Re: Green/Yellow Earthing Leads
I read in !emc-pstc that Peter Merguerian pmerguer...@itl.co.il wrote (in 2D1037012914D4118DB8204C4F4F50203DDA3E@ITLLTD01) about 'Green/Yellow Earthing Leads' on Mon, 2 Sep 2002: BTW IEC 60 204 standard for electrical equipment for machinery states the bicolour combination GREEN-AND-YELOW shall be such that on any 15mm length one of the colours covers at least 30% and not more than 70% of the surface of the conductor, tje other colour covering the remainder of the surface. That is the specification that appears also in other IEC standards, and in many other standards for cables as well. -- 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...@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
Green/Yellow Earthing Leads
Dear Group, What is the percentage of color over a surface area for the insulated green/yellow earthing conductor. Is it better to have more yellow than green or more green than yellow. I know North Americans prefer more green than yellow and Europeans like more yellow than green. Any historical reason? I hope it has nothing to do with the Boston Tea Party! Can the group we come up with some compromise? BTW IEC 60 204 standard for electrical equipment for machinery states the bicolour combination GREEN-AND-YELOW shall be such that on any 15mm length one of the colours covers at least 30% and not more than 70% of the surface of the conductor, tje other colour covering the remainder of the surface. 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
RE: Telephone headsets
Chris, In your subject and ending you specify telephone headsets; in the body of your message you specify connection to audio amplifiers. For telephone headsets: use EN 60 950 and the RTTE Directive. Note the limit of 50 Vac/75 Vdc is not applicable under the RTTE Directive. There is really not much to comply with under EN 60 950 except for the flammability fo materials - the standard does not yet address acoustic requirements as in the UL60950 requirements. For audio/video equipment: use EN 60065 however, the LVD does not apply because of the 50 Vac/75 Vdc cutofff as mentioned in your e-mail. In this case, you may wish to consider complying with the EMC Directive and just make a declaration based on engineering judgement. 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: Chris K. Poore [mailto:chr...@percept.com] Sent: Friday, August 30, 2002 4:02 PM To: EMC-PSTC Subject: Telephone headsets We have some telephone headsets that we want to CE Mark, but are not sure what safety standard to use. Additionally, I don't see any category under the CE Marking directive that would be entirely applicable. The LVD seems most logical, except that the input voltage to the headsets is well below the 75DC, 50AC cutoff. The headsets will connect to an OEM audio amplifier that has been evaluated to the LVD, and seems to contain all the necessary isolation (we are not even selling the amplifier). The primary reason for wanting to CE Mark is because a competitor is doing it. Is there a safety standard that we should use that is specific to these telephone headsets for EU compliance? Thanks, Chris K. Poore Staff Compliance Engineer - Percept Technology Labs, Inc. 4735 Walnut #E Boulder, CO 80301 303-444-7480 ext. 113 303-444-1565 Fax mailto:chr...@percept.com http://www.percept.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: Designing for low power conducted and radiated immunity - Thanx
I read in !emc-pstc that Chris Chileshe chris.chile...@ultronics.com wrote (in 01c25266.1d499aa0.chris.chile...@ultronics.com) about 'Designing for low power conducted and radiated immunity - Thanx' on Mon, 2 Sep 2002: I believe the gist of your responses was that it is a bit of a tall order to try and get a filter that will let 25kHz signals through and reject RF at 150kHz. No problem if the 25 kHz signals were sine waves. It's the harmonics in the digital/pulse signals that make it difficult. If you put in a filter (with a reasonably good phase response) at, say, 30 kHz, and then amplified and hard-clipped the 25 kHz signals, you might be OK. -- 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...@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: Designing for low power conducted and radiated immunity - Thanx
Hi group, Thank you everyone for your great responses on the subject. Sorry I couldn't acknowledge your postings earlier than this and sorry I haven't acknowledged your postings individually. Had to go away somewhere - at short notice. Only just returned. I believe the gist of your responses was that it is a bit of a tall order to try and get a filter that will let 25kHz signals through and reject RF at 150kHz. To this end, I am thinking I may have to design a separate filter circuit for the output while keeping my original filter strategies on the DC lines. Any fundamental flaws in this reasoning? Gert and others raise a few points I would like to comment/pursue/query etc. Note that I have to assume screened cable is not an option initially and further that the output it is a PWM square wave with a maximum fundamental frequency of 25kHz and not 25kbit.. 2/ It has not been proved that the sensor actually degrades when exposed to the signals. My fault. I didn't supply you with enough information. I have the analog version of the sensor. Before addition of the pi-filters it was very susceptible. With only LC filtering, it was much better but still showed mild susceptibility during conducted immunity tests although the radiated immunity was vastly improved. With PI filters, it was immune over the full test spectrum 150k-1G. 3/ A CM coil may be applied with a asym signal if certain conditions are met (esp. grounding ) I have had bad experiences with trying to use CM chokes on asym. lines, but you make a point about grounding, so maybe worth another look? 5/ standard EMI filters of the pi-type will probably do the job. I recommend using off the shelve parts available easily. I have heard conflicting reports on these devices. I have heard from certain 'well-informed' sources that the SMT PI-filters which one can get from the big manufacturers do not work quite as well as filters made from discrete SM devices. Any experiences worth sharing - anyone? Is it all about 'horses for courses' i.e. the right filters for the job. 7/ The value of reasonable impedance does not need to be that high 300- 500 Ohms is sufficient. Don't over do. That is a good point. I work to a minimum of 300 Ohms - and where I have to squeeze every last bit of the spectrum into the useable range on a ferrite, will accept slightly lower (usually means using larger caps-to-case to maintain the impedance ratio). Thank you again for the wonderful responses. - Best regards - Chris Chileshe - Ultronics Ltd -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Chris Chileshe Sent: Thursday, August 22, 2002 11:31 AM To: 'emc-pstc' Subject: Designing for low power conducted and radiated immunity Dear all, On the evidence of the quality of responses I have seen on more difficult queries, I think this should be fairly straightforward for all you RF engineers out there. My product is a small 3-wire pressure sensor which sends out a digital bit stream encryption of the pressure measured. It's current draw is around 30mA max. The bit stream is around 25kHz, 5V TTL. The 3-wires are simply supply (5-10VDC), Output (5V logic) and Ground. I am trying to make the product pass conducted RF immunity tests to EN 61000-4-6 (150kHz - 80Mhz) at 10V and radiated immunity tests to EN 61000-4-3 (80Mhz - 1Ghz) at 30V/m. There is an intrinsic safety limit on the overall capacitance I can use in the product. My general thoughts are to use a PI-filter on each of the 3 lines with the vertical section of the filter being ceramic capacitors to the metal case enclosure. A limit of about 10nF exists (for other reasons) on these capacitors. The horizontal section of the PI will be made up of a series connection of a ferrite (for high frequency suppression) and an inductor for the lower frequencies where the ferrite is transparent - in that order. My problems (sorry .. challenges) are as follows: 1 - I need to let a bit stream through at 25kHz, but reject RF at 150kHz without a common mode choke (output is not differential). Is this a tall order? 2 - The inductors that give me a reasonable value of impedance at these sub 1Mhz frequencies tend to be largish and have Self Resonant Freqs. in the test spectrum albeit some of them (SRFs) are in the radiated immunity band where I expect the ferrite to be in charge of attenuation. Is this likely to cause me problems? 3 - Can I find a single ferrite that will cover the entire RF test spectrum of EN 61000-6-2 ( 150kHz - 1Ghz) or is it generally accepted that even the so called 'wideband' ferrites (SMT 0603/0805 max) are good down to about 5MHz but no lower? Any relevant comments welcome. Best regards - Chris Chileshe - Ultronics Ltd This e-mail has been scanned for all viruses by Star Internet.