RE: Electric strength test
The duration of test should not relate with derating of test voltage. The purpose of dielectric test is to check for any insulation breakdown. Like for production line test, it is allow to reduce the test duration to 1s, but it test at the same voltage as in 1 minute test Cheng-Wee Lai From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Miguel Abrahams Sent: Thursday, June 12, 2003 9:01 AM To: 'emc-p...@majordomo.ieee.org' Subject: Electric strength test I am looking for any technical information relating the voltage level and the applied time of the test signal in an electric strenght test. I want to find out how a dielectric test carried out at 2500Vac applied for 5 minutes compares to one carried out at 3000Vac applied for 1 minute. Thanks, Miguel Abrahams CAE 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: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc 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: emc_p...@symbol.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
Re: electric strength test
I read in !emc-pstc that Gregg Kervill gr...@test4safety.com wrote (in 002b01c25428$4985b680$7100a8c0@MENHADEN) about 'electric strength test' on Wed, 4 Sep 2002: This would suggest that it would be better to double/reinforce insulate the mains against earth, in which case SELV could be earthed. Insulation is good and can (if one is careful not to compromise its integrity - e.g. a detached wire/connector, reduced insulation) simplify the equipment construction. You almost re-invented PELV - Protected Extra-Low Voltage, IMHO a much more sensible concept than 'true SELV'. PELV is double-insulated from hazardous voltages, and earthed 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
RE: electric strength test
-Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Rich Nute Sent: Tuesday, September 03, 2002 7:31 PM To: soundsu...@aol.com Cc: Product Safety Technical Committee Subject: Re: electric strength test Hi Greg: Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? I believe (and I could be wrong) that it's a philosophy of keeping SELV intact under single fault conditions. If there's a single fault bridging mains and earth, then an SELV circuit is exposed to mains voltage unless there is basic insulation protecting it. Since it is estamited that close to 50% of the homes in the US have improperly grounded outlets, the earth connection itself is not taken into consideration as a reliable means of protection. In other words, for the purposes of the standard, an open earth connection is not considered a fault. Thanks for the explanation. One implication of this explanation is that an open earth connection is not a fault condition, but a normal condition. (Failure of basic insulation is the fault condition.) No I think not - 1) Standards are not designed on the premise that they will not be obeyed. 2) Please remember that Earth Leakage current is limited so that it will not be a hazardous source in the event of failure of Safety Earth Ground. 3) Remember also that SELV may reach an upper limit of 120Volts (for a limited time) under single fault conditions - therefore the insulation between SELV and ground must be adequate to prevent breakdown and (potential) sustained fault currents. This would suggest that it would be better to double/reinforce insulate the mains against earth, in which case SELV could be earthed. Insulation is good and can (if one is careful not to compromise its integrity - e.g. a detached wire/connector, reduced insulation) simplify the equipment construction. Please refer to Conformity August Show Issue p 38. --- 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: electric strength test
Hi Greg: Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? I believe (and I could be wrong) that it's a philosophy of keeping SELV intact under single fault conditions. If there's a single fault bridging mains and earth, then an SELV circuit is exposed to mains voltage unless there is basic insulation protecting it. Since it is estamited that close to 50% of the homes in the US have improperly grounded outlets, the earth connection itself is not taken into consideration as a reliable means of protection. In other words, for the purposes of the standard, an open earth connection is not considered a fault. Thanks for the explanation. One implication of this explanation is that an open earth connection is not a fault condition, but a normal condition. (Failure of basic insulation is the fault condition.) This would suggest that it would be better to double/reinforce insulate the mains against earth, in which case SELV could be earthed. (This also solves the problem of accessible earthed parts becoming live when used on a system with no earthing connection.) But, unfortunately, the requirement remains that true SELV cannot be connected to earth, and must have basic insulation between it and earth. 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...@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: electric strength test
On Sat, 24 Aug 2002 12:43:43 EDT, soundsu...@aol.com wrote: Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? I believe (and I could be wrong) that it's a philosophy of keeping SELV intact under single fault conditions. If there's a single fault bridging mains and earth, then an SELV circuit is exposed to mains voltage unless there is basic insulation protecting it. Since it is estamited that close to 50% of the homes in the US have improperly grounded outlets, the earth connection itself is not taken into consideration as a reliable means of protection. In other words, for the purposes of the standard, an open earth connection is not considered a fault. In such situation, I think touching the earthed enclosure can cause electric shock anyway, and insulating SELV circuit from the earth may not help much. What I guess is: if a SELV circuit is earthed, touching the other point of the SELV circuit will close the loop and the SELV circuit can draw current through the human body - I think (only a guess and I could be wrong) the committee might want to avoid such situation by requring basic insulation. Regards, Tom -- Tomonori Sato vef00...@nifty.ne.jp URL: http://member.nifty.ne.jp/tsato/ --- 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: electric strength test
In a message dated 8/24/02 2:08:10 AM Eastern Daylight Time, j...@jmwa.demon.co.uk writes: Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? I believe (and I could be wrong) that it's a philosophy of keeping SELV intact under single fault conditions. If there's a single fault bridging mains and earth, then an SELV circuit is exposed to mains voltage unless there is basic insulation protecting it. Since it is estamited that close to 50% of the homes in the US have improperly grounded outlets, the earth connection itself is not taken into consideration as a reliable means of protection. In other words, for the purposes of the standard, an open earth connection is not considered a fault. Greg Galluccio www.productapprovals.com A HREF=www.soundsurfr.comwww.soundsurfr.com/A A HREF=www.artistlaunch.com/soundsurfrSoundsurfr At ArtistLaunch/A A HREF=http://www.artistlaunch.com/twominds;Two Minds At Artistlaunch/A A HREF=http://www.mp3.com/soundsurfr;Soundsurfr At MP3.com/A
Re: electric strength test
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200208232012.naa27...@epgc264.sdd.hp.com) about 'electric strength test' on Fri, 23 Aug 2002: Hi John: True SELV . requires double or reinforced insulation from hazardous live parts/parts at hazardous voltages [different expressions used for the same things] and basic insulation from earth. '950 SELV' allows SELV circuits to be earthed (see 2.2.3.3 of IEC60950:1999 or EN60950:2000 or of IEC/EN 60950-1). Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? This is a question that has bothered me for a number of years. [AOL] Me too [/aol] You would have to ask the people who originated SELV. -- 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: electric strength test
Hi John: True SELV . requires double or reinforced insulation from hazardous live parts/parts at hazardous voltages [different expressions used for the same things] and basic insulation from earth. '950 SELV' allows SELV circuits to be earthed (see 2.2.3.3 of IEC60950:1999 or EN60950:2000 or of IEC/EN 60950-1). Why does True SELV require basic insulation between SELV and earth? What is the hazardous voltage source, and what is the current path through the body if that basic insulation should fail? This is a question that has bothered me for a number of years. Thanks, and 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...@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: electric strength test
Group, In Annex ZB to EN 60950:2000, under Clause 1.7.2, Norway has a marking requirement for Class I, Type A pluggable equipment (intended for connection of other equipment) where the safety relies on the connection to protective earth. The marking must state that the equipment is required to be connected to an earthed mains socket-outlet. Sweden has a similar marking requirement under the same clause. If my interpretation is correct, a manufacturer can ship Class 1 ITE products into Norway with only basic insulation from primary to earth ground with this marking, and that they would need to rely on the customer to properly ground the outlets at the installation site. Is this a valid assumption for equipment intended to be installed in telecom locations? What is not clear to me also , is whether these markings can be provided in the installation manual or if it is required to be marked on the equipment. Regards, Richard A Meyette, PE meye...@pacbell.net At 09:37 PM 8/22/02 +0100, you wrote: I read in !emc-pstc that Tyra, John john_t...@bose.com wrote (in 418fbd441c22d5118d860003470d43160543e...@cupid.bose.com) about 'electric strength test' on Thu, 22 Aug 2002: If you plan on selling in this region you should check all of the National deviations and maybe contact DEMKO (part of UL now) to see if this is still required for the Nordic countries It applies only to Norway. -- 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 --- 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: electric strength test
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200208222310.qaa20...@epgc264.sdd.hp.com) about 'electric strength test' on Thu, 22 Aug 2002: That depends on which variety of SELV you mean. True SELV, as opposed to '950 SELV', requires double or reinforced insulation from earth Why? 'No reason, it's company policy.' Seriously, though, what I wrote is not correct. I originally wrote a much longer sentence that I then tried to cut down and in doing so, preserved unmatched pieces. True SELV . requires double or reinforced insulation from hazardous live parts/parts at hazardous voltages [different expressions used for the same things] and basic insulation from earth. '950 SELV' allows SELV circuits to be earthed (see 2.2.3.3 of IEC60950:1999 or EN60950:2000 or of IEC/EN 60950-1). -- 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: electric strength test
On Thu, 22 Aug 2002 21:42:34 +0100, John Woodgate j...@jmwa.demon.co.uk wrote: Pri to true SELV secondary doesn't pose a problem. The chassis is irrelevant. For '950 SELV', there is no requirement for a pri-sec test at any voltage above that for pri-chassis. Really? I thought primary - earthed chassis (Brian didn't said that the chassis is earthed, but I guess so) can have basic insulation, but primary - SELV should have double or reinforced insulation unless it is protected with other method such as earthed screen or protective bonding. On Thu, 22 Aug 2002 06:57:25 -0700, Brian O'Connell boconn...@t-yuden.com wrote: to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. The clause said that components which are NOT INVOLVED in the test may be disconnected, but it seems the Y-caps ARE involved in the test. Isn't it? Regards, Tom -- Tomonori Sato vef00...@nifty.ne.jp URL: http://member.nifty.ne.jp/tsato/ --- 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: electric strength test
Hi John: That depends on which variety of SELV you mean. True SELV, as opposed to '950 SELV', requires double or reinforced insulation from earth Why? 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...@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: electric strength test
Hi John: Y-caps have enough margin to easily withstand the 4300 V dc without damage. Without immediate failure, no doubt. But such a huge overstress may cause latent damage that later results in failure, and, since IEC 60384 doesn't call for such an over-voltage test, the failure might not be a fail-safe failure. According to my copy of 384 (1996), a Y1 cap is proof-tested at 4000 V ac. 4300 V dc should not be a problem. However, a Y2 cap is proof-tested at 1500 V ac, and this might be a problem just as you suggest. Note that I suggested this overvoltage not as a production test, but as a type test during product evaluation -- to learn the weakest point in the insulation system. If the cap should fail, then you know that the cap is the weakest part. I then remove the cap, and repeat the test to determine the next weakest link. Knowing the weakest link in an insulation system can be quite valuable when a production problem arises. 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...@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: electric strength test
Hi Brian: What I've always wondered about, at least for class 1 construction, is just what is really being tested by the pri/sec hi-pot, when the customer chooses to ground the power supply's return. (These comments presume the secondary is SELV.) When you use a ground for safety purposes, the ground circuit must be capable of carrying the fault current. (This construction is called bonding.) Typically, the construction of the secondary ground circuit does not meet the requirements of bonding. Consequently, the ground cannot be relied upon for safety. Therefore, pri-sec insulation must be double/ reinforced. So, the pri-gnd insulation is basic and is backed up by grounded/bonded parts. And, the pri-sec insulation is basic backed up by supplementary (or is reinforced). (Most switching-mode transformers don't use a grounded shield between pri-sec as this reduces coupling and does other things that reduce the effectiveness of the transformer. Therefore most switching-mode transformers use double or reinforced insulation between pri-sec.) By the way, another reason for not using the secondary ground for safety is that the sec winding may not be capable of carrying the fault current, and will open. The problem is that fault current is passing through the part of the winding that is grounded, that part of the winding opens, and the high side of the SELV secondary is now connected to primary. Also,as some of our output-to-chassis Y caps are just 100V decouple caps, and because SELV to P.E. spacing and insulation requirements would never withstand reinforced test levels, how does the end-use installation ever get pri/sec hi-pot to pass without removing the unit from the chassis? There is no requirement for SELV-to-PE spacings and insulation. After all, both the SELV and the PE are accessible parts and need not have any safety insulation or spacings between them. If your SELV is floating, then the pri-sec hi-pot test is simply pri-sec. No connection to chassis or ground. This will, however, damage your sec decoupling caps because there will be a capacitive voltage divider from primary to Y-cap to chassis to decoupler cap to sec. To prevent overvoltage of the decoupler, either short it out or open it. 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...@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: electric strength test
I read in !emc-pstc that Brian O'Connell boconn...@t-yuden.com wrote (in f7e9180f6f7f5840858d3db815e4f7ad1f2...@cms21.t-yuden.com) about 'electric strength test' on Thu, 22 Aug 2002: Also,as some of our output-to-chassis Y caps are just 100V decouple caps, Y-caps are specifically for connection between mains conductors and earth/ground. No others should be called 'Y-caps'. and because SELV to P.E. spacing and insulation requirements would never withstand reinforced test levels, That depends on which variety of SELV you mean. True SELV, as opposed to '950 SELV', requires double or reinforced insulation from earth how does the end-use installation ever get pri/sec hi-pot to pass without removing the unit from the chassis? Pri to true SELV secondary doesn't pose a problem. The chassis is irrelevant. For '950 SELV', there is no requirement for a pri-sec test at any voltage above that for pri-chassis. -- 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: electric strength test
I read in !emc-pstc that Tyra, John john_t...@bose.com wrote (in 418fbd441c22d5118d860003470d43160543e...@cupid.bose.com) about 'electric strength test' on Thu, 22 Aug 2002: If you plan on selling in this region you should check all of the National deviations and maybe contact DEMKO (part of UL now) to see if this is still required for the Nordic countries It applies only to Norway. -- 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: electric strength test
I read in !emc-pstc that Peter Merguerian pmerguer...@itl.co.il wrote (in 2D1037012914D4118DB8204C4F4F50203DD9CC@ITLLTD01) about 'electric strength test' on Thu, 22 Aug 2002: You may come across some distributors in Norway asking for DI or RI between PRI-EARTH, even for Class 1 power supplies. That's because Norway uses the 'IT' power distribution system, where neither mains conductor is earthed directly, but one is earthed through a quite high impedance to prevent common-mode charge build-up. -- 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: electric strength test
I read in !emc-pstc that Rich Nute ri...@sdd.hp.com wrote (in 200208221745.kaa19...@epgc264.sdd.hp.com) about 'electric strength test' on Thu, 22 Aug 2002: Y-caps have enough margin to easily withstand the 4300 V dc without damage. Without immediate failure, no doubt. But such a huge overstress may cause latent damage that later results in failure, and, since IEC 60384 doesn't call for such an over-voltage test, the failure might not be a fail-safe failure. -- 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: electric strength test
Brian - From what I can glean from your message, the equipment is Class 1, but the secondaries do not rely on earthing for SELV reliability (hence, the Reinforced Insulation EST value). However, there appears to be some functional earthing of secondary circuits or there would be no problems for your Y caps. If the above is true, the Y caps must provide Reinforced insulation. Alternatively, there are allowances for two Y caps in series you might be able to exploit (see 1.5.7.1). If the above is not true, in that earthing of secondary circuits is necessary to maintain compliance with SELV requirements, you should not need to perform an EST at Reinforced values. Basic Insulation will do, eliminating issue for the Y caps. Irrespective of these alternatives, the implication of only needing Basic Insulation for the Y cap and Reinforced Insulation for the purposes of your primary to secondary EST is that you should be able to completely disconnect the Y cap and leave it dangling, without connecting the Y cap at all. Challenge the test house engineer for a solid engineering rationale. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com -Original Message- From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Brian O'Connell Sent: Thursday, August 22, 2002 6:57 AM To: emc-p...@majordomo.ieee.org Subject: electric strength test Good People of PSTC: I am attempting to comply with both the letter and spirit of 60950:2000, cl 5.2. Note that 5.2.2 allows for separate testing, according the type of insulation required. When testing a (class 1) power supply, the withstand level for primary to chassis is Basic; and for primary to secondary is Reinforced. Typically, I will apply approx 2500vdc for Basic and 4300vdc for reinforced. But to pass primary to secondary test, 60950 says that I can allow for following: care is taken that the voltage applied to the reinforced insulation does not overstress basic Also to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, unless I physically remove all Y-caps (and the unit will not operate reliably with y-caps). I have inspected units from several other companies and have determined that it was not possible to have ever passed pri-sec test levels without isolating these circuits. What test technique generally accepted by your agency engineers? TIA. R/S, Brian O'Connell Taiyo Yuden (USA), 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...@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: electric strength test
Some very useful replies from all. What I've always wondered about, at least for class 1 construction, is just what is really being tested by the pri/sec hi-pot, when the customer chooses to ground the power supply's return. Also,as some of our output-to-chassis Y caps are just 100V decouple caps, and because SELV to P.E. spacing and insulation requirements would never withstand reinforced test levels, how does the end-use installation ever get pri/sec hi-pot to pass without removing the unit from the chassis? R/S, Brian -Original Message- From: Tyra, John [mailto:john_t...@bose.com] Sent: Thursday, August 22, 2002 12:02 PM To: 'Peter Merguerian'; 'Brian O'Connell'; emc-p...@majordomo.ieee.org Subject: RE: electric strength test I agree with Peter, per the standard, and most IEC product standards, you need two levels of protection from electric shock. In your case the y-caps provide one level (basic insulation) and the earth connection provides the second. As long as your earth path, between primary and secondary (I am assuming your secondary is connected or coupled to earth), will pass the Earth continuity test then it is unreasonable for the agency engineer to enforce reinforced dielectric requirements on the basic insulation Y-caps and you should be allowed to lift them during the test. You need to politely ask him to check with his superior on this one! I have not worked with 950 in many years now but I do remember that the Nordic agencies were requiring reinforced spacing and insulation between primary and earth for the reasons Peter cited. If you plan on selling in this region you should check all of the National deviations and maybe contact DEMKO (part of UL now) to see if this is still required for the Nordic countries -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Thursday, August 22, 2002 1:09 PM To: 'Brian O'Connell'; emc-p...@majordomo.ieee.org Subject: RE: electric strength test Brian, Your interpretation of the standard and application of the test between pri-sec is acceptable. You need to speak to a higher level person in the agency who is an expert! Please be advised that some countries do not have a reliable earthing system. Many end-product manufacturers design their equipment such that the power supply has double insulation or reinforced insulation between pri-earth. Norway is a good example. You may come across some distributors in Norway asking for DI or RI between pri-sec, even for Class 1 power supplies. Good luck at the agency! 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: Brian O'Connell [mailto:boconn...@t-yuden.com] Sent: Thursday, August 22, 2002 3:57 PM To: emc-p...@majordomo.ieee.org Subject: electric strength test --- 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: electric strength test
I agree with Peter, per the standard, and most IEC product standards, you need two levels of protection from electric shock. In your case the y-caps provide one level (basic insulation) and the earth connection provides the second. As long as your earth path, between primary and secondary (I am assuming your secondary is connected or coupled to earth), will pass the Earth continuity test then it is unreasonable for the agency engineer to enforce reinforced dielectric requirements on the basic insulation Y-caps and you should be allowed to lift them during the test. You need to politely ask him to check with his superior on this one! I have not worked with 950 in many years now but I do remember that the Nordic agencies were requiring reinforced spacing and insulation between primary and earth for the reasons Peter cited. If you plan on selling in this region you should check all of the National deviations and maybe contact DEMKO (part of UL now) to see if this is still required for the Nordic countries -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Thursday, August 22, 2002 1:09 PM To: 'Brian O'Connell'; emc-p...@majordomo.ieee.org Subject: RE: electric strength test Brian, Your interpretation of the standard and application of the test between pri-sec is acceptable. You need to speak to a higher level person in the agency who is an expert! Please be advised that some countries do not have a reliable earthing system. Many end-product manufacturers design their equipment such that the power supply has double insulation or reinforced insulation between pri-earth. Norway is a good example. You may come across some distributors in Norway asking for DI or RI between pri-sec, even for Class 1 power supplies. Good luck at the agency! 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: Brian O'Connell [mailto:boconn...@t-yuden.com] Sent: Thursday, August 22, 2002 3:57 PM To: emc-p...@majordomo.ieee.org Subject: electric strength test Good People of PSTC: I am attempting to comply with both the letter and spirit of 60950:2000, cl 5.2. Note that 5.2.2 allows for separate testing, according the type of insulation required. When testing a (class 1) power supply, the withstand level for primary to chassis is Basic; and for primary to secondary is Reinforced. Typically, I will apply approx 2500vdc for Basic and 4300vdc for reinforced. But to pass primary to secondary test, 60950 says that I can allow for following: care is taken that the voltage applied to the reinforced insulation does not overstress basic Also to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, unless I physically remove all Y-caps (and the unit will not operate reliably with y-caps). I have inspected units from several other companies and have determined that it was not possible to have ever passed pri-sec test levels without isolating these circuits. What test technique generally accepted by your agency engineers? TIA. R/S, Brian O'Connell Taiyo Yuden (USA), 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...@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
RE: electric strength test
Brian, Correction: You may come across some distributors in Norway asking for DI or RI between PRI-EARTH, even for Class 1 power supplies. -Original Message- From: Peter Merguerian To: 'Brian O'Connell'; emc-p...@majordomo.ieee.org Sent: 8/22/02 7:09 PM Subject: RE: electric strength test Brian, Your interpretation of the standard and application of the test between pri-sec is acceptable. You need to speak to a higher level person in the agency who is an expert! Please be advised that some countries do not have a reliable earthing system. Many end-product manufacturers design their equipment such that the power supply has double insulation or reinforced insulation between pri-earth. Norway is a good example. You may come across some distributors in Norway asking for DI or RI between pri-sec, even for Class 1 power supplies. Good luck at the agency! 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: Brian O'Connell [mailto:boconn...@t-yuden.com] Sent: Thursday, August 22, 2002 3:57 PM To: emc-p...@majordomo.ieee.org Subject: electric strength test Good People of PSTC: I am attempting to comply with both the letter and spirit of 60950:2000, cl 5.2. Note that 5.2.2 allows for separate testing, according the type of insulation required. When testing a (class 1) power supply, the withstand level for primary to chassis is Basic; and for primary to secondary is Reinforced. Typically, I will apply approx 2500vdc for Basic and 4300vdc for reinforced. But to pass primary to secondary test, 60950 says that I can allow for following: care is taken that the voltage applied to the reinforced insulation does not overstress basic Also to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, unless I physically remove all Y-caps (and the unit will not operate reliably with y-caps). I have inspected units from several other companies and have determined that it was not possible to have ever passed pri-sec test levels without isolating these circuits. What test technique generally accepted by your agency engineers? TIA. R/S, Brian O'Connell Taiyo Yuden (USA), 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...@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
Re: electric strength test
Hi Brian: I am attempting to comply with both the letter and spirit of 60950:2000, cl 5.2. Note that 5.2.2 allows for separate testing, according the type of insulation required. When testing a (class 1) power supply, the withstand level for primary to chassis is Basic; and for primary to secondary is Reinforced. Typically, I will apply approx 2500vdc for Basic and 4300vdc for reinforced. But to pass primary to secondary test, 60950 says that I can allow for following: care is taken that the voltage applied to the reinforced insulation does not overstress basic Good requirement and good advice. But, very difficult to apply in practice. Also to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. Again, good advice but very difficult to apply in practice. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. Well... I would just lift the cap and let it hang in air for the test. Inserting solid insulation between the Y-cap terminal and the chassis means that you must also consider: the creepage and clearance around the solid insulation, and that most of the hi-pot voltage will appear across the solid insulation. A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, unless I physically remove all Y-caps (and the unit will not operate reliably with y-caps). I have inspected units from several other companies and have determined that it was not possible to have ever passed pri-sec test levels without isolating these circuits. Inserting the solid insulator DOES NOT defeat the purpose of the test. While it is true that the inserted solid insulation gets tested in parallel with the pri-sec reinforced insulation, the test results apply to the pri-sec insulation. If a failure should occur, then it would be necessary to sort out whether the failure was your inserted solid insulation or the pri-sec insulation. If your secondary is not grounded, then you can open the protective ground and test pri-sec without lifting the Y-cap. (Put the unit on an insulating surface, and be careful not to touch the unit during this test!) Our products are designed in the same way. We don't lift the Y-caps or anything else when we hi-pot pri-sec (secondary is functionally grounded). Y-caps have enough margin to easily withstand the 4300 V dc without damage. In other words, our pri-gnd meets 4300 V dc. In general, solid insulations have electric strengths in the neighborhood of 10 kV or more. The required spacings have electric strengths in the neighborhood of 5 kV. Y-cap electric strength usually is greater than the lead spacing. You should expect a system electric strength approaching 5 kV rms. During design, we always hi-pot test to failure or max voltage of the hi-pot tester, whichever is lower. In our designs, the weakest point (4500-5000 V rms) in the power supply is the pwb terminals of the Y-cap on the back side of the board (where the sharp points are located). The hi-pot test is a pass-fail test, and gives no data. Hi-pot to failure identifies and measures the weakest link. This is useful data for future evaluation of production-line hi-pot failures. Good luck, and 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...@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: electric strength test
Brian, Your interpretation of the standard and application of the test between pri-sec is acceptable. You need to speak to a higher level person in the agency who is an expert! Please be advised that some countries do not have a reliable earthing system. Many end-product manufacturers design their equipment such that the power supply has double insulation or reinforced insulation between pri-earth. Norway is a good example. You may come across some distributors in Norway asking for DI or RI between pri-sec, even for Class 1 power supplies. Good luck at the agency! 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: Brian O'Connell [mailto:boconn...@t-yuden.com] Sent: Thursday, August 22, 2002 3:57 PM To: emc-p...@majordomo.ieee.org Subject: electric strength test Good People of PSTC: I am attempting to comply with both the letter and spirit of 60950:2000, cl 5.2. Note that 5.2.2 allows for separate testing, according the type of insulation required. When testing a (class 1) power supply, the withstand level for primary to chassis is Basic; and for primary to secondary is Reinforced. Typically, I will apply approx 2500vdc for Basic and 4300vdc for reinforced. But to pass primary to secondary test, 60950 says that I can allow for following: care is taken that the voltage applied to the reinforced insulation does not overstress basic Also to avoid damage to components or insulation which are not involved in the test, disconnection of ICs or the like and the use of equipotential bonding are permitted. For Pri/Sec testing, the screw connecting the Y-caps to the chassis is removed, insulation is inserted between the screw insert and chassis. A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, unless I physically remove all Y-caps (and the unit will not operate reliably with y-caps). I have inspected units from several other companies and have determined that it was not possible to have ever passed pri-sec test levels without isolating these circuits. What test technique generally accepted by your agency engineers? TIA. R/S, Brian O'Connell Taiyo Yuden (USA), 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...@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: electric strength test
I read in !emc-pstc that Brian O'Connell boconn...@t-yuden.com wrote (in f7e9180f6f7f5840858d3db815e4f7ad1f2...@cms21.t-yuden.com) about 'electric strength test' on Thu, 22 Aug 2002: A (new) agency engineer says that inserting a piece of insulator defeats the purpose of the test. I don't see how. For class 1 construction, it is just not possible for me to pass 4300vdc test levels without inserting my little piece of valox, You need 4300 V only if the secondary circuits are SELV and thus isolated from the chassis. But this is very unusual. I suppose you could use two supplies, +2500 V from primary to chassis and -1800 V from secondary to chassis, but I've never heard of anyone doing that. An earthed screen between the primary and secondary windings in the transformer would overcome the problem another way. -- 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
