tycoint.com To: emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? Date: Thu, May 23, 2002, 12:22 PM A minimum power of about -20dbm must be used to overcome the losses in the switch. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard
RE: Coaxial Switches - use with spectrum analyzer and gear?
As it is stated, below -20dB, nothing at all comes through the switch. Then once you reach that level, output signal level suddenly begins increasing from zero. That obviously makes no sense and is probably only a result of an engineering spec being lost in translation when Marketing created the Data Sheet. Losses are not an offset that must be overcome before any output is generated, but simply as Ken mentioned, a proportion of input power. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: May 23, 2002 1:37 PM To: emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? That information is from an application document found on the Dow Key web site. I can't say that I fully understand it myself. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: Thursday, May 23, 2002 3:59 PM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: Re: Coaxial Switches - use with spectrum analyzer and gear? I don't understand the snipped statement below. Isn't the loss just a fraction of the power flowing through the switch? -- From: richwo...@tycoint.com To: emc-p...@majordomo.ieee.org Subject: RE: Coaxial Switches - use with spectrum analyzer and gear? Date: Thu, May 23, 2002, 12:22 PM A minimum power of about -20dbm must be used to overcome the losses in the switch. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Emission Standards for Cell Phones and Antennas in Switzerland
Oddly enough, in Switzerland (and Germany, Austria etc.) they aren't called cellphones. They are called Handys. Part of a new language called DENGLISH (Deutsch + English). Useless fact-of-the-day. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: IEEE-EMC User Group [mailto:ieee-...@itl.co.il] Sent: May 21, 2002 3:45 AM To: Emc-Pstc Group (E-mail) Subject: Emission Standards for Cell Phones and Antennas in Switzerland Dear All, Does anyone know where I can find emission standards for cell phones and cellular transmitting and receiving antennas for Switzerland. I have been informed that the level acceptable in Switzerland is lower than the IRPA standard. Thanks to anyone who can help Best Regards David Shidlowsky Technical Writer EMC Laboratory ITL (Product Testing) Ltd. Kfar Bin Nun Israel Tel: +972-8-9797799 Fax: +972-8-9797702 Email: dav...@itl.co.il http://www.itl.co.il http://www.i-spec.com This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Some slightly disturbing interview news ...
Hmmm. the most politically correct engineer that has any brains Politically correct and having brains? Aren't the two mutually exclusive? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Jim Freeman [mailto:free...@chelsio.com] Sent: May 16, 2002 11:17 AM To: Berkley Cc: Ken Javor; Doug McKean; EMC-PSTC Discussion Group Subject: Re: Some slightly disturbing interview news ... Hi All, I have heard of this and know that it is performed as an information gathering tool. A company usually employs their own engineer designate(the most politically correct engineer that has any brains) and puts him on all the interview lists. This person writes reports as to what is being done outside and then the managers use this database to question their internal experts about why they are doing things a certain way,. Keep in mind that the managers have no idea how or what it takes to solve the problem but use the database to badger internal people and force them to investigate a problem in a way that doesn't match their skill set while at the same time expressing disappointment at how the job isn't getting done in a timely manner because of the insuficiency of expertise in the internal people. The internal person may even on the right track but will be forced off of it befause of management pressure. Another time I was actually queried about the values for particular constants and watched the politically correct engineer write down the answers in my presence. This was a case of a not particularly bright politically correct engineer. Thanks Jim Freeman Berkley wrote: This is nothing new.. I found this to be typical interviewing technique at several start-ups that I had interviewed with over the past 3-4 years. The questioning would get extremely detailed, and in my opinion, way too focused (for a first interview). I learned to recognize some tell-tale signs.. for instance, where my most of my responses to specific questions got an immediate reaction like but what if you already tried that and it didn't work? .. what else would you do... and the questioning would proceed way down, into the micro-level on this one problem. It was so blatant at one interview that, after a grueling 2 hours, I finally stood up and said hire me and you'll find out, then walked out. They called me back for a second interview! .. I kindly declined.. Be Good, George - Original Message - From: Ken Javor ken.ja...@emccompliance.com To: Doug McKean dmck...@corp.auspex.com; EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Sent: Thursday, May 16, 2002 12:54 AM Subject: Re: Some slightly disturbing interview news ... Happened to me personally, but not in Silly Valley. -- From: Doug McKean dmck...@corp.auspex.com To: EMC-PSTC Discussion Group emc-p...@majordomo.ieee.org Subject: Some slightly disturbing interview news ... Date: Wed, May 15, 2002, 6:45 PM Times are tough all round but there's no need to make things tougher. Here in Silly Valley, things are tough and I have made some attempts to find a few people jobs in my spare time. These are people I know personally. I'm sure I'm not alone in this venture. I'm sure most if not everyone on this list would also help. One headhunter who called me wanted to know if I was just plain nuts or just some sort of a good guy handing a job offer off to someone I knew who was looking. I told him it was none of his business smirk, just make sure to give so-and-so a call. Which they do. Unfortunately, what I have personally experienced in the past (rarely), and what appears to be happening at least with a few of companies currently is the following ... EMC job opening is posted. Resumes are sent. A few candidates are selected for interviews. Most of the interview centers on questions about how to solve some problems that are being experienced by said company. Then there's a decision not to hire anyone. Purchase req for new hires is closed. All candidates are rejected. A few months later, same company goes through the whole thing again. Only this time, there's a different set of questions to problems all being experienced by said company. Both sets of questions involving how-would-you-solve-this type of problems. I'm sure most of you know where I'm going with this. At the end of the day, the company or whoever in the company, has their solution or solutions. I'm not crying about this. My questions are ... Comes with the turf? Are you surprised to hear such a thing? Not surprised? Has is happened to you? Heard that it does happen but rarely and with some other company somewhere else? Happens all the time? Never happens? You gotta be kidden? So that's what that was all about! Thanks. Yea, but whaddaya gonna do about it? Well, if it does happen, so much the
RE: Constant for Change of Resistance formula.
Stating the proven principles of accurate thermal analysis is hardly muddling the knowledge pool. No one has suggested that increased resistance leads to increasing heat generation in an infinite spiral as you mention. This would obviously be nonsense, and is not predicted by theory or observed in practice. As I mentioned in an earlier post, increased resistance DOES lead to increased heat generation, which DOES in turn cause further resistance increase ...but this does not spiral on to infinity for the very reason that the system is nonlinear. Thermal issues ARE highly nonlinear. What DOES happen is that a new higher temperature plateau is reached where (as I wrote in my original post on this subject): The final temperature that the system stabilizes at, is reached when the logarithmically increasing (i.e. also very non-linear) heat transfer to the environment caused by increasing temperature, balances increased heat being generated. The bottom line is that heat transfer issues are unavoidably complex and require iterative solutions for accurate answers. That is why thermal analysis software is so hideously expensive, and requires such long times and high computer horsepower to converge on an accurate solution. While it may be possible to arrive at an approximate solution, for a limited set of parameters under a narrow subset of conditions by using rule-of-thumb simplification, it doesn't change the fact that an accurate solution is unavoidably far more complicated than you are presenting, and such a simplification must be understood to be just that: a simplification. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Sam Davis [mailto:sda...@ptitest.com] Sent: May 14, 2002 8:57 AM To: emc-p...@majordomo.ieee.org Subject: RE: Constant for Change of Resistance formula. OK, I've avoided jumping in on this exhausted thread, but here's my take on the situation. It's obvious that more than a few of the posters have not performed this test. When you cannot answer a question with more than a theory, don't throw it out there as fact. You muddle the knowledge pool. First off, why go to the trouble of performing the CoR measurements on a connector, when you can fairly accurately (and much more simply) use a thermocouple. If you decide you need the accuracy of the Change of Resistance measurement, the equipment used for this test is specialized and highly precise, (it's a milliohm meter, not your standard DMM). The meters I've used have been capable of measuring fractions of milliohms, down to microohms. And you do end up measuring the resistance of the leads. That's why you measure them separately, in the ambient, and subtract them from the system resistance in the formula to get the resistance of the EUT only. Also, there is specially designed equipment to perform this test while the EUT is energized, but the normal method is to run the EUT until thermal stabilization, disconnect power, and measure the resistance as it drops over time, and extrapolate back to time 0. The smaller the EUT, the faster you need to get the first measurement, and subsequent measurements because within seconds, the EUT could drop significantly, making your extrapolation inaccurate. And about the resistance to temp rise to resistance rise to temp rise - if it went on infinitum, all conductors (not just those under test) would eventually ignite. This only happens when you allow too much current. Sam Disclaimer - Sorry if I stepped on any toes, but I've got big feet. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at:
RE: Constant for Change of Resistance formula.
Chris, You may be correct that I was assuming a more complex situation than the original poster intended. It won't be the first time this has happened. However, I cannot entirely agree with your take on the situation. In your post you mention: I would assume that one of the conditions of using this formula is that the current flowing in the conductor at the time of resistance measurement must be low enough to cause negligible heating on its own. The original poster stated that he was trying to determine the change of temperature in a connector, caused by increased resistance of its conductors. This clearly implies that the increased temperature must be due to additional resistive heating of these contacts, which in turn means that there MUST be sufficient current flowing in the connection to cause non-negligible heating. After all, if the additional heating due to current flow through a more resistive contact material was, in fact, negligible, then the connector would not get hotter, and the OP would not be worrying about change of temperature based on change of resistance as he stated. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: May 13, 2002 2:09 PM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: RE: Constant for Change of Resistance formula. Bob, I read your initial response to this thread; and I think that your understanding of the situation is more complicated than it really is. I snipped the following from your response: Nonetheless, you cannot possibly directly determine what the temperature change of something as physically and geometrically complex as a connector, merely by factoring in what its resistance change is. Among other things, the solution is extremely non-linear and iterative. Changing resistance will generate more heat, which will increase temperature, which will generate even more heat and on and on! Add this to the fact the resistance coefficient with temperature is itself non-linear, and you can The situation that you describe ...changing resistance will generate more heat... is assuming that the heating in the conductor is due to current flow, possibly as well as ambient changes. In the situation that you describe, you have temperature changing (due to current flow), which increases resistance (due to temperature change)... which increases temperature (due to increased resistance) which increases resistance (due to increased temperature)... ... I assume everyone gets the point of that train of thought, so I'll spare any more cycles. You are also assuming a complicated mechanical situation, such as a connector; where there are interfaces, differing materials... many factors that would make the math messy. So, yes, I agree that your scenario could not possibly be described by a linear equation. However, I believe that the formulae that everyone is describing deal with the change in resistance due to temperature alone. I would assume that one of the conditions of using this formula is that the current flowing in the conductor at the time of resistance measurement must be low enough to cause negligible heating on its own. Even with that, the equation is probably an approximation for small temperature changes. Your point is well taken: that is...know the limitations of any formula that you apply. To twist an old proverb: Believe half of what you see, none of what your hear and about 10% of the formulae that can be reproduced by an ASCII email :-) Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Constant for Change of Resistance formula.
It appears that all these suggestions for finding temperature rise caused by increasing conductor resistance, are based on the fallacy that there is a direct relationship between the two. As indicated in an earlier post, this is an incorrect supposition. The solution to the problem is far too nonlinear to be realized by a simplistic calculation. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Bill Ellingford [mailto:bill.ellingf...@motion-media.com] Sent: May 13, 2002 5:18 AM To: 'Colgan, Chris'; emc-p...@majordomo.ieee.org Subject: RE: Constant for Change of Resistance formula. Hi Folks Further to the answer given, here is a little more data. The constant used is for the change of resistance with temperature. metals and alloys (conductors) all exhibit a different constant. This can be used for calculating temperature rise or resistance change. i.e. find the temp rise from a start and finish test measurement on a winding (for example) at the begining and end of a on load heat run or, find R for a given temp: using a table or the formula, resistance at various temperatures can be pre-determined from a measurement made at one particular temperature. A website with the formulae can be found at http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html Where you have a transition from one metal type to another, you must measure each metal part individually. If you have only two metals in contact, you may be able to apply a combination of the temp coefficient methods and transposition of the measurement of change of junction voltage formulae i.e. Thermocouple laws. Hope this adds some value: Bill Ellingford -Original Message- From: Colgan, Chris [mailto:chris.col...@tagmclaren.com] Sent: 13 May 2002 10:28 To: emc-p...@majordomo.ieee.org Subject: RE: Constant for Change of Resistance formula. Ned is referring to the constant used in the temperature rise calculated by change in resistance formula ie ... Where dt is the temperature rise, R1 is start resistance, R2 is end resistance, T1 is start ambient and T2 is end ambient. 234.5 is the formula constant for copper. This formula is used extensively when heat testing transformers and coils. I'm afraid I don't know the constant for brass but I believe the figure may be related to the inferred absolute zero of a material. Try asking a metallurgist? Regards Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:chris.col...@tagmclaren.com * http://www.tagmclaren.com -Original Message- From: Robert Wilson [SMTP:robert_wil...@tirsys.com] Sent: Friday, May 10, 2002 7:00 PM To: emc-p...@majordomo.ieee.org; Ned Devine Subject: RE: Constant for Change of Resistance formula. What are the units? 234.5 ...what?? Looking at what the units are, will basically tell you exactly what the property is related to. Nonetheless, you cannot possibly directly determine what the temperature change of something as physically and geometrically complex as a connector, merely by factoring in what its resistance change is. Among other things, the solution is extremely non-linear and iterative. Changing resistance will generate more heat, which will increase temperature, which will generate even more heat and on and on! Add this to the fact the resistance coefficient with temperature is itself non-linear, and you can see how this complicates things further. The final temperature that the system stabilizes at, is reached when the logarithmically increasing (i.e. also very non-linear) heat transfer to the environment caused by increasing temperature, balances increased heat being generated. To reach a solution, you need to iterate your calculations, where the results of one calculation are plugged as variables into the next iteration. Typically a thermal analysis program will require several hundred iteration before a converged solution results. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ned Devine [mailto:ndev...@entela.com] Sent: May 10, 2002 8:29 AM To: emc-p...@majordomo.ieee.org Subject: Constant for Change of Resistance formula. Hi, Does any one know how the constant for CoR formula was determined? I know the K is 234.5 for copper and 226 for aluminum, but what property is this related to? I am trying to determine the change in temperature of a connector, based on the change of resistance. The connector contacts are made of brass. Thanks Ned Ned Devine Program Manager Entela, Inc. 3033 Madison Ave. SE Grand Rapids, MI 49548 1 616 248 9671 Phone 1 616 574 9752 Fax ndev...@entela.com e-mail Entela, Inc. A Certified Woman Owned Business www.entela.com
RE: Constant for Change of Resistance formula.
What are the units? 234.5 ...what?? Looking at what the units are, will basically tell you exactly what the property is related to. Nonetheless, you cannot possibly directly determine what the temperature change of something as physically and geometrically complex as a connector, merely by factoring in what its resistance change is. Among other things, the solution is extremely non-linear and iterative. Changing resistance will generate more heat, which will increase temperature, which will generate even more heat and on and on! Add this to the fact the resistance coefficient with temperature is itself non-linear, and you can see how this complicates things further. The final temperature that the system stabilizes at, is reached when the logarithmically increasing (i.e. also very non-linear) heat transfer to the environment caused by increasing temperature, balances increased heat being generated. To reach a solution, you need to iterate your calculations, where the results of one calculation are plugged as variables into the next iteration. Typically a thermal analysis program will require several hundred iteration before a converged solution results. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ned Devine [mailto:ndev...@entela.com] Sent: May 10, 2002 8:29 AM To: emc-p...@majordomo.ieee.org Subject: Constant for Change of Resistance formula. Hi, Does any one know how the constant for CoR formula was determined? I know the K is 234.5 for copper and 226 for aluminum, but what property is this related to? I am trying to determine the change in temperature of a connector, based on the change of resistance. The connector contacts are made of brass. Thanks Ned Ned Devine Program Manager Entela, Inc. 3033 Madison Ave. SE Grand Rapids, MI 49548 1 616 248 9671 Phone 1 616 574 9752 Fax ndev...@entela.com e-mail Entela, Inc. A Certified Woman Owned Business www.entela.com
RE: A little off topic but ... exploding CD's ???
Going around corners presents another interesting problem, depending on the orientation of its axis. The vacuum chamber that such a flywheel must operate in (to make it practical) presents another interesting challenge. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Maxwell [mailto:chris.maxw...@nettest.com] Sent: May 10, 2002 5:47 AM To: Doug McKean; EMC-PSTC Discussion Group Subject: RE: A little off topic but ... exploding CD's ??? I hope that I don't lead the thread off on a tangent...but a similar problem is being encountered by those who envision magnetically levitated flywheel powered electric cars. (By the way, the flywheel is levitated, not the car) A well designed flywheel system can store electricity with a better weight to energy ratio of currently available batteries...But. In order to do so with a lightweight flywheel (about 50 pounds); the flywheel needs to spin up to something like 100,000 rpm. They are testing composite materials (graphite, kevlar...) and the testing has led to some spectacular failures with shredded flywheel all over the place. The other problem is...how do you contain these babies if the car has an accident. Just imagine a wreck that produces a bunch of 50lb buzz saws bouncing around the intersection...it wouldn't be pretty. As far as CD's...maybe everyone should just listen to George Jones... or something else that is slow enough to keep he speed safe :-) Chris Maxwell | Design Engineer - Optical Division email chris.maxw...@nettest.com | dir +1 315 266 5128 | fax +1 315 797 8024 NetTest | 6 Rhoads Drive, Utica, NY 13502 | USA web www.nettest.com | tel +1 315 797 4449 | --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: A little off topic but ... exploding CD's ???
No need to worry. First, a CD can be spun at many tens of thousands of RPM without destruction. But more importantly, the spin ratios are not straight multiples of the basic disk RPM. After all, if this were true, the 300 to 400 RPM maximum speed of a 1X CD player, would be 19,000 to 25,600 RPM, and 64X CD-ROMs do NOT rotate that fast. Much of the increase a 64X CD-ROM is claiming, is due to reading ahead and buffering, so that in normal intermittent use, the apparent transfer rate is (supposedly) 64X normal. This is why tests show that, when large amounts of data are being read, these drives cannot get anything close to their claimed data transfer rate. This is why one cannot read an entire audio CD into memory as a raw WAVE file, at anything close to the claimed rate. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Doug McKean [mailto:dmck...@corp.auspex.com] Sent: May 9, 2002 3:34 PM To: EMC-PSTC Discussion Group Subject: A little off topic but ... exploding CD's ??? As a matter of safety, has anyone really addressed the issue of the upper speed limit of CDs? Quoted from the following webpage ... http://www.qedata.se/e_js_n-cdrom.htm Introduction But where's the limit? Manufacturers try to outspin each other all the time by selling CD-ROM drives with higher and higher spin ratios. Spin ratios of 2x, 4x, 8x, 16x, 32x, 56x and 64x come in a never ending stream. The CD is forced to rotate faster and faster. At what speed will a CD blow up, and can you do something to prevent it from exploding? ... At the conclusion of the test, the author recommends the following ... Safety Recommendations The committee wishes, after finishing its work, to suggest the following safety precautions. Safe distance to a CD-ROM drive with spin ratio 64x CLV should be no less than 5 metres (15 ft.). All work with CD-ROM units should require safety goggles and protective clothing be worn. CD-ROM drives of the 64x CLV class and higher, should be provided with shrapnel protection of no less than 3 mm aluminium or 1 mm steel. To avoid operator inhalation of CD-ROM particles, CD-ROM drives should be provided with a dust suction fan with suitable filter, or have the fan duct connected directly to the outside air. In addition to the laser light warning label, CD drives should be affixed with another label warning against the hazard of shrapnel, such as the one below: With appropriate labels for exploding CDs. No. This isn't a joke. Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: stun guns on aircraft
Crime rates drop drastically in nations where guns are freely owned by the PUBLIC?? I suppose this explains why the US has a murder rate some 10 to 20 times that of western Europe, and whose extreme violent crime rates make it a pariah in the eyes of so many other nations? And where do you think the criminal approaching your wife with a gun managed to get a gun in the first place? Could it be because he lives in a country that believes owning a gun should be a citizen's right? Nah! Couldn't possibly be a connection! Reminds me of a cartoon I once saw, where Uncle Sam is pointing a gun at himself and has just managed to shoot another hole through his head. The caption is Damn! It did it again! I wonder what causes that? Ah, well, what else can one expect from yet another proud member of the NRA. Certainly not rational thinking when it comes to playing with toys that go bang. I'll get off my soap box now. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Sam Davis [mailto:sda...@ptitest.com] Sent: May 7, 2002 6:51 AM To: Gert Gremmen; Pettit, Ghery; 'Ted Rook'; Subject: RE: stun guns on aircraft This has nothing to do with EMC or Product safety, but with personal and public safety. I'm with Ghery. Gert, your misrepresentation of his statement is ludicrous. Statistics bear this out. Crime rates drop drastically in nations where guns are freely owned by the PUBLIC. Look at Australia. The gov't took the gun ownership rights away, and violent crime rose horribly. Guns are not only offensive weapons, but defensive weapons as well. If some criminal approaches your wife with a gun, would you prefer her to have a pistol, or a whistle? What do you want your cops to defend your streets with? What about your military, to guard your ability to go to work, make a living, support your family, without having to worry if you'll be a captive prisoner of war, or worse? What about the security force at your airport? Guns even the playing field. When you outlaw guns, only outlaws have guns. Law abiding citizens turn them in, and can no longer defend their homes with the NECESSARY force. Fortunately, I live in a locale where gun ownership is not only allowed, but almost expected. Statistically, there are more guns than people per household. There is also a very low rate of home invasion. Since concealed carry permits have been issued, all violent crimes have dropped. Hijackers take planes because law-abiding travelers are not packing heat. I own multiple guns, legally, and I pray I never have to fire them in self defense, but I pray I don't have to use my ADD policy either. BTW, Ted, your statement Unfortunately America was taken by force and is defended by force and is unlikely ever to change, I disagree with your first syllable. The reason we're the prime superpower is because the world knows we will use it if we have to. The reason our allies like us is because we've got their back, (and we've thrown billions of dollars to bail them out without actually expecting payback, but that's a completely different thread). Remember grade school, who got picked on? The kid that couldn't (or wouldn't) defend himself. The guys that were obviously able to return injury never had to fight. Think about that. If any of my statements offend you because of your national pride, I'm sorry. My national pride is what brought me in here. I mean no offense to your nation, just your government's anti-gun laws. My opinions are my own, but I know my boss will back me. He's a member, too. Proud member of the National Rifle Association, standing with my brothers, supporting our constitutional right to protect ourselves until the cops are able to arrive. Sam -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Gert Gremmen Sent: Tuesday, May 07, 2002 12:25 AM To: Pettit, Ghery; 'Ted Rook'; Subject: RE: stun guns on aircraft So Ghery, Please let us all know your future flight schedual, so we can avoid sharing the same plane ... As you might know, yesterday, in analogy to USA 1963 Kennedy, a Netherlands Prime Minister kandidate , Pim Fortuin, a fighter for the rights for free speaking, to the degree that he attacked laws against discrimination, was killed by a such representative of the TRUE FREE MEN . I supposed , Ghery , that your interpretation of being a FREE man is not limited to the WORD... Gert Gremmen -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Pettit, Ghery Sent: dinsdag 7 mei 2002 01:24 To: 'Ted Rook'; Subject: RE: stun guns on aircraft I've resisted jumping in in this fashion, but - FREE MEN OWN GUNS! Those who will trade essential freedoms for temporary security deserve neither - Benjamin Franklin. Folks, the 2nd Amendment pre-dates the wild west by a long time. Those of us who value our RIGHTS are tired of the wimps in
RE: What Every Startup Needs to Know About NEBS
MET Labs in California is fond of showing a video of this test. The equipment in the test was about a quarter of a rack tall. It took almost an hour before the flames really started in earnest, and a couple of hours before the flames finally subsided. In the process it was a real bonfire. Flames were 5 feet high at times. Personally, I am rather dubious about the relevance of this test. Why not just stick the equipment into a blast furnace and be done with it. I also felt the seismic test was rather unrealistic, since the resonances of the equipment and therefore peak amplitudes it is subjected to will dramatically change, depending on the actual seismic-approved rack it is installed in. Also, in real life there will be other equipment in the rack; not just a couple of dummy weights as in the test. One can expect the equipment to behave very differently in a real installation. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Dave Lorusso [mailto:dave.loru...@genband.com] Sent: May 7, 2002 7:30 AM To: Robert Wilson Cc: emc-p...@ieee.org Subject: RE: What Every Startup Needs to Know About NEBS I showed a film clip of failing the fire resistance test at the last Verizon NEBS Symposium (www.verizonnebs.com http://www.verizonnebs.com/ ), you're right, it was a big hit. Before I showed it, I asked the audience How many of you played with fire when you were a kid?. At least 2/3 of the audience raised their hands. Not too surprising from a group of compliance professionals who burn stuff for a living. The fire resistance test is definitely my all time favorite compliance test - the seismic test is a close second. Best regards, Dave -Original Message- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: Monday, May 06, 2002 7:38 PM To: emc-p...@ieee.org Subject: RE: What Every Startup Needs to Know About NEBS You never showed photos of the NEBS flame test! Nothing like burning your equipment to a crisp with a 1 foot high flame from a line burner, for good entertainment :) Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Dave Lorusso [mailto:dave.loru...@genband.com] Sent: May 6, 2002 3:11 PM To: 'emc-p...@ieee.org' Cc: 't...@world.std.com'; 'n...@world.std.com' Subject: What Every Startup Needs to Know About NEBS FYI, I just had an article published in Evaluation Engineering magazine titled: What Every Startup Needs to Know About NEBS. You can view it at: http://www.evaluationengineering.com/archive/articles/0502emc.htm The article details the steps we took at General Bandwidth to pass NEBS testing our first time out. There's a pretty good resource section at the end that's not in the print copy. I hope the group finds it useful. Best regards, Dave Lorusso Director of Product Integrity General Bandwidth, Inc. 12303 Technology Blvd. Austin, TX 78727 512-681-5480 (phone) 512-681-5481 (fax) dave.loru...@genband.com www.genband.com http://www.genband.com/
RE: stun guns on aircraft
Free men own guns. Yeah right. The true mark of a civilized country is that its citizens all own guns. Never been anywhere else, have you? It is just this sort if immature 19th century frontier mentality that is embarrassing the US in the eyes of the rest of the world. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Pettit, Ghery [mailto:ghery.pet...@intel.com] Sent: May 6, 2002 4:24 PM To: 'Ted Rook'; Subject: RE: stun guns on aircraft I've resisted jumping in in this fashion, but - FREE MEN OWN GUNS! Those who will trade essential freedoms for temporary security deserve neither - Benjamin Franklin. Folks, the 2nd Amendment pre-dates the wild west by a long time. Those of us who value our RIGHTS are tired of the wimps in the world trying to take them away. Ghery S. Pettit Life Member, National Rifle Association -Original Message- From: Ted Rook [mailto:t...@crestaudio.com] Sent: Monday, May 06, 2002 1:08 PM To: Subject: stun guns on aircraft and other safety considerations keep the hijackers off planes using ground security an airplane in flight is not the place to have gun fights too many lives are at risk the first priority is to get the plane safely on the ground, anywhere then at least the passengers have a chance Most citizens of most countries enjoy the security that comes from having thrashed out land rights, territorial disputes, and the systems of law and law enforcement before firearms were invented. America is one of the few places in the West that relies on firearms as a negotiating tool. This is poor judgement. Firearms are offensive weapons not negotiating tools. Giving someone a gun escalates an already dangerous situation. Now you want the pilot to not only assure the safety of the plane but also be an effective executioner. Asking too much IMHO. Unfortunately America was taken by force and is defended by force and is unlikely ever to change. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: What Every Startup Needs to Know About NEBS
You never showed photos of the NEBS flame test! Nothing like burning your equipment to a crisp with a 1 foot high flame from a line burner, for good entertainment :) Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Dave Lorusso [mailto:dave.loru...@genband.com] Sent: May 6, 2002 3:11 PM To: 'emc-p...@ieee.org' Cc: 't...@world.std.com'; 'n...@world.std.com' Subject: What Every Startup Needs to Know About NEBS FYI, I just had an article published in Evaluation Engineering magazine titled: What Every Startup Needs to Know About NEBS. You can view it at: http://www.evaluationengineering.com/archive/articles/0502emc.htm The article details the steps we took at General Bandwidth to pass NEBS testing our first time out. There's a pretty good resource section at the end that's not in the print copy. I hope the group finds it useful. Best regards, Dave Lorusso Director of Product Integrity General Bandwidth, Inc. 12303 Technology Blvd. Austin, TX 78727 512-681-5480 (phone) 512-681-5481 (fax) dave.loru...@genband.com www.genband.com http://www.genband.com/
RE: Stun Guns on Aircraft - summary and comments GK
Regarding the perforation of the aircraft by bullets, and the supposed gradual depressurization that should occur, it might be worth remembering the disaster of the world's first fleet of jet passenger aircraft, the British Comet. In the early 1950s they were falling out of the sky in some numbers. Very inconvenient. This was some 5 years before Boeing came out with its 707. Stress cracking caused a single, small window (about the same size as normal side windows) that the plane had on the top of the cabin, to begin to weaken. At some point the window began to crack and then suddenly gave way. The result was that nearly the entire contents of the cabin were explosively sucked through the open window. It took years to understand what had happened since all they could find was plane wreckage (usually under water) with bodies and seats scattered over an improbably large area. The result is that until the problem was found some years later, and corrected, the aircraft was taken out of service. It was this that allowed Boeing with its 707 (and shortly later, Douglas with its DC8) to catch up and dominate the market at the time. Suggesting that the only problem with bullet holes is that the pressurization system couldn't keep up with the air leakage, is therefore rather simplistic. The real problem is what happens when a window is hit and the pressure differential takes over causing explosive decompression. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Gregg Kervill [mailto:gkerv...@pgtv.net] Sent: May 6, 2002 9:42 AM To: emc-p...@majordomo.ieee.org Subject: RE: Stun Guns on Aircraft - summary and comments GK Dear All, Many thanks for your comments - I think it may be worth making some comments in summary: 1- Lightning has the same effect. Disagree - lightening is an external effect - Physics 101 and the Ice Pail experiment. If anyone doubts the difference go and visit the Munich Science Museum where every day (I think they still do it) a volunteer climbs into a metal 'pod' and is winched between two electrodes (about 20 feet apart) and becomes part of the discharge path. Seeing it sure beat reading about it at school. Any discharge on the inside of the Ice Pail is transferred 'instantaneously to the outside surface - this is, after all, the principle upon which the Van de Graff(sp?P generator is based. (Note the volunteer does NOT wave out of the window!!!) 2- Holes in structure versus hole and carriers in semiconductor substrates (yes it was a pun). I agree with those who preferred the idea of perforated eardrums (depressurization) to perforated electronics. 3- Dead Pilot versus Dead Electronics. Neither is ideal - but many (most) commercial aircraft are fly be wire - One of my clients make Simulators - and I flew (for the first time ever) and Air Bus (simulator) from London Heathrow to London Gatwick - Landed (ON THE RUNWAY) and taxied (the most difficult part) to the airport. I had full control of the simulator and was flying by instruments. The controls are ALL electronic and if there had been multiple (i.e. non-random) fails then even a pilot would not have been able to move the control surfaces. 4- Testing - at 50kV? any comments from ESD engineers out there? 5- TASER versus Stun gun - thanks for correcting my misunderstanding - Two comments - First - if the stun gun is discharged through the airframe there will be an induced potential in local electronic systems. Second - if I must turn off my tape recorder (powered but a single AA cell) because it may affect systems then how is discharging 50k considered to be safe and OK??? 6- Design of interfaces to cope - some of the prototype systems that I did safety and reliability work on in (1995)uses surface mount components to provide lightening protection - these devices would not provide Creepage distances of more than a couple of millimeters. 7- Ground computers - I agree that this is worrying - the UK has even more out of date equipment and then the new system (that will control air traffic in the South of England) used equipment (and software) purchased in the late 80's early 90's. I just hope that it still works when they take it out of the box. The point is that RANDOM failures exist and there procedures have been developed (and practiced) to deal with them. Anything that induces non-random and multiple failures is - I suggest - another ball game. 8- The chances are low - I agree - I was flying back from the west coast the morning of 9-11 and I did not get a warm fuzzy feeling about probability when I watched the news footage - but I have made many flights since and it will not stop me from flying. I am grateful for the fact that Europe and the middle East are sharing their security experiences with the US. Security is a cultural thing and the US has a long way to go before it provides the same level of security from officials AND MORE IMPORTANTLY from
RE: Stun Guns on Aircraft.
...at least not North American trains, whose technology and infrastructure has fallen embarrassingly far behind that of much of the rest of the world. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: lisa_cef...@mksinst.com [mailto:lisa_cef...@mksinst.com] Sent: May 3, 2002 1:38 PM To: Fred Townsend Cc: emc-p...@majordomo.ieee.org; Gregg Kervill; owner-emc-p...@majordomo.ieee.org Subject: Re: Stun Guns on Aircraft. Well, I'd debate comparing lightning to a stun gun... one is on the outside, and one on the inside. Lightning has a bit more of a barrier to overcome than say 3,000 Volts to an instrument panel. I'm with Gregg... Hadn't really thought of it, but now that I have, give them the guns! Gregg, it's bad enough being in Reliability getting on a plane without thinking of the probability of failure, how old the parts are, is there enough redundancy, number of failure free trips etc. etc. etc. I think you've just put the last nail in the coffin ; - ) .and trains aren't building too much confidence these days either . Lisa --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Stun Guns on Aircraft.
I wouldn't get too paranoid about it. You are probably far more at risk on the ground in any US city, where a substantial number of people on the street are packing heat. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Gregg Kervill [mailto:gkerv...@pgtv.net] Sent: May 3, 2002 9:38 AM To: emc-p...@majordomo.ieee.org Subject: Stun Guns on Aircraft. There have been several reports here (in the US) that airlines are placing guns or stun-guns on aircraft. I understand the risk of a bullet - I understand that the risk can be reduced by using a flat, disc-shaped, rubber projectile. BUT, the though of ANYONE discharging a stun gun on a flight deck full of mission critical (and sometimes not well buffered) electronics scares me more that the though of a terrorist. Please can someone tell me that I should not worry - or to stop flying. Best regards Gregg --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Power Factor regulations.
I have a general question regarding power factor limits relating to the design of off-line switchmode power supplies. We will be starting the design of a relatively simple, off-line switchmode power supply that will be used to power an LED Luminaire (for lighting up the outside of buildings). A power supply will be used to drive each of the 3 colours independently (for dynamic colour changing). It will be designed for universal 120/230 Volt input, with an adjustable 20 to 28 Volt DC output. Power output will be 40 Watts maximum. As mentioned, 3 of these power supplies will be used in each Luminaire. My question is: what (if any) power factor requirements are we required to meet, both for North America and for the EU. My first thought was that there are no specific power factor requirements since ordinary computer power supplies have no PFC correction whatsoever (at least not the ones normally available here in North America). But I recall a year or two ago, a conversation with Jim Eichner (one of the inhabitants of this group) where he mentioned there were impending EU power factor requirements. Can anyone shed any light on what PF requirements exist at this power level? Bob Wilson TIR Systems Ltd. Vancouver. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: General Product Safety Directive - sorry missed something
With regards to the need to subject something running from a 9V battery to a battery (pun not intended) of safety approvals, to me this shows how some aspects of regulatory control are just a solution searching desperately for a problem. There are times when it seems to me that the entire process, which had sensible beginnings, has come completely off the rails. I can't wait for the day when toothpicks need to carry a litany of approvals. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Gregg Kervill [mailto:gkerv...@pgtv.net] Sent: April 29, 2002 7:29 AM To: richwo...@tycoint.com; emc-p...@majordomo.ieee.org Subject: RE: General Product Safety Directive - sorry missed something -Let's take an example of a non-rechargable 9V battery operated -ITE product(sic) Consider the liability and your defense - it you review to the ITE standard then you have performed due diligence - if you do not review to the ITE standard then you have not! If you assume that the product is safe and there is an accident what is you defense??? There may be an issue about CEMARKING the product:- LVD/MDD/EMC/RTTE etc - REVIEW and CE MARKING GSD - REVIEW IMPORTANT PRINCIPLE:- The GSD is merely a catch-all to make sure that unsafe products are not put on the market. It covers any product that is not covered by a harmonized standard - so there is no option. Whether the ITE - LVD - GSD apply is irrelevant to safety and reviews. However it would be covered by the RTTE and that would require a file and CE Marking. Best regards Gregg PLEASE NOTE: We are currently experiencing serious problems with our service provider PLEASE reply only to gr...@test4safety.com mailto:gr...@test4safety.com and ignore any reference to pgtv.net, Thank you. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: A very nice game
One more thing I forgot to mention, that may be useful. Pegasus (the email program I use at home) has a very nice Selective Download feature, that allows you to review what is on your server BEFORE downloading it. Thus, you can screen and delete (at the source!!) all suspicious messages or advertisements, without ever downloading them. When I had a problem with some idiot who felt compelled to email me 300 to 500K file attachments some time ago, as well as a group of people whose Outlook was emailing me virus attachments on a daily basis, this feature was really quite handy. Pegasus is available free at www.pmail.com Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Wilson Sent: April 24, 2002 11:37 AM To: emc-p...@ieee.org Subject: RE: A very nice game All of which makes one wonder why one would ever use IE as a mail reader! Rather like using a wrench as a hammer; sure, it can be made to work ...but why? Personally, I use Outlook at work (only because I have to). But at home, I use Pegasus which I feel is the best email program going, and it is free for the download. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Douglas C. Smith [mailto:d...@emcesd.com] Sent: April 24, 2002 10:36 AM To: Robert Wilson Cc: emc-p...@ieee.org Subject: Re: A very nice game Robert, You do not have to open the attachment on this one at all if you have IE! Just preview or open the message. During virus outbreaks, like this one, I use a great webmail reader mail2web.com to preview my mail before downloading it. Doug Robert Wilson wrote: In spite of the attachment having been removed by the system, it was pretty darned obvious what this must have been. It always amazes me that people are foolish (stupid?) enough to open attachments to obviously suspicious emails like this one, that are from people they don't know, and subjects that make no sense. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Bill Ellingford [mailto:bill.ellingf...@motion-media.com] Sent: April 24, 2002 4:37 AM To: 'jmw'; emc-p...@ieee.org Subject: RE: A very nice game Importance: High URGENT Please be aware that the above E-mail to the EMC group contained a virus. Fortunately our system removed it from the message. Bill Ellingford -Original Message- From: jmw [mailto:j...@jmwa.demon.co.uk] Sent: 24 April 2002 22:59 To: emc-p...@ieee.org Subject: A very nice game -- Virus Warning Message (on gemini2) setup.exe is removed from here because it contains a virus. - * --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list -- --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line
RE: A very nice game
For what it's worth, an absolutely excellent virus purge program is F-Prot, available from Frisk Software International at: http://www.f-prot.com/f-prot/download/ The DOS version is FREE and supported with very frequent (almost weekly) virus signature file updates. It runs just fine in a DOS window on WindowsNT, 2000, XP, 95 and 98. I have used it several times to eliminate viruses my son managed to get, and once to locate and purge a neighbor's computer of a virus that McAfee was unable to disinfect. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Douglas C. Smith [mailto:d...@emcesd.com] Sent: April 24, 2002 10:33 AM To: Chris Chileshe Cc: 'Bill Ellingford'; emc-p...@ieee.org Subject: Re: A very nice game Hi Chris and the Gang, It was probably a particularly nasty one called W32/Klez.h@MM which I have received through other channels several times lately. It is bad enough that if you actually get infected (McAfee will prevent this if your DAT files are reasonably new) you have to go into DOS and follow steps outlined my McAfee to get rid of it as it disables virus scanners. It appears to exploit an incorrect MIME header which causes IE to do some nasty things to your computer automatically by just opening or previewing the message. MAC's and PC's with Netscape Mail do not seem to be infected. I opened the letter in Netscape Messenger and did not get either a warning message or an infection. A URL on McAfee about this is: http://vil.mcafee.com/dispVirus.asp?virus_k=99455 One way to help avoid this type of thing is not to open email larger than a few tens (a long text message) of kB without knowing before who sent it and why. Long messages can harbor viruses. Doug Chris Chileshe wrote: Bill, Do we know which virus it was? Regards -Original Message- From: Bill Ellingford [SMTP:bill.ellingf...@motion-media.com] Sent: Wednesday, April 24, 2002 12:37 PM To: 'jmw'; emc-p...@ieee.org Subject:RE: A very nice game Importance: High URGENT Please be aware that the above E-mail to the EMC group contained a virus. Fortunately our system removed it from the message. Bill Ellingford -Original Message- From: jmw [mailto:j...@jmwa.demon.co.uk] Sent: 24 April 2002 22:59 To: emc-p...@ieee.org Subject: A very nice game -- Virus Warning Message (on gemini2) setup.exe is removed from here because it contains a virus. - * --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk This e-mail has been scanned for all viruses by Star Internet. The service is powered by MessageLabs. For more information on a proactive anti-virus service working around the clock, around the globe, visit: http://www.star.net.uk --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list -- --- ___ _ Doug Smith \ / ) P.O.
RE: A very nice game
All of which makes one wonder why one would ever use IE as a mail reader! Rather like using a wrench as a hammer; sure, it can be made to work ...but why? Personally, I use Outlook at work (only because I have to). But at home, I use Pegasus which I feel is the best email program going, and it is free for the download. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Douglas C. Smith [mailto:d...@emcesd.com] Sent: April 24, 2002 10:36 AM To: Robert Wilson Cc: emc-p...@ieee.org Subject: Re: A very nice game Robert, You do not have to open the attachment on this one at all if you have IE! Just preview or open the message. During virus outbreaks, like this one, I use a great webmail reader mail2web.com to preview my mail before downloading it. Doug Robert Wilson wrote: In spite of the attachment having been removed by the system, it was pretty darned obvious what this must have been. It always amazes me that people are foolish (stupid?) enough to open attachments to obviously suspicious emails like this one, that are from people they don't know, and subjects that make no sense. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Bill Ellingford [mailto:bill.ellingf...@motion-media.com] Sent: April 24, 2002 4:37 AM To: 'jmw'; emc-p...@ieee.org Subject: RE: A very nice game Importance: High URGENT Please be aware that the above E-mail to the EMC group contained a virus. Fortunately our system removed it from the message. Bill Ellingford -Original Message- From: jmw [mailto:j...@jmwa.demon.co.uk] Sent: 24 April 2002 22:59 To: emc-p...@ieee.org Subject: A very nice game -- Virus Warning Message (on gemini2) setup.exe is removed from here because it contains a virus. - * --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list -- --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: CE for Fluorescent Lamps
Just as a matter of curiosity, regarding the trailing boilerplate on your message, what could possibly be accomplished by forwarding an incorrectly delivered email back to the sender? The recipient will still have the original message. Sounds like someone isn't too clear on the concepts of email! Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: April 24, 2002 6:10 AM To: EMC-PSTC (E-mail) Subject: CE for Fluorescent Lamps Dear All, Some fluorescent lamps (the bulb) are marked with CE and others are not. What European Directives and standards should fluorescent lamps have to comply with? This e-mail message may contain privileged or confidential information. If you are not the intended recipient, you may not disclose, use, disseminate, distribute, copy or rely upon this message or attachment in any way. If you received this e-mail message in error, please return by forwarding the message and its attachments to the sender. PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: + 972-(0)3-5339022 Fax: + 972-(0)3-5339019 Mobile: + 972-(0)54-838175 http://www.itl.co.il http://www.i-spec.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: A very nice game
In spite of the attachment having been removed by the system, it was pretty darned obvious what this must have been. It always amazes me that people are foolish (stupid?) enough to open attachments to obviously suspicious emails like this one, that are from people they don't know, and subjects that make no sense. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Bill Ellingford [mailto:bill.ellingf...@motion-media.com] Sent: April 24, 2002 4:37 AM To: 'jmw'; emc-p...@ieee.org Subject: RE: A very nice game Importance: High URGENT Please be aware that the above E-mail to the EMC group contained a virus. Fortunately our system removed it from the message. Bill Ellingford -Original Message- From: jmw [mailto:j...@jmwa.demon.co.uk] Sent: 24 April 2002 22:59 To: emc-p...@ieee.org Subject: A very nice game -- Virus Warning Message (on gemini2) setup.exe is removed from here because it contains a virus. - * --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: High Temp Caps and Inductors
Just to keep the record straight, Kapton is a polyimide, not a polyamide. They are vastly different. Polyamide is the general name for the family of polymers commonly referred to as Nylon. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Scott Lacey [mailto:sco...@world.std.com] Sent: April 21, 2002 6:22 AM To: lfresea...@aol.com Cc: emc-p...@majordomo.ieee.org Subject: RE: High Temp Caps and Inductors Derek, You might try Texas Components (www.texascomponents.com) for high temperature capacitors. They claim usage up to 200 C. I suspect you will have to build (or have built) the inductors. You might check with Dupont to see if Kapton (a high-temperature polyamide) would be suitable for cores. You will also need to obtain magnet wire with suitable insulation, and I suspect that you will have to either weld or silver solder the interconnections. Once you have determined the materials choices any good custom magnetics house should be able to produce the inductors in quantity if needed. Good Luck, Scott Lacey -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of lfresea...@aol.com Sent: Friday, April 19, 2002 5:19 PM To: emc-p...@majordomo.ieee.org Subject: High Temp Caps and Inductors Hi all, I'm designing a filter that has to live and work with an Ambient temp of 180 C. Does anyone have suggestions as to component vendors that I could contact for parts? Thanks, Derek Walton. L F Research
RE: High Temp Caps and Inductors
A lot depends on the frequency you are operating at. A low frequency filter may use electrolytic caps, for example, and there is no way you will ever get 180°C electrolytics! Most of the common non-electrolytic capacitor dielectrics won't have a hope of operating at this temperature either. Maybe if you clarify the type and frequency of the filter... You are also at or above the melting point of normal tin-lead solder, so that is going to make things just a tad difficult. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: lfresea...@aol.com [mailto:lfresea...@aol.com] Sent: April 19, 2002 2:19 PM To: emc-p...@majordomo.ieee.org Subject: High Temp Caps and Inductors Hi all, I'm designing a filter that has to live and work with an Ambient temp of 180 C. Does anyone have suggestions as to component vendors that I could contact for parts? Thanks, Derek Walton. L F Research
RE: Decoupling - capacitor values
Not sure this would be a cure in this instance. This is effectively the same as adding a lossy inductor in series with the cap, which would tend to negate any benefits of using a cap with lower self inductance. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: April 18, 2002 4:57 AM To: emc-p...@majordomo.ieee.org Subject: RE: Decoupling - capacitor values Consider adding a ferrite bead in the 5V trace to the microprocessor. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: Wednesday, April 17, 2002 4:50 PM To: emc-p...@majordomo.ieee.org Subject: Decoupling - capacitor values A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Decoupling - capacitor values
Capacitors can continue to function quite well above their self resonance. You should not be worrying about choosing a cap based on self resonance per se. However, it is standard practice to parallel a 0,1 uF bulk bypass cap with a much smaller NP0 or C0G type (say 470 pF or 1 nF), especially in RF work. (I'm not sure why you chose the rather odd value of 820 pF) The reason has little to do with self resonance directly. The main reason is that the ESR of the larger cap begins to rise to unacceptable levels as frequency rises (chiefly due to its self inductance). The low-value NP0 cap has much lower self inductance, hence it continues to function as a true capacitor at higher frequencies. As for as specifically using an SMT cap is concerned, you can do this if you want, but it isn't a requirement. The frequency you are concerned with (the low hundreds of MHz) is still pretty low frequency. Normal leaded devices will work just fine provided you ensure the board layout is done properly (which you need to do anyway), that the cap is inserted straight into the PCB, and that the leads are not formed so it stands above the PCB. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: am...@westin-emission.no [mailto:am...@westin-emission.no] Sent: April 17, 2002 1:50 PM To: emc-p...@majordomo.ieee.org Subject: Decoupling - capacitor values A microprocessor is driven by a 12MHz clock. The 5V Vcc-pin is decoupled by a 100nF capacitor with a few mm leads. We can observe an unwanted 156MHz signal on the 5V line, maybe 13th harmonic of 12MHz. We will try to suppress/decouple this 156MHz signal. Suggestion: Insert a SMD ceramic capacitor of value 820pF in parallel with the existing 100nF. The reason for the low value 820pF is because the capacitor self-resonance frequency is approximate 180MHz, and I believe it is important to choose a Cap value with a resonance frequency higher than the frequency we would like to decouple. Does it make sense? Best regards Amund Westin, Oslo/Norway --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: EMC SIX LAYER PCB
If this is what you feel in necessary at moderate frequencies (I believe the original discussion was related to 600 MHz), I'd hate to see what you might feel is required at high frequency. :) The idea of chip in board that you mention is not new. It was first tried in the Far East some years ago as a means of allowing closer component packing. So far, it has been shown to be impractical. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Wan Juang Foo [mailto:f...@np.edu.sg] Sent: April 3, 2002 5:54 PM To: Cortland Richmond; ieee pstc list Subject: Re: EMC SIX LAYER PCB Assuming we are referring to small SMD components. The voltage drop across a capacitor, (in this instance I take it that you meant the bypass capacitor) is a function of the gap between the vias from the power and ground planes. Here is another little trick, but it is subjected to having the manufacturing and assembly people cooperating on this issue of board performance. I must caution that this stage of development in general, manufacturing do not allow placing a pair of closely spaced via (pwr gnd) right under a cap. In ASCII art the plan view of the pad and via combo looks like this. []:[] This however would push the typical resonance by a few octave over the conventional layout and it is dependent on the thickness of the board. The next step in the development is to boast the ability of the buried capacitance by inserting a 0603(1.6x0.8x0.8 mm) sized capacitor vertically into a hole on the PCB and solder the top and bottom ends. This have been found to fit well in the standard 1.6 mm thick board. The hole can have partial plate through. Again in ASCII art the elevation view looks something like this. ] C [ A = pwr and ground layer ] P [ I can not wait to drive all the PCB shopfloor and assembly people up the wall every time I come up with an innovation. cheers Tim Foo Cortland Richmond 72146.373@compuserve. To: John Coyle jco...@silent-witness.com, ieee pstc list emc-p...@ieee.org com cc: (bcc: Wan Juang Foo/ece/staff/npnet) Sent by: Subject: Re: EMC SIX LAYER PCB owner-emc-pstc@majordo mo.ieee.org 04/04/02 01:35 AM Please respond to Cortland Richmond A good thread. Some additional thoughts. This is a favorite question of interviewers hiring EMC engineers (any reading?): How would you stack this board? Looking at the problem as controlling impedance, things fall into place. Impedance to signal returns is impedance to signals. One SHOULD avoid switching reference planes. But the effect of switching reference planes is reduced if the potential required to pass return current between them - impedance, including between sides of the SAME plane - is minimized, which is where nearby ground via's and bypass capacitors come in. Current flowing through a via or a capacitor creates a voltage drop which drives the planes it connects, as a radiator. A good antenna may be made out of planes connected by a via, with RF applied between them. We need to avoid doing this by _accident_! The return path for a trace penetrating a reference layer should be as close as possible to the penetrating signal. While having it further off does not change the via's impedance, it does require current flowing through it to go further and increases the size of the radiating and coupling loop. This is also an impedance inserted in series with the desired signal. A bypass capacitor is is not only a path for return currents, but a place where cross talk can occur; it is a common impedance for all currents which flow through it, and voltage across it is in series with signals whose currents pass through it. If it is used to pass signal return currents, it needs to be sized not only for the current demand of devices its storage supplies, but also for the edge rate of signals whose return currents pass through it. If it is operated above self-resonance, it _may_ form a parallel resonant circuit with parasitic capacitance (or other capacitors), and add unexpected impedance to the signal return. At the right (wrong) place this can do a good impersonation of the feed to a patch antenna. It is common now to use a pair of planes, power and ground, sometimes on a very thin layer (AKA buried capacitance) to minimize power supply impedance. Unless this pair is rather extensive, it will need to be augmented by discrete bypass capacitors, which should not have long via's connecting them. This means near the surface. Signal traces need to be near planes for high-frequency return currents. BGA technology requires micro-via's between devices
RE: Danger and Power of Lightning
Clearly, we need to ensure that lighting carries the appropriate regulatory warnings! A couple of paragraphs of the usual rambling UL/CSA warnings and cautions should do the trick. :) Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: geor...@lexmark.com [mailto:geor...@lexmark.com] Sent: April 2, 2002 10:35 AM To: emc-p...@ieee.org Subject: Danger and Power of Lightning A year or so ago, I met a retired IBMer and his wife whose teen-age son was stuck and killed some years ago by lightning in the outfield of a baseball game that had just begun. Other than some distant clouds, there was no warning that this might happen, no rain or thunder. Now, I have just learned of the severe lightning damage done to the home of a guy I managed in the '80s. I have pasted his account below, with comments in brackets [ ] of additional damage findings. It is evidence of the sheer power in a lightning bolt, and the strange paths it chooses to follow in attempting to establish the best path between the sky and good earth ground. = Friday [March 29] around 3:15pm my house was hit by lightning. Right now we're in a motel up the road because we don't have any electricity (light, heat or phones). The utility company pulled the meter to inspect and won't reinstall until house wiring is inspected. Due to the Easter weekend we couldn't get anyone out before Monday. The bolt hit in yard blowing two bushes completely out of ground then jumped into the rear wheel of my Corvette melting spots on both rear mag wheels as it went through and melting the car cover near wheels. It blew several huge holes in cement driveway and then hit my garage where it blew out outlets and switches, blew drywall and insulation completely across garage, blew out garage window, structurally damaged garage door brick pillar that supports it and tore gutters and a section of garage roof at corner off house. The new heat pump is fried along with phone lines, cable lines. There's also a hole in living room ceiling and several other holes in roof. Pieces of my driveway rained down on the house, two large chunks came through roof and living room ceiling while the other chunk came down above our bedroom, hit a rafter and stayed in attic. My garage was full of smoke but no fires, just insulation and wood that was seared. The Fire dept. used an infrared camera to make sure nothing was continuing to burn in wall and they covered holes in roof. We've found large chunks of driveway completely imbedded in neighbors yard 150' from hole in driveway. My neighbor was out working in his backyard about 250' away and said the bolt hit just when he dug into ground with a shovel, sparks flew from shovel and he has bruises on his arms from jolt and was hit by small pieces of flying cement from my driveway. At first he wondered what he had hit with his shovel. Several people on street lost computers, phone lines and cable. The technician said it took out a whole section of county , 1000 customers and my house was ground zero. [Later evidence seems to indicate a complicated path for the lightning to reach a good earth ground, probably the buried water or sewer pipes in the street. It seems to have hit metal gutter above garage, traveled several feet before jumping to house vertical wiring near the garage door, downward to the metal angle iron along bottom of door, then lept to steel re-bar in the concrete driveway, to the end ot the re-bar and then to a wheel on the car parked there, thru the car body and back to more re-bar in the concrete, then under the shrubs, possibly heading for the buried street utlities. Two craters in the driveway indicate where it entered and exited the encased re-bar.] --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald:
RE: Faying
Yeah, blame John! :) For what it's worth, in the 25 years I have been involved in the mechanical packaging design of electronic enclosures, I have never heard of the word faying. One can't help but wonder if someone just misspelled facing. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Price, Ed [mailto:ed.pr...@cubic.com] Sent: April 1, 2002 6:47 AM To: 'EMC-PSTC List' Subject: Faying A couple of weeks ago, there was a thread discussing bonding techniques for ground studs. I suggested that MIL-B-5087 had some nice drawings showing typical accepted military practices. Of course, MIL-B-5087 has been superseded by MIL-STD-464, but you can still find electronic copies of MIL-B-5087. Jacob Shanker read through all of the 464 sections on Bonding, and then asked me if I knew what the term faying meant. It seems that MIL-STD-464 uses that term without any definition, as if it's a very common American English word. IMHO, I consider myself to possess a rather decent vocabulary. But faying left me puzzled, even after closely reading the context of the several citings in MIL-STD-464. It's certainly not in any common usage in my part of the world. I certainly wouldn't want to call something faying at any typical US military base. So, off to the dictionary web sites. 1. Britannica says: not found. 2. Merriam Webster says: Main Entry: fay // Pronunciation: 'fA // Function: verb Etymology: Middle English feien, from Old English fEgan; akin to Old High German fuogen to fit, Latin pangere to fasten Date: before 12th century : to fit or join closely or tightly 3. Harcourt's Metallurgy Engineering Dictionary says: faying surface // Metallurgy: the interface between two metallic parts that are to be joined. 4. Finally, turning to Google in desperation for a simple explanation, I find pictures at: http://www.offroaders.com/info/tech-corner/reading/bolt-tension/bolt_ten sion .htm So after all this searching, I find that MIL-STD-464 faying is just a 12th Century Old English way to say facing or mating surfaces. I'm not sure how he did it, but I suspect John Woodgate is to blame for this. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: chassis bonding - star washers enough?
Some answers to your questions: - Star washers (internal, not external) will cut through any normal paints, including powder paints. I have never seen a situation where fully tightening a screw would fail to make a good connection if an internal tooth lock washer was used. But having said that, there are those who would say that this cannot be definitely proven, and so paint masking under the screw will be necessary, if only to make people (i.e. UL etc.) feel more comfortable. - Standard internal tooth lock washers are as good as it gets. - Star washers do make a gas-tight seal when the screw is tightened properly. Light oxidation becomes irrelevant, as does re-oxidation at the contact points. - Because of the aforementioned gas-tight connection, special surface treatments are not beneficial. - PEM nuts ARE self clinching. Because they cause metal to flow under very high pressure, they make a gas-tight connection to the metal they are inserted into. Any type of PEM (or similar other brand) nut is as good as any other in this regard. The differences are in the nut part, not the way that metal is displaced when inserting. - The common type of captive lock washer screw is called a SEMS type, and is simply a normal screw with a normal internal tooth lock washer held captive by an undercut below the head. They function identically to screws with separate internal tooth lock washers. - If a lock washer is used, there is no point in using an anerobic screw locker like Loctite. Nonetheless, because of the gas-tight nature of the lockwasher interface, the use of Loctite will not affect the electrical connection between washer and screw or part. The pressure at the points of the lockwasher amounts to many tens of thousands of psi. Any liquid (i.e. loctite) will be squeezed aside. As for preferred types. Anerobic thread lockers are all essentially the same (chemically), being based on a methacrylate ester formulation. Some are more viscous, others less so; some are more reactive (harden faster) others less so, but this matters little when they are subject to the extreme pressure at the points of the lockwasher. - Use of a passivation coating like chromate conversion coating on zinc-plated steel (yellow, clear, or whatever), or Alodine on aluminum (also simply a type of chromate conversion coating) is a very good way to assure a stable interface under medium contact pressure. But its basic purpose is to ensure a consistent surface before connection is made. Since it is a sort of gel, literally mere MOLECULES thick, it is not going to affect a high pressure electrical connection in any way. It is common to hear people say that chromate coatings are conductive. This is completely false. Chromates are insulators. It is just that they are so thin that under influence of a high pressure connection, they are cut through with only minimal pressure. - Plating or coating treatments under aluminum or steel are useless as an aid to connection, since a) it is likely that it will be required to clear the paint under the screw head/lockwasher anyway, and b) the extreme pressure presented by the points of the lockwasher will cut through the coating and into the base metal. The main purpose for these coatings is paint adhesion. Proper paint adhesion to metal requires a conversion coating. For steel, phosphatizing is commonly used. For aluminum, Alodine chromate conversion is one of the common ones. For zinc or cadmium plated steel, a chromate conversion coating is used. But this is a paint adhesion issue, and as pointed out above, these have no effect on a high pressure connection. - Basically, as far as the electrical interface is concerned, plating on the screw and the lockwasher is irrelevant. The interface is gas-tight. An unplated screw will look like hell after a while, but that is another issue. When tightened, the points of the lock washer will cut through ANY plating present and make a gas-tight interface, so your plating choice should be made based on galvanic compatibility issues, not electrical connection issues. But all this above assumes that paint is masked under the screw/lockwasher interface. It is not a matter that with any paint system, and any reasonable sized screw/lockwasher (say, #6 or larger), there is no way that a good electrical connection cannot be made if the screw is fully tightened! And if the screw is NOT fully tightened, then you cannot guarantee a good connection, no matter what interface arrangement is used. It is simply that regulatory agencies are unlikely to accept this relatively obvious reality, and that they will insist that paint masking is needed. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Wells [mailto:cdwe...@stargate.net] Sent: March 21, 2002 4:40 PM To: 'emc-pstc' Subject: chassis bonding - star washers enough? Looking for some feedback on bonding various parts of a painted
RE: SND/ND ratio
Could this be a weird abbreviation for Signal to Noise ratio? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: richwo...@tycoint.com [mailto:richwo...@tycoint.com] Sent: March 21, 2002 7:29 AM To: emc-p...@majordomo.ieee.org Subject: SND/ND ratio The term SND/ND ratio is used in ETSI EN 300 220-1 as one of the performance criteria for receivers. Can someone tell me what this term means? Richard Woods Sensormatic Electronics Tyco International --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Relative merits of various logic families in not generating RFI
I generally agree, although your comment that double sided PCBs are about to disappear is rather premature. Way over half of the PCBs manufactured in the world today are SINGLE sided (look in any piece of high volume electronics). Double sided PCBs still will be used in volume for many years to come. Many 4 layer PCBs are simply the result of lack of designer layout skill, or (in particular) a result of the use of autoplace and autoroute programs that would otherwise ventilate a 2-sided board with an absurd number of vias and serpentine tracks snaking willy-nilly all over the place. The solution to the need for actual skill in board layout is often to let the machine do it, and suffer the cost of more layers. Time to market is, it seems, more important than cost or quality. At least here in North America. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Cortland Richmond [mailto:72146@compuserve.com] Sent: March 19, 2002 4:02 PM To: Robert Macy; ieee pstc list Subject: Re: Relative merits of various logic families in not generating RFI Probably, you won't get much choice. I've often found older, slower, quieter logic impractical or even uneconomical to use. It may be made only by one (thus off limits single-source) manufacturer, or it may be built using older, more expensive technologies and cost an arm and a leg. And it may happen one day that a manufacturer lets you know production is simply ending, and with no chance of an equivalent substitute. I am rather afraid that the best solution in these cases is to go with later, even if noisier devices -- and then design for them. Then too, if you use current devices, you may escape being blind-sided when they go to a smaller fabrication technology without letting you know. Even spting advertised an spe'd as an older device may in fact be a newer one. Who, after all, specifies devices by the fastest they go? It's always a minimum guaranteed speed. Yes, that means even MHz and KHz clock-rates with nanosecond transitions. You have to deal with it. Slew rate limiting is available, sometimes, built-in. If not, you have to add it externally. I've seen a 30 dB difference at 147 Mhz from a single 33 ohm resistor on a 1 Mhz clock. You have to be more careful with layout. You have to avoid inadvertent peaking networks - DON'T let anyone just throw HF bypasses willy-nilly on logic signals; you'd be AMAZED where the high frequencies can end up. And it means the end, really of 2-layer boards, at least as the old engineers know them. They have to be redesigned for RF, even if we weren't dealing with RF. But in the end, we get reliable boards, cheaper, that won't have to be replaced when the foundry discovers shorter-wavelength lithography. And your totem-pole short circuit? Yes, they know about that. Don't DO it. (grin) If you MUST have that kind of output, put a charge reservoir right at the device power pins, faster than a speeding junction, able to leap tall short circuits at a single bound, with enough charge to keep the transient local. But you already KNEW that! Cheers, Cortland --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Conductive Coatings/Conductive Plastic
I've had a fair amount of experience with both conductive plastics, and conductive coatings. Your comments are basically correct. A lot depends on what you are trying to achieve, both in terms of attenuation at a particular frequency, and how much actual attenuation you need. In one project I was involved with, we needed around 60dB of attenuation at 400 MHz. Conductive plastics were mostly useless, although the ones that were best (but still not good enough) were those filled with long strand stainless steel. As you mention, one of the big problems is making contact, since there tends to be a microscopic film of insulating plastic formed over the surface of the molded object. In this project, we achieved excellent results with selective electroless copper plating (covered with a thin flash of nickel for corrosion resistance). Similar excellent results were obtained using Spraylat's non-corroding copper paint. The results were almost identical to using a die cast aluminum case at this frequency (the device was a 416 MHz, 5 Watt, hand held search and rescue satellite transmitter). The usual nickel-bearing paints were useless at this high frequency, and carbon-bearing paints were absolutely hopeless. The high resistivity of both relegates them to low frequency, low attenuation requirements. Another reasonable choice is Zinc Arc Deposition. Even though zinc has relatively poor conductivity, this process lays on so much of the stuff (up to 0.1mm, or 0.004), that the overall resistivity is relatively good. Of course, the extra thickness can cause other problems in assembly and so on. As far as conductive plastics are concerned, we found that the best (but still not great) results were obtained with high percentages of LONG STRAND stainless fiber content. Toshiba's EMI CLEAR line of resins also seemed somewhat promising. But one significant problem with these and other filled conductive resins is that the surface finish is lousy. In general, they require painting (with masking of the critical areas) after moulding to be presentable, and this costs almost as much as simply spraying a decent conductive coating on ordinary plastic, which would work better anyway! Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: John Juhasz [mailto:jjuh...@fiberoptions.com] Sent: March 19, 2002 5:42 AM To: 'emc-p...@ieee.org' Subject: Conductive Coatings/Conductive Plastic Seeking comment on Conductive Coatings vs. Conductive Plastic Having dealt with metal (primarily steel) enclosures, my knowledge of conductive coatings/conductive plastics is strictly based on what I have been able to gleen from simple research and some conversation. It is my understanding the conductive plastic (metal fibers mixed with the plastic) is less effective at high frequencies ( 200MHz) than plastic with a conductive coating (i.e. electroless plating). Further, from a processing perspective (notwithstanding the shielding effectiveness), if good contact between mating pieces is required, conductive plastic is not a top ranked choice - the amount of fiber that is actually exposed to make contact is difficult to control and filing during product assembly may be required to expose sufficient fiber. And in both cases - SE and physical contact - the preparation (mixing) of the plastic/metal fiber needs to be tightly controlled (and is more difficult to control), with potential for greater variances from to batch to batch than there is for plated plastic. Comments please. GE Interlogix John A. Juhasz Product Qualification Compliance Engr. Fiber Options Div. Bohemia, NY 11716 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher:
RE: product modifications by the end user
One solution that would soon get rid of the problem at its source, would be to have the Marketing Moron do a few of the upgrades himself. With any luck, he would find out firsthand the effects of electrical current flow through the human body. :) Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Colgan, Chris [mailto:chris.col...@tagmclaren.com] Sent: March 19, 2002 4:36 AM To: 'Emc-Pstc' (E-mail) Subject: product modifications by the end user Hello good people Just say someone in your marketing department came up with the bright idea of selling upgrade kits to an unqualified, untrained end user that involved removing the top cover of a product. In the process not only would the victim be exposed to hazardous voltages (if the product was still connected to the mains) but he/she would also have to wire up mains connections. There would also be a possibility that critical insulation would be disturbed. Apart from telling them that they were mad and suggesting that someone could be killed or seriously injured, would there be any black and white legislation that you could use to help bin this idea? I can't find anything specific in EN60065 or the LVD. Thanks for any input Chris Colgan Compliance Engineer TAG McLaren Audio Ltd The Summit, Latham Road Huntingdon, Cambs, PE29 6ZU *Tel: +44 (0)1480 415 627 *Fax: +44 (0)1480 52159 * Mailto:chris.col...@tagmclaren.com * http://www.tagmclaren.com ** Please visit us at www.tagmclaren.com ** The contents of this E-mail are confidential and for the exclusive use of the intended recipient. If you receive this E-mail in error, please delete it from your system immediately and notify us either by E-mail, telephone or fax. You should not copy, forward or otherwise disclose the content of the E-mail. TAG McLaren Audio Ltd The Summit, 11 Latham Road Huntingdon, Cambs, PE29 6ZU Telephone : 01480 415600 (+44 1480 415600) Facsimile : 01480 52159 (+44 1480 52159) ** Please visit us at www.tagmclaren.com ** --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: IP67 Water Ingress Testing
A trivially simple, non-costly pressure release mechanism is a piece of .020 or 0.040 GoreTex sheet covering a vent hole (about half an inch diameter). This will be totally waterproof to 4 meters depth (I designed a patented hydrostatic release mechanism used on a popular shipboard EPIRB rescue beacon that uses this very principle). The GoreTex is impermeable to water at reasonable pressures, but easily passes gasses, thus as far as the water is concerned, the housing is sealed; but the battery can vent easily. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: McKinney, Alex [mailto:mckinne...@ems-t.com] Sent: March 14, 2002 11:51 AM To: IEEE EMC-PSTC Forum (E-mail) Subject: IP67 Water Ingress Testing All, We are currently working on a new handheld product that will be tested for IP67 Water Ingress (1 meter submersion for 30 minutes) and we are trying to determine the safety impact of not including the lithium ion battery pack as part of this rating. This product will be UL60950 Listed. One question that has also been asked of me is whether this battery pack needs to be vented. A few lithium ion cell manufactures whom I have researched on this say that the pack should definitely be vented. If vented then the IP67 rating on the battery pack is definitely out of the question without designing some costly pressure release mechanism. I guess my ultimate question is, how safe is a lithium ion battery pack if water is introduced in to the circuit? Any help is greatly appreciated. Regards, Alex McKinney Safety Engineer LXE, Inc. Tel: 770-447-4224 x3606 Fax: 770-447-6928 --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Wire spool labeling requirements
Illogical bureaucracy perhaps? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: March 12, 2002 3:26 PM To: emc-p...@ieee.org Subject: Wire spool labeling requirements Over the years, there is a question that has plagued me (there are many others). This one is just a curiosity and maybe someone in this group knows the answer. Four times a year we are audited for our NRTL certifications and the inspector makes it clear that using wire in our products with the UL recognition and CSA certification marks is not sufficient. Even though we have incoming inspection records, it seems they always want to see the wire spool in our stock rooms and make sure it has the proper labels. I understand all the concerns with using an approved respooling house to maintain the integrity of the wire. What I don't understand is how a simple adhesive label on the spool is better evidence than the embossed markings that appear along the entire length of the wire. It seems to me that if someone wished to fraudulently mark a wire as approved material, the labeling of the spool is easily done and would be the least of their worries. Can anyone explain the history behind this requirement? thanks, -doug --- Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. Mail stop: 203024 1626 Sharp Point Drive Ft. Collins, CO 80525 970.407.6410 (phone) 970-407.5410 (fax) mailto:doug.pow...@aei.com --- _ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Don'r Get Caught Running a Red Traffic Light!
Once again, the legal system scores a victory over common sense! Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Bill Owsley [mailto:ows...@cisco.com] Sent: March 8, 2002 7:15 AM To: Doug McKean; ieee pstc list Subject: Re: Don'r Get Caught Running a Red Traffic Light! Don't know about CA, but in this state, yes, a driver would get a ticket. Drivers are required to yield as long as they don't break a law. At 08:37 AM 3/8/2002, Doug McKean wrote: Just as a side issue about remote monitoring of red-light runners ... One unintended consequence of cameras watching for people who run lights happened in Fremont about 2 years ago. A couple of stop lights were set up with cameras as an experiment. During the course of rush hour traffic one day at one of the experimental camera sites, an emergency vehicle was stuck behind several vehicles sitting for a red light. Apparently the fire truck was boxed in since the roads were several lanes wide and the truck was all the way over in a right lane. Lights and siren were blaring away. Q: Did any of the cars move out of the way of the fire truck and in doing so some would have to move through the intersection and thus thru the red light? A: No. Reason: No one wanted to get a ticket running the red light. Be rather ironic that the fire truck was responding to the home of someone sitting at that intersection. Just something to think about. Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: EMC and Safety PCB Reviews
Keyboard Engineer?! That's a good one. Must remember that! Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Stephen Phillips [mailto:step...@cisco.com] Sent: March 7, 2002 12:27 PM To: Robert Wilson Cc: emc-p...@majordomo.ieee.org Subject: RE: EMC and Safety PCB Reviews Technically, we refer to them as PCB CAD engineers. I omitted part of that, given the fact that it seemed redundant - PCB's being the topic of discussion. I now return you back to your job as Keyboard Engineer. Stephen At 11:59 AM 3/7/2002, Robert Wilson wrote: As a side issue to your comments, I find it interesting that you refer to a PCB designer as a CAD engineer . Does this mean that 20 years ago he would have been a Drafting Board engineer ? :) Kind of sad when the tool one uses is deemed to be more important than the job one is doing! Bob Wilson TIR Systems Ltd. Vancouver.
RE: EMC and Safety PCB Reviews
As a side issue to your comments, I find it interesting that you refer to a PCB designer as a CAD engineer. Does this mean that 20 years ago he would have been a Drafting Board engineer? :) Kind of sad when the tool one uses is deemed to be more important than the job one is doing! Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Stephen Phillips [mailto:step...@cisco.com] Sent: March 6, 2002 9:49 AM To: Alex McNeil Cc: emc-p...@majordomo.ieee.org Subject: Re: EMC and Safety PCB Reviews Alex, Not really a thorough checklist per se, but for Safety - roughly this: Throughout this process, I prefer to make notes on paper doc's, and then sit with the CAD engineer to go over the review on his computer screen and make any changes right then. - Schematic review (identify and mark up areas such as exceeding SELV and TNV, identify critical nets). - Provide Creepage Clearance guidelines to PCB CAD engineer (who inputs into the CAD system, based on properties assigned to the nets via the schematic). - Placement Review (using marked up silk-screen or assy. dwg based on previously marked up schematics), and also layer stack-up review at this time. - Layout review, layer by layer routing, and adjacent layer to layer. - Layout review with mechanical dwg superimposed (since sheet metal could violate CC to the PCB). - Thieving review (since thieving could violate CC). - Photo Artwork review (especially planes). - Also make sure the drawings tell the PCB fab. vendor not to put their logo smack in that nice clearing which is your CC! Obviously I left out a lot of the detail as to what we design for and what we specifically look for, but these are the higher granularity steps I routinely take. EMC would take more or less the same steps, just with different criteria. I hope this helps, Stephen At 09:46 AM 3/6/2002, you wrote: Hi Guys, I am being asked to review PCB's for EMC (and Safety) acceptance. I was going to try and collate a check list then I thought of this wonderful forum!! Does any kind person have such a thing as an EMC PCB Design Check list? Does any kind person have such a thing as an Safety PCB Design Check list? Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com
RE: Don't Get Caught Running a Red Traffic Light!
And not least, for pole-mounted red light cameras, you need shotgun protection. :) The first red light camera installed here (Vancouver) was dealt with rather quickly in this manner. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Johnson [mailto:john...@itesafety.com] Sent: March 6, 2002 12:23 PM To: 'Peter Merguerian' Cc: emc-p...@majordomo.ieee.org Subject: RE: Don'r Get Caught Running a Red Traffic Light! Peter, For your equipment special consideration of transient levels is needed. Refer to annex G of 60950. If you power the pole mounted equipment from overhead lines as do streetlights, you are likely to be overvoltage category IV which might mean mains transient levels of 4 or 6 KV. If the camera is remotely powered from inside a building, you might treat the installation as TNV3, where 1.5 KV is the assumed transient level (2.10.3.3 note 2) unless you know otherwise. Don't forget you need lightning protection considerations. (References are to IEC 60950-1 (2001-10) Ed. 1.0) Bob Johnson ITE Safety --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Laser Safety
Regarding the comment John made (snipped below), I think that in some regards, regulatory warnings are partially to blame for installers/users not paying proper attention to safety requirements. In North America, the tendency is to require verbose, rambling warnings that tend to include so much redundant or even irrelevant information that the user just ignores them. This is in general contrast to the tendency in Europe, where warnings are kept short and punchy, or even totally replaced by eye-catching symbols. One can imagine ol' Bubba the installer faced with a warning containing a paragraph of legalistic run-on sentences that cannot seem to get to the point in a concise manner. He is simply going to ignore the whole thing. A case in point is the FCC Class B warning on consumer electronic equipment. Is there anyone on the planet who has actually bothered to fully read this warning? Seems to me that this is a general problem that ought to be addressed. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: John Juhasz [mailto:jjuh...@fiberoptions.com] Sent: March 6, 2002 6:17 AM To: 'Mark Schmidt'; emc-p...@majordomo.ieee.org Subject: RE: Laser Safety [Snip] In my opinion, whether or not the installers/service/end-user is trained or not (sometimes the trained are worse because they tend to be over-confident and throw caution to the wind) it's worth marking the areas on/in the product as well as putting references in the manual. John Juhasz Fiber Options Bohemia, NY --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, )
More importantly, North American paper sizes are just plain irrational. At least the metric sizes all have the same aspect ratio, so enlarging/reducing from one size to another doesn't result in a large band of unused space. Even the US Patent Office has given up on US A (8-12 x 11) or US legal (8-1/2 x 14) size, and for at least 10 years, submissions have to be made on the metric A4 size paper that most of the civilized world uses. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: John Shinn [mailto:john.sh...@sanmina-sci.com] Sent: March 4, 2002 4:18 PM To: 'John Woodgate'; emc-p...@majordomo.ieee.org Subject: RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, ) Actually, US Legal size is 8-1/2 by 14 inches. 8-1/2 by 17 inches is B-size. John Shinn, P.E. -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of John Woodgate Sent: Monday, March 04, 2002 11:36 AM To: emc-p...@majordomo.ieee.org Subject: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, ) I read in !emc-pstc that david_ster...@ademco.com wrote (in 2DF7C54A75B dd311b61700508b64231002c5a...@nyhqex1.ademcohq.com) about 'Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, )', on Mon, 4 Mar 2002: It prints on legal (8-1/2 x 17) paper. That size is 'illegal' in Europe! (;-) -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surfaces, chassis, )
One must take care to separate fact from opinions. Mixing metals as you mention is NOT necessarily a sure way to promote corrosion. Yes, steel against aluminum us not good practice since they are far enough apart on the electromotive series that they will act as a local battery (in the presence of an electrolyte such as salt water), and the aluminum will corrode. Another bad pair is aluminum against copper alloys. But in a dry environment, no problem can occur since no moisture is present. Galvanic corrosion without the presence of an electrolyte is impossible. Other metal combinations are also problematic such as aluminum against zinc plated or galvanized steel (or zinc plated anything). Cadmium plated steel against aluminum is generally considered an acceptable combination, as is 300-series stainless steel against most metals. 300-series stainless (especially type 316) is considered relatively passive. One must simply choose the metal pairs carefully, taking into account the environment, and if necessary making sure they are sufficiently close in voltage potential to each other on the electromotive scale. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Wan Juang Foo [mailto:f...@np.edu.sg] Sent: February 28, 2002 11:12 PM To: emc-p...@majordomo.ieee.org Subject: RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surfaces, chassis, ) David, You mention that you have a Steel and Aluminium to content with. My opinion about mixing metal parts in an assembly (chassis) is a sure way of promoting corrosion, especially if the installation is in a humid environment. If you want the chassis to be a reliable electrostatic shield do not have panels that are made with different metal bolted to the 'frame' or chassis. Under some codes this is a 'No Go' area. BTW, I assume that you must be working with a small box, otherwise you would need much more than a 'rubber eraser' to clean the mating surfaces. All equipment metalwork should be electrically bonded in a manner which does not rely on 'hopeful' electrical conduction through anti-corrosive treatment like anodised aluminium and paint. Careful attention to the assembly process will weed out things like ball-bearings races, nylon runners and coasters, or other insulating materials. Conduction through painted panels should not be dependent on the gripping action of star washers. The design should be such that no currents flows in any part of the metal work. The objective is to ensure that any part of the metalwork can be relied upon as an effective electrostatic screen and not the reverse, a radiator. Tim Foo --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Use of PCB Traces as Fuse and Voltage suppressor
I can't verify the part that after a wrench was dropped on the -48V bus bars, all the other equipment was blown, but I can throw a little light on this. The previous company I worked for made Telco rectifiers. Our largest system had an output of over half a megawatt (!) at -48V. The bus bars were not little 1 diameter rods, but laminated copper bars that were 6 x 4 in cross section. One customer was worried about what would happen when ol' Bubba dropped his wrench across the bars, and I had to prove that the bars would not tear themselves loose due to the repulsive force caused by peak short circuit current from the batteries being charged by the rectifier system. The current was not insubstantial: 100,000 Amps would flow for about 15mS before the fuse cleared. It was assumed that not only would Bubba's wrench vapourize, but so would Bubba. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: February 25, 2002 10:34 PM To: Jim Bacher; ieee pstc list Subject: Re: Use of PCB Traces as Fuse and Voltage suppressor Jim, You touch on an important issue concerning a fuse - just how does it blow? Years ago I discovered by accident that fuses were designed with some remarkable properties, when we had to make our own transient generator to verify some telcom equipment's compliance to a BABT power supply transient spec. The BABT spec required that you simulate some very husky power transients. It was like a short occurs in adjacent electronics followed by the inductive kick. The -48 voltage would clamp to around 10 volts then pop up to over 300 volts capable of supplying 500A for something like more than 50mS. If you didn't design your protection properly you would have a lot of unintentional PCB trace fuses. [ Actually heard that the spec originated because a workman had dropped his wrench across the 1 inch diameter rods which supply the -48 to the telco building from the battery building. After the wrench evaporated, they found the whole room of equipment was blown, thus the spec. Somebody verify that? ] The simulator used 4 deep discharge current vehicle batteries supplying the telcom equipment through 50uH of inductance (that was cable on a spool). Parallel to that you used a starter solenoid to short out a fuse with a dead short. Amazingly the larger fuses never produced much kick back. They were designed to blow gently away. Tried all kinds. Most of the 8AG didn't do much, other types, nothing, even the 100 amp cartridge types, nothing, The absolute best was a 1A 8AG type. When that went, you'd get a flash of light, 300 volts trying to drive 500 amps into everything, and even the coil would jump up off the floor. Talk about PCB traces acting like fuses. Anyway, I learned a respect for people who design fuses to make them go away so gently when there is an incredible potential for some extremely high voltage transients. - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Jim Bacher jim.bac...@paxar.com To: 'Cortland Richmond' 72146@compuserve.com; Chris Maxwell chris.maxw...@nettest.com; ieee pstc list emc-p...@ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Monday, February 25, 2002 3:04 PM Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor Long time ago we found that the traces worked well as fuses when the batteries were fully charged. However, when the batteries were mostly discharged, the PC Board traces did not work well as fuses. At lower battery charge levels, the traces became very hot and ignited the PC Board rather than opening the traces up. I therefore would recommend against using PC Board traces as fuses. Jim Jim Bacher, Senior Engineer Paxar Corp. e-mail: jim.bac...@paxar.com or j.bac...@ieee.org voice: 1-937-865-2020 fax: 1-937-865-2048 -Original Message- From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Thursday, February 21, 2002 12:53 AM To: Chris Maxwell; ieee pstc list Subject: RE: Use of PCB Traces as Fuse and Voltage suppressor When do you need a fuse? Level II is the only time you are allowed to lose functionality, and the requirement for THAT is, it can't catch fire or explode. I've seen trace fuses tried. The problem comes after the trace blows. You are at the mercy of your board shop, and if you use a number of them, results might not be all that repeatable. AS i said earlier, I've had a board catch fire in my hand (though not as a result of stress, but a solder splash). It is instructive. Cortland --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To
RE: PCB floating area layout
My comments were more related to the situation of a floating ground that was not well grounded to the main ground. It seems to me that you may have a common mode noise problem. Noise is probably being coupled to the ground plane and using the shield on the DC cable as an antenna. Looping the wires that feed the D-sub in your unit) a couple of times around a lossy ferrite toroid is one way to decouple the cable's shield from the ground in your unit. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] Sent: February 25, 2002 4:14 PM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: RE: PCB floating area layout Jeeez, I have just the opposite problem GROUNDING a PCB at a certain location. The device is a metal enclosed digital device, about the size of a video cassett tape. Its powered by one of those small AC/DC power supplies like you have on your laptop computer. The DC power cable does have a shielded cable, with a drain wire in contact with the foil. Both are connected at shielded 9 pin D and grounded to the case. The other end however, is just a drain wire into the AC/DC supply. Its a plastic box. The PCB is grounded in several locations to the bottom of the metal enclosure, at roughly 37 cm (5 inches). At about 800 Mhz the thing radiates above class B by 3 or 4 dB. If I remove one of the ground points the signal drops 5 to 8 dB. Re-ground and its up, unground and its down. Guess, I should feel lucky. I can remove the ring and via so that it doesn't get grounded there and the problem is gone. I just get real nervous with that answer, but it works so the engineer boss is not to crazy about making any mods. Gary -Original Message- From: Robert Wilson [mailto:robert_wil...@tirsys.com] Sent: Monday, February 25, 2002 12:19 PM To: emc-p...@majordomo.ieee.org Subject: RE: PCB floating area layout Floating grounds on PCBs tend to be problematic, especially at high frequencies. Minimizing the effective capacitive reactance between the floating ground and the real ground will ensure that the floating ground is AC Cold. I don't just mean bypassing it with (say) a few thousand uF of electrolytic capacitance, but instead ensuring minimal capacitive reactance to ground across the entire frequency band of interest. This usually entails (as an example) paralleling something like a 0.1uF cap, and with an NP0 1000pF cap (or similar). If the floating ground not properly decoupled to the main ground, and it is a significant proportion of a HF wavelength, then it can have very high AC voltages superimposed and act as a marvelous antenna. Reducing the size of the floating ground is always a good plan. Increasing it merely means that you have a larger potential antenna. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Paolo Peruzzi [mailto:paolo.peru...@esaote.com] Sent: February 25, 2002 7:34 AM To: emc-p...@majordomo.ieee.org Subject: PCB floating area layout Hi all, I'm dealing with a PCB that has a floating section isolated from the rest of the board for safety purposes (patient applied part). I found out some problems with emissions, due to the coupling between the floating part and of the PCB and the earthed one. My questions are concerning the layout design of the floating area: 1) Is it best to minimize the HF capacitive coupling between the earthed ground and the floating ground or to maximize it? 2) Is it best to reduce the amount of the floating ground or to increase it? Does it depend on the goodness of the main ground, i.e. how much it is cold ? (I see the board as a dipole with one end connected to earth, and the other floating). Thanks, p.p. - ESAOTE S.p.A. Paolo Peruzzi Research Product DevelopmentDesign Quality Control Via di Caciolle,15tel:+39.055.4229306 I- 50127 Florence fax:+39.055.4223305 e-mail: paolo.peru...@esaote.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc
RE: PCB floating area layout
Floating grounds on PCBs tend to be problematic, especially at high frequencies. Minimizing the effective capacitive reactance between the floating ground and the real ground will ensure that the floating ground is AC Cold. I don't just mean bypassing it with (say) a few thousand uF of electrolytic capacitance, but instead ensuring minimal capacitive reactance to ground across the entire frequency band of interest. This usually entails (as an example) paralleling something like a 0.1uF cap, and with an NP0 1000pF cap (or similar). If the floating ground not properly decoupled to the main ground, and it is a significant proportion of a HF wavelength, then it can have very high AC voltages superimposed and act as a marvelous antenna. Reducing the size of the floating ground is always a good plan. Increasing it merely means that you have a larger potential antenna. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Paolo Peruzzi [mailto:paolo.peru...@esaote.com] Sent: February 25, 2002 7:34 AM To: emc-p...@majordomo.ieee.org Subject: PCB floating area layout Hi all, I'm dealing with a PCB that has a floating section isolated from the rest of the board for safety purposes (patient applied part). I found out some problems with emissions, due to the coupling between the floating part and of the PCB and the earthed one. My questions are concerning the layout design of the floating area: 1) Is it best to minimize the HF capacitive coupling between the earthed ground and the floating ground or to maximize it? 2) Is it best to reduce the amount of the floating ground or to increase it? Does it depend on the goodness of the main ground, i.e. how much it is cold ? (I see the board as a dipole with one end connected to earth, and the other floating). Thanks, p.p. - ESAOTE S.p.A. Paolo Peruzzi Research Product DevelopmentDesign Quality Control Via di Caciolle,15tel:+39.055.4229306 I- 50127 Florence fax:+39.055.4223305 e-mail: paolo.peru...@esaote.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Potentially Explosive Atmospheres
This may seem like a dumb question, but how would a cellphone pose a hazard? I am unaware of anything in a cellphone that can cause any kind of a spark or arc that might start combustion in such an atmosphere. Certainly none of the keypad contacts could cause a problem. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: ron_cher...@densolabs.com [mailto:ron_cher...@densolabs.com] Sent: February 21, 2002 10:55 AM To: emc-p...@ieee.org Subject: Potentially Explosive Atmospheres Hi, I am trying to find in the UL specifications where a cell phone manual must contain a warning to the user on using the phone in a potentially explosive atmosphere. Thanks in advance, Ron Chernus Compliance Engineer, DENSO --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: South Korean Power System Schuko Plugs
The inability of Schuko plugs to be able to be polarized, may have something to do with the fact that German homes (at least) are supplied with 3-phase power. Some time ago this came as a surprise when a friend was showing me his new lathe he had just installed in his basement, which used a 3-phase motor. When I asked how he managed to get 3-phase power installed in his house, he gave me that what planet did you come from look, and said that this is how power is delivered to all residences there. My recollection from our conversation is that at least some of their domestic 3-phase power systems use the Delta configuration, so outlets are connected across 2 of the 3 phases. Thus, there is no neutral or polarity. I wonder if anyone can verify if they use a Delta or a Y connection? Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Allen, John [mailto:john.al...@uk.thalesgroup.com] Sent: February 21, 2002 12:32 AM To: Robert Wilson; emc-p...@majordomo.ieee.org Subject: RE: South Korean Power System Schuko Plugs Hi Folks A few years ago I worked for BSI Technical Help to Exporters and helped to update their publication World Wide Plugs and Sockets Survey - which I assume is still available from BSI (see www.bsi-global.com) I remember looking at the Korean standards for plugs and sockets:- Yes - they were/are variations of Schuko types(both with and without earthing contacts), but I also seem to remeber some NEMA (USA/Canadian) types as well. However, as part of another large exercise for a customer I reviewed many of the European wiring rules standards to identify any conventions or requirements for the polarity of wiring-up of sockets - notably those that accept the various versions of the (generally reversible) Schuko plugs and also the somewhat similar Danish, Swiss and Italian plugs. Result : there were (and presumably still are) wiring colour codes for the building wiring to these sockets - BUT NO CONVENTION AS TO WHICH COLOUR IS CONNECTED TO WHICH CONTACT TUBE OF THE SOCKET, apart (obviously) from the requirement that the Green/Yellow insulated conductor be connected to the earthing contact. Therefore you must always assume that the Line/Neutral polarity of the wall socket is random - this is also true for the French version of the socket with the earthing pin projecting out since it is only a (more recent?) variety of the type of socket which has no such pin. Thus the equipment connected to it must have some sort of double-pole disconnect device (be it a switch, or the plug itself). Double-pole fusing requirements may depend on the product standard requirements, but is effectively required where the internal wiring of the equipment cannot deal with the full prospective fault current available from the wall socket. Hope this clarifies matters. Regards John Allen Thales Bracknell, UK. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: South Korean Power System
Since the Japanese use the North American style plug (seems an odd choice since it is so flimsy in comparison to other types they could have used), it's probably a good bet that the Koreans us this as well. I'd be surprised if they used the Schuko plug. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: February 20, 2002 12:21 AM To: emc-p...@majordomo.ieee.org Subject: Re: South Korean Power System I read in !emc-pstc that Price, Ed ed.pr...@cubic.com wrote (in b78135310217d511907c0090273f5190d0b...@curly.ds.cubic.com) about 'South Korean Power System', on Tue, 19 Feb 2002: Are both wires floating off of ground? Or is one of the power conductor wires tied to safety ground? And, if one conductor is grounded, as you face into a socket, is it the left or right contact? If the 3-contact connector really is a Schuko, the plug can be inserted either way round, so you have to treat both power contacts as live. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk After swimming across the Hellespont, I felt like a Hero. PLEASE do NOT copy news posts to me by E-MAIL! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Japan mains voltage
One of the Japanese islands also has a 50Hz power grid. Apparently it's a real dog's breakfast there, as far as AC power systems are concerned. The voltage is 100 V, not 110V (as the original poster had mentioned). Bob Wilson TIR Systems Ltd. Vancouver.
RE: Chamber Doors
With regards to beryllium fingers, they are not beryllium. They are an alloy of copper and beryllium, with the standard C17000 alloy containing only 1.7% beryllium. There is no danger in simply handling these fingers. To be sure, there is a danger in breathing in dust from machining actual beryllium. This danger is less for Be-Cu alloy (owing to the low beryllium content). But this is not particularly relevant here because it is unlikely that any operation will be carried out that can create any significant beryllium dust when simply cleaning Be-Cu fingers. Further, these fingers are generally plated with another metal to eliminate poor contact due to tarnishing or corrosion, so one is generally not even touching the Be-Cu alloy at all. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Wan Juang Foo [mailto:f...@np.edu.sg] Sent: February 19, 2002 2:08 AM To: ieee pstc list Subject: Re: Chamber Doors The other problem could be that whoever build the chamber did not make the door. They buy it off from someone else and the warranty is only one year. :-) One year seems to be reasonable period considering that there is a number of things that can go wrong with moving parts that are constantly held under pressure. BTW, 'Be' (Beryllium) is a highly toxic metal that will not get out of your blood once it enters it. I would strongly advise anyone cleaning their Be-Cu finger stocks from exposing themselves to any possibilities of cuts or abrassions while cleaning these 'fingers'. I understand the concentrations of Be is low but why would anyone take the risk of prolonged exposure to Be dust and metal chippings? Tim Foo --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: Resistors pulse loading capabilities
I suspect that this will depend very strongly on the characteristics of specific type of resistor. Further, there will undoubtedly be very significant differences from manufacturer to manufacturer, in the ability to absorb stresses well beyond normal design intent. I think it would be rather hard (or even perhaps impossible) to make generalizations that would apply to, for example, all 1 Watt resistors. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Massimo Polignano [mailto:massimo.polign...@esaote.com] Sent: February 18, 2002 6:03 AM To: emc-p...@majordomo.ieee.org Subject: Resistors pulse loading capabilities Does anybody out of there know what are the methods to evaluate resistors pulse loading capabilities (maximum peak pulse voltage without failing to open circuit)? Is there any standard models? This could be very useful to design the power supply circuit parts involved in a surge immunity test. Thanks in advance. m.p. - ESAOTE S.p.A. Massimo Polignano Research Product DevelopmentDesign Quality Control Mngr Via di Caciolle,15tel:+39.055.4229402 I- 50127 Florence fax:+39.055.4223305 e-mail: massimo.polign...@esaote.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: [URGENT] Need some information about NEBS..
Without getting into details, the main point is that it is brutal (and even that is an understatement), and it is expensive. A full-on test involves everything from EMI compliance, to earthquake testing, to flame and fire tests. Costs can easily run to US$100,000 and time to do the test can range from 6 weeks to months. There are several independent test labs in the US that can do the testing. I have not personally put any equipment through NEBS, but last spring I spent a couple of days at a test lab in the San Francisco Bay area (MET Labs) looking at their capabilities and how NEBS would impact the design of our telecom power electronics equipment. Perhaps others with more actual testing experience may be able to fill in the details. Bob Wilson.
