RE: ventilation holes
George - Please keep in mind that SELV alone, while addressing electric shock, does not address risks of fire. If, however, the external power supply complies with the requirements of a Limited Power Source, then you're home free, in terms of complying with the safety standard(s) (the enclosure becomes purely decorative). If the power supply in combination with the first circuit element or so in the power input circuitry inside the box cause the power source to comply with the requirements of a LPS, you'll need to have an electrical enclosure around the nonLPS supplied portions of the interior. You may want to further consider the long term effects on reliability and returns due to ingress of liquids, dust or other solid matter into the box. Oh, and thar's that EMC thangy I keep a-hearing 'bout. ;) Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services peter.tar...@sanmina-sci.com -Original Message- From: George Stults Sent: Tuesday, February 26, 2002 10:24 AM Hi Folks, I have a safety question for the group. I have a small (about 8 x 10 x 2 inch) piece of ITE equipment, SELV, enclosed in a plastic case, powered by an external 12 volt brick from AC mains. The problem is, the device tends to run a little hotter than desired. One proposed solution is to cut some vent holes in the top. These would be roughly (1/2) inch long by (1/6) inch wide, spaced (1/4) inch apart, running across the top near the front of the device. I haven't seen many (any?) devices with vent holes in the top, so I'm wondering if there is a basic reason why not, such as the cover must shed water, etc. My questions are, what considerations arise and what sections of EN 60950 apply to this, either to allow it or to exclude it. Thanks in advance George S. --- 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
Looking for reliable Scope repair
I hate to impose on the group but - - Can anyone recommend someone (in USA) to repair a minor sweep / trigger problem in my personal 465 Tektronix scope. It's an old friend and I can't afford a new one. A local company want's $200 Evaluation fee just to put it on the bench. I would appreciate any recommendations on affordable repair. Please reply to me directly. Thanks to all. Michael Taylor mtay...@hach.com - - or - 970-663-1377 ex.2646 Colorado
Re: ventilation holes
Hi David: You probably already know this, but don't forget that the product will need to pass temp tests during abnormals i.e., blocked vents. I'm not sure if pass temp tests means compliance with the heating requirements or the abnormal requirements, so I offer this clarification. Under abnormal conditions (blocked vents), there are no temperature limits per se. According to Sub-clause 5.4.1, under abnormal conditions the unit must remain safe. Best regards, Rich --- 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: UL Material flammability requirements for enclosures less than .3
Hi Paul: Can anyone give me any information on whether a box with less than .33 cubic feet needs to meet UL Flammability ratings? I have been told this is true, but I can not find the location of that information. I believe the requirement you are referring to is Sub-clause 4.3.3, UL1950/IEC 60950 Sub-clause 4.7.3.3, UL 60950-1/IEC 60950-1 This requirement exempts materials and components within an enclosure of 0.06 m^3 from flammablity requirements. The enclosure itself must be of metal and must have no ventilation openings. However, 0.06 m^3 = 2.12 ft^3 0.33 ft^3 = 0.01 m^3 so the volume you quote does not agree with the volume in the requirement. With this exception, and as far as I know, requirements for material flammability ratings are based on the circuit parameters, not on volume of the box. Best regards, Rich --- 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: ventilation holes
You probably already know this, but don't forget that the product will need to pass temp tests during abnormals i.e., blocked vents. Regards, David Lohbeck --- 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: In Line Fuseholder
Hi Bill Both Littelfuse and Wickmann Werke have these fuses Good Luck Kim Boll Jensen Bolls Raadgivning, Denmark Bill Wilson skriver: HELP!!! I'm looking for a UL R/C, 250V in line fuseholder for 5X20mm /or .25X1.25 fuses. There are a lot of 32Volters out there, but not 250V. Any assistance will be greatly appreciated.Bill Bill Wilson W.W.Wilson Associates 508-651-1388 wwwil...@rcn.com www.wwwilsonassoc.com attachment: kimboll.vcf
UL Material flammability requirements for enclosures less than .3 3 cubic feet.
Can anyone give me any information on whether a box with less than .33 cubic feet needs to meet UL Flammability ratings? I have been told this is true, but I can not find the location of that information. If possible can you give the exact UL specification this information can be found? I have reviewed UL1950 and have not found that information. Many thanks, Paul Denomme Viasystems Design Engineer paul.deno...@viasystems.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: ventilation holes
Hi George: I have a safety question for the group. I have a small (about 8 x 10 x 2 inch) piece of ITE equipment, SELV, enclosed in a plastic case, powered by an external 12 volt brick from AC mains. The problem is, the device tends to run a little hotter than desired. One proposed solution is to cut some vent holes in the top. These would be roughly (1/2) inch long by (1/6) inch wide, spaced (1/4) inch apart, running across the top near the front of the device. I haven't seen many (any?) devices with vent holes in the top, so I'm wondering if there is a basic reason why not, such as the cover must shed water, etc. My questions are, what considerations arise and what sections of EN 60950 apply to this, either to allow it or to exclude it. Top openings are specified in Sub-clause 4.6.1, 4.6.4, and Annex T of IEC 60950-1. There are no restrictions on openings if the source (brick) is SELV and LPS and the unit is intended for indoor use, i.e., does not need to be protected against ingress of water. You told us the source is SELV, but you did not tell us whether the source is also LPS. If the source is both SELV and LPS, then there are no restrictions on opening sizes. Indeed, there is no requirement for an enclosure. (With SELV and LPS supply, there is no shock or fire hazard, and the enclosure is not required to prevent access, ingress of foreign objects, or containment of fire.) If the source is SELV but not LPS, then the top openings cannot exceed 5 mm maximum dimension, or 1 mm maximum width. Generally speaking, physically small devices are also low- power devices. Consequently, they require little or no cooling that would require ventilation openings. So, for physically small products, there are no openings in the enclosures. Best regards, Rich --- 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
Standards Listing
Thanks to all who responded John Richards Customer Assurance Engineer Eurotherm Drives Limited --- 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
ventilation holes
Hi Folks, I have a safety question for the group. I have a small (about 8 x 10 x 2 inch) piece of ITE equipment, SELV, enclosed in a plastic case, powered by an external 12 volt brick from AC mains. The problem is, the device tends to run a little hotter than desired. One proposed solution is to cut some vent holes in the top. These would be roughly (1/2) inch long by (1/6) inch wide, spaced (1/4) inch apart, running across the top near the front of the device. I haven't seen many (any?) devices with vent holes in the top, so I'm wondering if there is a basic reason why not, such as the cover must shed water, etc. My questions are, what considerations arise and what sections of EN 60950 apply to this, either to allow it or to exclude it. Thanks in advance George S. --- 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
Seeking Requirements for Electric Wheelchair/ATV ??
Hello All, Are there any US and/or Canadian electrical safety requirements (beyond battery charger concerns) for electric vehicles -in this case - a vehicle that's cross between an electric wheelchair and an ATV (off-road, all terrain vehicle) Also interested in any other regulatory requirements that may apply to this sort of product. ThanX in advance, Art Michael Int'l Product Safety News A.E. Michael, Editor 166 Congdon St. East P.O. Box 1561 Middletown CT 06457 U.S.A. Phone : (860) 344-1651 Fax: (860) 346-9066 Email : i...@safetylink.com Website: http://www.safetylink.com ISSN : 1040-7529 --- 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
Automotive EMC
Try the following: http://europa.eu.int/eur-lex/en/lif/dat/1995/en_395L0054.html http://www.vca.gov.uk http://www.mira.co.uk/certification/ Regards Keith --- 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: ESD Generator confidence test - Pelligrini Target
Just one comment on the Pelligrini Target: We compared different Pelligrini Targets that were all made to the specifications. - Up to 1 GHz they perform reasonably close - Above 1 GHz large differences show up, although they are all made to the drawings. - All of them show resonances in their S21 above 1 GHz. - The input impedance goes up into the kOHm range, i.e., the current that is injected is very different from the current that would be injected into a large ground plane. Consequence === If you use a scope with 1 GHz bandwidth, the Pelligrini Target is good. That is what it was designed for. If you use a scope with 1GHz bandwidth, you should use a better target AND characterize the frequency response of the target - attenuator - cable chain. The differences between a good target and the Pelligrini target will get worsen if: - you use larger bandwidth - you analyze the current derivative or the ringing on the rising edge. Regards David Pommerenke --- 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:RE: ESD Generator confidence test
We also have come up with a simple way to test our ESD gun, but it requires the help from our lab assistant (lab managers work good too). First, have them take off their shoes and socks and stand on the Ground Reference Plan. Have them wet their fingers and grab the end of the ESD gun. Crank up the gun to 16.5KV single shot and let them have it. If the ESD gun is working properly, they will fall to the floor quivering slightly. Then they will wet their pants and forget who they are for about 25 to 30 minutes. Keep in mind that this method is not yet approved by A2LA or NAVLAP. Have fun, Brian --- 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
In Line Fuseholder
HELP!!! I'm looking for a UL R/C, 250V in line fuseholder for 5X20mm /or .25X1.25 fuses. There are a lot of 32Volters out there, but not 250V. Any assistance will be greatly appreciated. Bill Bill Wilson W.W.Wilson Associates 508-651-1388 wwwil...@rcn.com www.wwwilsonassoc.com
RE: Vehicle EMC and Safety standards
Hi Alex, The EMC standards governing vehicle electrical sub-assemblies (ESAs) are as follows: 1 - Radiated emissions - 95/54/EC (automotive directive) and CISPR 25 2 - Conducted emissions - CISPR 25 ( omitted by directive ) 3 - ESD is governed by ISO 10605. The test levels are 15kV air discharge for ESAs that can only be accessed from inside the vehicle and 25kV for ESAs that can be accessed from outside the vehicle (e.g. through open window). Contact discharge is 8kV for points accessible during normal operation. 4 - Fast transients and Bursts are replaced by ISO 7637/SAE J1113/11 in the form of test pulse 3a and Test pulse 3b 5 - Surge immunity is replaced by the automotive load dump, ISO 7637 Test pulse 5. This is the most destructive of the transients. 6 - Transient immunity is completed by the other test pulses in ISO 7637 (test pulse 1,2, 6) Test pulse 4 simulates the supply transient during cranking. You may want to look closely at the behaviour of your machines during this phase as access to memory can often result in corruption of data. Additional requirements may exist like twice the supply voltage for a jump start on a 12V battery. Note that the transient test levels specified for 12V and 24V vehicles are different and governed by ISO 7637-1 and ISO 7637-2 respectively. 7 - Radiated immunity - ISO 11452. Minimum test level is 25V/m (SAR) to meet requirements of the directive, but most vehicle manufacturers might ask for higher test levels like 50V/m and even 100 - 200V/m for safety critical ESAs. Frequency range is nominally 150kHz - 1GHz but it is common practice and vehicle manufacturers do tend to insist on tests starting at 10kHz. The Bulk current Injection test is also useful verification that you have left no stone unturned. It is described in detail in ISO 11452 Part 4 Depending on where your terminals will be fitted, the operating temperature range may change from the commercial, especially the lower limit which may have to shift from 0 to -40?C but I imagine you have accounted for this already and besides, financial transactions may be rather low on the list of priorities for a driver entering a cab at -40, but I haven't been to Russia on a cold day so ignore me. Of course I jest. For general safety, you will have to refer to the SAE standards. I cannot say for sure if EN60950 is adequate. http://www.sae.org/technicalcommittees/index.htm Hope this helps Regards - Chris Chileshe - Principal Electronics Design Engineer - Ultronics Ltd - http://www.senstronics.com -Original Message- From: Alex McNeil [SMTP:alex.mcn...@ingenicofortronic.com] Sent: Tuesday, February 26, 2002 11:35 AM To: 'emc-p...@majordomo.ieee.org' Subject:Vehicle EMC and Safety standards Hi Group, Our financial transaction terminals are mostly used in the commercial area e.g. shops and offices, which use a separate AC/DC power supply block connected to the mains There is a requirement for these same products to be used in vehicles e.g. Taxis and Buses. These would use the power from the batteries possibly from the cigarette lighter holder (12Volts). I have obviously had to design in additional filter circuitry to account for this type of DC Supply source. My question is, will there be additional EMC and Safety requirements in Europe or North America (other than those already approved for use in commercial areas) for vehicle/mobile use? Already Approved to: EMC: EN55022 Class B, *EN55024, EN6100-3-2, EN61000-3-3, FCC Part 15, ICES-003 Safety: EN60950 (also UL/CSA) *The only additional test I can think of is for the EN55024 to include the DC Power Port tests (excluded before due to the terminal being supplied from an AC/DC power source). As usual I look forward to your invaluable replies. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from th
Looking for a plug-in module for CDi1000
Hi good people, Would any of you guys out there happen to 'own' a 2x10uS module for the Compliance Design surge generator? I realize it is time to get away from this solution but we need a fast and hopefully inexpensive replacement immediately. Please respond to email below if you can help. Best regards, Phillip Godfrey Manager, Product Safety Nemko Dallas, Inc 802 N. Kealy Ave. Lewisville. TX75057-3136?xml:namespace prefix = o ns = urn:schemas-microsoft-com:office:office / www.nemkona.com email: outbind://2/phil.godf...@nemkona.com phil.godf...@nemkona.com Tel: (972) 436-9600 Fax: (972) 436-2667
RE: Vehicle EMC and Safety standards
Alex, For Europe, you need to check the Automotive EMC Directive 95/54/EC. It provides the EMC approval regime for motor vehicles of 4 wheels or more and all equipment (including aftermarket equipment) intended to be fitted in the vehicle. 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 -Original Message- From: Alex McNeil [mailto:alex.mcn...@ingenicofortronic.com] Sent: Tuesday, February 26, 2002 1:35 PM To: 'emc-p...@majordomo.ieee.org' Subject: Vehicle EMC and Safety standards Hi Group, Our financial transaction terminals are mostly used in the commercial area e.g. shops and offices, which use a separate AC/DC power supply block connected to the mains There is a requirement for these same products to be used in vehicles e.g. Taxis and Buses. These would use the power from the batteries possibly from the cigarette lighter holder (12Volts). I have obviously had to design in additional filter circuitry to account for this type of DC Supply source. My question is, will there be additional EMC and Safety requirements in Europe or North America (other than those already approved for use in commercial areas) for vehicle/mobile use? Already Approved to: EMC: EN55022 Class B, *EN55024, EN6100-3-2, EN61000-3-3, FCC Part 15, ICES-003 Safety: EN60950 (also UL/CSA) *The only additional test I can think of is for the EN55024 to include the DC Power Port tests (excluded before due to the terminal being supplied from an AC/DC power source). As usual I look forward to your invaluable replies. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.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: Vehicle EMC and Safety standards
Hi Alex, I thought that I was done looking through EMC-PSTC stuff this morning. But something popped into my head when I read your question. We made a cigarette lighter adapter for one of our products. At the time I had to look up the Automotive EMC Directive 95/54/EC. There was a website at www.rfi.co.uk which had a technical document explaining this directive. Hope this helps. Best regards. 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...@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: ESD Generator confidence test
Hi guys, Being that EMC is a side job for me. I have not been able to build an official ESD target. We calibrate our EMC test equipment (which includes an ESD gun and a multifunction transient generator EFT, Surge...) on a yearly basis. Between calibrations, I have some relatively simple methods that I use to check the equipment. For the ESD generator, I put on the air discharge tip, charge it up to 8KV and SLOWLY approach it to the ground reference plane of our setup. When the tip gets close enough to the plane, the spark jumps. After doing this many times, I've developed a feel for how far away the gun should be before the spark jumps and a feel for how the snap sounds. I know that there is all sorts of room for error here. I also feel that there is all sorts of room for error in any home-grown verification setups. Of course, if you actually go through the trouble of building the official target, use a 1GHz waveform capture scope in a Faraday cage... then you would have a verification method that is far more accurate than mine. But mine costs nothing. So my benefits/cost ratio is tough to compete with. My feeling is that the test method for ESD has more bearing on the results than equipment differences. This is where I spend my time and effort. For the EFT generator, I turn on a radio in the room. When the EFT generator is operating, the interference from the generator makes audible clicks in the music from the radio (it works for AM and FM). This saved my butt big time once. Our EFT generator had a relay failure and wasn't putting out any signal at all. There was no indication of this from the unit. However, I didn't hear interference from the radio. I immediately swapped out the DUT with an old unit that fails EFT miserablyno failure. I sent the unit back... sure enough, it was broken.If I didn't have the radio on, I would have tested eight more months worth of passing tests before I sent the unit back for cal and found out that it was broken. Again, a huge benefits/cost ratio. I have since refined this method. I now use our spectrum analyzer. It is in the same room as the EFT generator. I hook a homemade nearfield probe (a 1m length of coax with it's end cut and center conductor protruding) to the spectrum analyzer input. I then set the analyzer to a 100MHz span with a 50Mhz center frequency. When I use the EFT generator, I turn on this spectrum analyzer setup and observe the screen. The EFT generator interference from across the room produces a spectrum on the display that I am now familiar with. If I don't see this spectrum, then I know that something is up. This is still essentially free since I have the spectrum generator and near field probe anyway. One thing that I haven't figured out yet is how to easily verify the surge operation of the transient generator. (other than the brute force method below) My ultimate fallback confidence check is one of our good old LP-5000 series instruments. They were designed before the EMC directive came to be. So, they fail ESD, EFT, Surge... miserably.When in doubt, I hook one of them up. If it fails, then I at least have some confidence in my test equipment. Hey mon, got to get to work. 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...@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: Standards listing
http://europa.eu.int/comm/enterprise/newapproach/standardization/harms tds/reflist/emc.html is what you are looking for, I think. Regards Nick. At 08:34 + 26/2/2002, Richards, John wrote: Can someone please point me to a database/listing of European EMC standards? Thanks John Richards Customer Assurance Engineer Eurotherm Drives Limited --- 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
Vehicle EMC and Safety standards
Hi Group, Our financial transaction terminals are mostly used in the commercial area e.g. shops and offices, which use a separate AC/DC power supply block connected to the mains There is a requirement for these same products to be used in vehicles e.g. Taxis and Buses. These would use the power from the batteries possibly from the cigarette lighter holder (12Volts). I have obviously had to design in additional filter circuitry to account for this type of DC Supply source. My question is, will there be additional EMC and Safety requirements in Europe or North America (other than those already approved for use in commercial areas) for vehicle/mobile use? Already Approved to: EMC: EN55022 Class B, *EN55024, EN6100-3-2, EN61000-3-3, FCC Part 15, ICES-003 Safety: EN60950 (also UL/CSA) *The only additional test I can think of is for the EN55024 to include the DC Power Port tests (excluded before due to the terminal being supplied from an AC/DC power source). As usual I look forward to your invaluable replies. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax: +44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.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
Standards listing
Can someone please point me to a database/listing of European EMC standards? Thanks John Richards Customer Assurance Engineer Eurotherm Drives Limited --- 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
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 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:
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
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-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
RE: PCB floating area layout
One of the major causes of emissions can be excessive loop areas caused by a long return path for signal currents due to the division of the ground plane. Review the ground return path for signal lines that bridge the gaps. Ideally, the signal return path on the ground plane should be directly under the signal line for the entire route. Any path variation will create a loop antenna that will radiate. If you have total ground isolation, there can be a very large loop because there is no metalic return path. You will have to create a short path using high frequency bypass capacitors to bridge the gap as close as possible to the signal line. Just keep thinking about how you can reduce the loop areas. Richard Woods Sensormatic Electronics Tyco International -Original Message- From: Paolo Peruzzi [mailto:paolo.peru...@esaote.com] Sent: Monday, February 25, 2002 10:34 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
