Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
In message 63056535adcf774b87d41a999d9a7f2b23732...@bct1e2k301.americas.tsp.ad, dated Tue, 21 Dec 2010, Goedderz, Jim jgoedd...@tycoint.com writes: Is there any additional response to Pat's inquiry? I would also like to know the justification of a VDR/gas discharge tube connection in the primary circuit. It would be useful to have that available. Some information became available very recently. This is not a standard or even an official interpretation of a standard. I suppose it is advice having a strong provenance: TC108 position on varistors having connection to the mains, also identified as voltage dependent resistors (VDR) and metal oxide varistors (MOV). During the recent TC108 meetings in Seattle, October 2010, the use of varistors having connection to mains circuits was discussed. There seemed to be different opinions and interpretations regarding the requirements contained in several of the TC108 standards. This INF document is intended to clarify the current interpretation of TC108 on those aspects where agreement has been reached. Some issues are still under discussion and these will be explained as soon as possible. Existing requirements not addressed below remain applicable. The following statements are supported by the experts and the management of TC108 on the application of varistors in the IEC 60065, IEC 60950-1 and IEC 62368-1 standards. -- Compliance with IEC 61051-2 Where a varistor is used in connection with the mains, it shall comply with IEC 61051-2. The combination pulse test of IEC 61051-2:1991, Am 1:2009 (2.3.6, Table I group 1 and Annex A), including consideration of the nominal mains voltage and overvoltage category, should be allowed as an alternative to the requirements in the current standards. Protection of varistors Where a varistor is used in parallel with the mains connection, it should be protected against temporary overvoltages, overloads or short circuits. Details can be found in IEC 60950-1, clause 1.5.9.2. Varistors in series with a GDT (for all types of equipment, including 'normal' Pluggable Type A equipment) Where a varistor in series with a GDT is used to bridge BASIC INSULATION, the following applies: – the varistor has to comply with IEC 61051-2 as indicated in the standards; and – the GDT has to comply with: • the electric strength test for BASIC INSULATION; and • the external CLEARANCE and CREEPAGE DISTANCE requirements for BASIC INSULATION. It should be noted that the use of a VDR in series with a GDT to bridge reinforced insulation was also discussed. So far, no agreement was reached within IEC TC108. -- It should be noted that each of the mentioned standards is currently being revised under the TC 108 maintenance procedures and these clarifications will be introduced in the relevant standards as deemed necessary. -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK Plural: data, criteria. Singular: datum (different meaning: use 'data element' for a single item), criterion. 'Effect' is a noun, 'affect' is a verb (except in psychiatry). - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Is there any additional response to Pat's inquiry? I would also like to know the justification of a VDR/gas discharge tube connection in the primary circuit. It would be useful to have that available. James Goedderz Sr. Principal Engineer-Product Safety Sensormatic Electronics, LLC 561.912.6378 -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of pat.law...@slpower.com Sent: Wednesday, December 15, 2010 9:05 PM To: emc-p...@ieee.org Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. I found this in UL 60950, clause 1.5.9.1: -- quote --- If a surge suppressor is used in a PRIMARY CIRCUIT, it shall be a VDR and it shall comply with Annex Q. NOTE 1 A VDR is sometimes referred to as a varistor or a metal oxide varistor (MOV). Devices such as gas discharge tubes, carbon blocks and semiconductor devices with non-linear voltage/current characteristics are not considered as VDRs in this standard. --- end quote --- This sounds like it prevents the use of VDR/gas discharge tube combinations to limit primary-to-earth line surges, or gas discharge tubes in the primary completely. Is this correct? I'll bet the gas tube companies are having heartburn over this. Pat Lawler EMC Engineer SL Power Electronics Corp. ri...@ieee.org wrote on 12/15/2010 12:05:18 PM: On 12/15/2010 11:41, Kunde, Brian wrote: Does it make VDRs safer to use them in series with a gas-tube like some do with Varistors? Hi Brian: Yes. Today, this is the trend among manufacturers that want to use a VDR between mains and earth. And, TC108 is still trying to sort out the requirements for both devices in such a circuit. Best wishes for a Merry Christmas, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
As I previously mentioned, the hi-pot test is for SOLID insulation. Presumably, the insulation between the side panels and the mains circuits is air, or air in series with solid insulation. So, it should be valid to test without the side panels. Merry Christmas! Rich On 12/16/2010 06:16, Kunde, Brian wrote: Here is another clunky suggestion. What if you put your Surge Suppressor circuit after a dual pole circuit breaker that is only energized when the device is powered up. That way, the VDR is out of the circuit during the Hipot test, but in-circuit during the Surge Immunity test. This brings up a good point in regards to production hipot testing. Some of our instruments have double pole relays, so during hipot those downstream circuits do not get tested. So those circuits have to be individually hipot tested before the side panels are installed. As you said, this goes against the intent of the production hipot test, but what else can you do? You do the best you can. If an inspector disagrees, have him give you the solution. The Other Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: OT A BIT........ [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
David, You have to ask yourself, what would secondary protection be protecting? As part of your Risk Assessment or circuit Fault Analysis, you must consider what would happen if the VDR/MOV faulted in a high current or short circuit condition. If the high current can cause overheating in wiring, traces, connectors, components, etc. which could cause a fire, then yes, some kind of additional protection device must be added. If not, the answer is no. I hate it when I'm told by safety people that you must do this or do that without consideration of the specific design. For example, most power supplies (PSU) have a Line to Line VDR/MOV, but it is after the onboard fuse provided to protect the entire PSU. If the VDR/MOV faulted, the fuse would open. So an additional protection device for the VDR/MOV would not be needed. If you do need to add protection for your VDRs, make it robust enough so it does not open after your first thunderstorm. The Other Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Spencer, David H Sent: Wednesday, December 15, 2010 7:12 PM To: Bill Owsley; EMC-PSTC@LISTSERV.IEEE.ORG; oconne...@tamuracorp.com Subject: RE: OT A BIT [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. My safety people are telling me that part of Ed. 2 also requires that VDR's line to line ( or line to neutral) have secondary protection. Either a fuse, gas tube, or double insulated cap.They have been with great gusto been pulling out the VDR's or replacing them with fused versions. From an EMC aspect, we never know when a VDR (from now on MOV) goes bad. SO with respect to line to line (neutral) MOV's only and Ed.2 Do MOV's need a secondary protection? thanks for any comments Regards David Spencer EHS EMC Engineer Xerox Corp -Original Message- From: emc-p...@ieee.org on behalf of Bill Owsley Sent: Wed 12/15/2010 3:57 PM To: EMC-PSTC@LISTSERV.IEEE.ORG; oconne...@tamuracorp.com Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. In EMC are testing to 2 kV surge. But Brazil deemed our product telecom and applied 4 kV. A couple of our products spark and arc impressively and continue running. A couple of others quit, died, castors up, and the smoke got out... (It fun when they do that!) EMC says it has to continue to work. Safety says it only has to fail safely. Engineering says fix it but don't change anything. VDR between line and earth, and between line to line fixes it to 4 kV. But I run right into the safety guy and all these notes, about pluggable, single/double fused, screwed down earths, permanent connect, etc. Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives.http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfmif really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Wed, 12/15/10, Brian O'Connell oconne...@tamuracorp.com wrote: From: Brian O'Connell oconne...@tamuracorp.com Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. To: EMC-PSTC@LISTSERV.IEEE.ORG List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, December 15, 2010, 3:33 PM The problem with the VDR being rated for a level 3 surge, which is significantly greater than the typical test V for BI, is that the VDR will typically start conducting long before required test voltage is reached. Di-electric withstand and surge immunity are very different animals. I saw a VDR from line to chassis in a competitor's component P/S - never understood the reason for this construction. Is the VDR rating for 62368 conformity a working voltage or surge rating ? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Richard Nute Sent: Wednesday, December 15, 2010 12:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
A solution we used years ago involved three elements in series, the VDR, a gas tube and a fuse. The gas tube prevented the development of leakage currents as transients age the VDR. If the VDR failed, the fuse prevented full line to neutral fault currents through the gas tube in the event of transients. Removing the fuse also allowed disconnection of the circuit for hipot testing. This was used as a fix for an existing design, but for cost reasons was avoided in new products by better product design. Bob Johnson On 12/15/2010 05:18 PM, JIM WIESE wrote: Thanks Rich, Your first paragraph is what I tried with the safety lab to no avail as they still required a factory hipot, which requires disassembly or some other form of clunky workaround as Brian mentioned. Brian's method could be feasible in some cases from the safety perspective to remove the MOV for the hipot, but lousy if you need a low impedance reliable path for thousands of amps of lightning current. It also is not feasible in most cases for potted or OSP sealed telecom equipment. Merry Christmas, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 4:06 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: If the equipment is permanently grounded, then you can put in a VDR/MOV between mains and ground. Think of a permanent ground as a reinforced safeguard, with no need for basic insulation (in my opinion). For cord-connected equipment, IEC 62368-1 will likely require a series circuit of VDR and gas discharge tube. The big problem with VDR/MOVs is that we don't know the energy that must be dissipated by the VDR/MOV. If the energy is high enough, the VDR/MOV will be destroyed and you will have arcs to ground. Have a Merry Christmas! Rich On 12/15/2010 13:06, JIM WIESE wrote: Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail toemc-p
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
I am not positive, but I think this is just a North American glitch (UL/CSA).I think internationally you could make the justification that Rich pointed out that it is inherently safe and on these products skip a final AC hipot. So what if line and neutral are shorted to ground (other than for functionality reasons). The MOV's will short the line and neutral to ground at a couple hundred volts anyway and could fail short permanently. If it is the case that internationally it isn't a problem, yet somehow domestically it becomes a safety hazard only due to the follow-up services required ac hi-pot aspect, something seems wrong. It just doesn't seem to hold water from a technical basis. Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Kunde, Brian [mailto:brian_ku...@lecotc.com] Sent: Thursday, December 16, 2010 8:17 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Here is another clunky suggestion. What if you put your Surge Suppressor circuit after a dual pole circuit breaker that is only energized when the device is powered up. That way, the VDR is out of the circuit during the Hipot test, but in-circuit during the Surge Immunity test. This brings up a good point in regards to production hipot testing. Some of our instruments have double pole relays, so during hipot those downstream circuits do not get tested. So those circuits have to be individually hipot tested before the side panels are installed. As you said, this goes against the intent of the production hipot test, but what else can you do? You do the best you can. If an inspector disagrees, have him give you the solution. The Other Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of JIM WIESE Sent: Wednesday, December 15, 2010 5:18 PM To: ri...@ieee.org Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Thanks Rich, Your first paragraph is what I tried with the safety lab to no avail as they still required a factory hipot, which requires disassembly or some other form of clunky workaround as Brian mentioned. Brian's method could be feasible in some cases from the safety perspective to remove the MOV for the hipot, but lousy if you need a low impedance reliable path for thousands of amps of lightning current. It also is not feasible in most cases for potted or OSP sealed telecom equipment. Merry Christmas, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 4:06 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: If the equipment is permanently grounded, then you can put in a VDR/MOV between mains and ground. Think of a permanent ground as a reinforced safeguard, with no need for basic insulation (in my opinion). For cord-connected equipment, IEC 62368-1 will likely require a series circuit of VDR and gas discharge tube. The big problem with VDR/MOVs is that we don't know the energy that must be dissipated by the VDR/MOV. If the energy is high enough, the VDR/MOV will be destroyed and you will have arcs to ground. Have a Merry Christmas! Rich On 12/15/2010 13:06, JIM WIESE wrote: Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Here is another clunky suggestion. What if you put your Surge Suppressor circuit after a dual pole circuit breaker that is only energized when the device is powered up. That way, the VDR is out of the circuit during the Hipot test, but in-circuit during the Surge Immunity test. This brings up a good point in regards to production hipot testing. Some of our instruments have double pole relays, so during hipot those downstream circuits do not get tested. So those circuits have to be individually hipot tested before the side panels are installed. As you said, this goes against the intent of the production hipot test, but what else can you do? You do the best you can. If an inspector disagrees, have him give you the solution. The Other Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of JIM WIESE Sent: Wednesday, December 15, 2010 5:18 PM To: ri...@ieee.org Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Thanks Rich, Your first paragraph is what I tried with the safety lab to no avail as they still required a factory hipot, which requires disassembly or some other form of clunky workaround as Brian mentioned. Brian's method could be feasible in some cases from the safety perspective to remove the MOV for the hipot, but lousy if you need a low impedance reliable path for thousands of amps of lightning current. It also is not feasible in most cases for potted or OSP sealed telecom equipment. Merry Christmas, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 4:06 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: If the equipment is permanently grounded, then you can put in a VDR/MOV between mains and ground. Think of a permanent ground as a reinforced safeguard, with no need for basic insulation (in my opinion). For cord-connected equipment, IEC 62368-1 will likely require a series circuit of VDR and gas discharge tube. The big problem with VDR/MOVs is that we don't know the energy that must be dissipated by the VDR/MOV. If the energy is high enough, the VDR/MOV will be destroyed and you will have arcs to ground. Have a Merry Christmas! Rich On 12/15/2010 13:06, JIM WIESE wrote: Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test
RE: OT A BIT........ [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
And then there's the EMC surge test, where the equipment must operate (main fuse not open) after the surge. James Goedderz Sr. Principal Engineer-Product Safety Sensormatic Electronics, LLC 561.912.6378 -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Brian O'Connell Sent: Wednesday, December 15, 2010 8:01 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: OT A BIT [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. The requirement for secondary protection is based on the results of Type Tests for components that are across the line, and the requirements found in 1.5.9.2. The assumption is that the component is rated to be used across mains, and the box is Class I construction. The best result for a surge is that when the varistor (MOV) conducts, the fault current has a low-Z path to the current interrupt device (input fuse) which quickly opens. In this case, the 'additional' protection is provided by a typical input fuse. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Spencer, David H Sent: Wednesday, December 15, 2010 4:12 PM To: Bill Owsley; EMC-PSTC@LISTSERV.IEEE.ORG; oconne...@tamuracorp.com Subject: RE: OT A BIT [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. My safety people are telling me that part of Ed. 2 also requires that VDR's line to line ( or line to neutral) have secondary protection. Either a fuse, gas tube, or double insulated cap.They have been with great gusto been pulling out the VDR's or replacing them with fused versions. From an EMC aspect, we never know when a VDR (from now on MOV) goes bad. SO with respect to line to line (neutral) MOV's only and Ed.2 Do MOV's need a secondary protection? thanks for any comments Regards David Spencer EHS EMC Engineer Xerox Corp Is the VDR rating for 62368 conformity a working voltage or surge rating ? - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
I found this in UL 60950, clause 1.5.9.1: -- quote --- If a surge suppressor is used in a PRIMARY CIRCUIT, it shall be a VDR and it shall comply with Annex Q. NOTE 1 A VDR is sometimes referred to as a varistor or a metal oxide varistor (MOV). Devices such as gas discharge tubes, carbon blocks and semiconductor devices with non-linear voltage/current characteristics are not considered as VDRs in this standard. --- end quote --- This sounds like it prevents the use of VDR/gas discharge tube combinations to limit primary-to-earth line surges, or gas discharge tubes in the primary completely. Is this correct? I'll bet the gas tube companies are having heartburn over this. Pat Lawler EMC Engineer SL Power Electronics Corp. ri...@ieee.org wrote on 12/15/2010 12:05:18 PM: On 12/15/2010 11:41, Kunde, Brian wrote: Does it make VDRs safer to use them in series with a gas-tube like some do with Varistors? Hi Brian: Yes. Today, this is the trend among manufacturers that want to use a VDR between mains and earth. And, TC108 is still trying to sort out the requirements for both devices in such a circuit. Best wishes for a Merry Christmas, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: OT A BIT........ [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
The requirement for secondary protection is based on the results of Type Tests for components that are across the line, and the requirements found in 1.5.9.2. The assumption is that the component is rated to be used across mains, and the box is Class I construction. The best result for a surge is that when the varistor (MOV) conducts, the fault current has a low-Z path to the current interrupt device (input fuse) which quickly opens. In this case, the 'additional' protection is provided by a typical input fuse. Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Spencer, David H Sent: Wednesday, December 15, 2010 4:12 PM To: Bill Owsley; EMC-PSTC@LISTSERV.IEEE.ORG; oconne...@tamuracorp.com Subject: RE: OT A BIT [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. My safety people are telling me that part of Ed. 2 also requires that VDR's line to line ( or line to neutral) have secondary protection. Either a fuse, gas tube, or double insulated cap.They have been with great gusto been pulling out the VDR's or replacing them with fused versions. From an EMC aspect, we never know when a VDR (from now on MOV) goes bad. SO with respect to line to line (neutral) MOV's only and Ed.2 Do MOV's need a secondary protection? thanks for any comments Regards David Spencer EHS EMC Engineer Xerox Corp Is the VDR rating for 62368 conformity a working voltage or surge rating ? - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: OT A BIT........ [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
My safety people are telling me that part of Ed. 2 also requires that VDR's line to line ( or line to neutral) have secondary protection. Either a fuse, gas tube, or double insulated cap.They have been with great gusto been pulling out the VDR's or replacing them with fused versions. From an EMC aspect, we never know when a VDR (from now on MOV) goes bad. SO with respect to line to line (neutral) MOV's only and Ed.2 Do MOV's need a secondary protection? thanks for any comments Regards David Spencer EHS EMC Engineer Xerox Corp -Original Message- From: emc-p...@ieee.org on behalf of Bill Owsley Sent: Wed 12/15/2010 3:57 PM To: EMC-PSTC@LISTSERV.IEEE.ORG; oconne...@tamuracorp.com Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. In EMC are testing to 2 kV surge. But Brazil deemed our product telecom and applied 4 kV. A couple of our products spark and arc impressively and continue running. A couple of others quit, died, castors up, and the smoke got out... (It fun when they do that!) EMC says it has to continue to work. Safety says it only has to fail safely. Engineering says fix it but don't change anything. VDR between line and earth, and between line to line fixes it to 4 kV. But I run right into the safety guy and all these notes, about pluggable, single/double fused, screwed down earths, permanent connect, etc. Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives.http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfmif really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Wed, 12/15/10, Brian O'Connell oconne...@tamuracorp.com wrote: From: Brian O'Connell oconne...@tamuracorp.com Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. To: EMC-PSTC@LISTSERV.IEEE.ORG List-Post: emc-pstc@listserv.ieee.org Date: Wednesday, December 15, 2010, 3:33 PM The problem with the VDR being rated for a level 3 surge, which is significantly greater than the typical test V for BI, is that the VDR will typically start conducting long before required test voltage is reached. Di-electric withstand and surge immunity are very different animals. I saw a VDR from line to chassis in a competitor's component P/S - never understood the reason for this construction. Is the VDR rating for 62368 conformity a working voltage or surge rating ? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Richard Nute Sent: Wednesday, December 15, 2010 12:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Thanks Rich, Your first paragraph is what I tried with the safety lab to no avail as they still required a factory hipot, which requires disassembly or some other form of clunky workaround as Brian mentioned. Brian's method could be feasible in some cases from the safety perspective to remove the MOV for the hipot, but lousy if you need a low impedance reliable path for thousands of amps of lightning current. It also is not feasible in most cases for potted or OSP sealed telecom equipment. Merry Christmas, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 4:06 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: If the equipment is permanently grounded, then you can put in a VDR/MOV between mains and ground. Think of a permanent ground as a reinforced safeguard, with no need for basic insulation (in my opinion). For cord-connected equipment, IEC 62368-1 will likely require a series circuit of VDR and gas discharge tube. The big problem with VDR/MOVs is that we don't know the energy that must be dissipated by the VDR/MOV. If the energy is high enough, the VDR/MOV will be destroyed and you will have arcs to ground. Have a Merry Christmas! Rich On 12/15/2010 13:06, JIM WIESE wrote: Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Hi Jim: If the equipment is permanently grounded, then you can put in a VDR/MOV between mains and ground. Think of a permanent ground as a reinforced safeguard, with no need for basic insulation (in my opinion). For cord-connected equipment, IEC 62368-1 will likely require a series circuit of VDR and gas discharge tube. The big problem with VDR/MOVs is that we don't know the energy that must be dissipated by the VDR/MOV. If the energy is high enough, the VDR/MOV will be destroyed and you will have arcs to ground. Have a Merry Christmas! Rich On 12/15/2010 13:06, JIM WIESE wrote: Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Hi Brian: You describe the problem accurately. The VDR will start conducting before the required test voltage is reached. From a safety point of view, this is not acceptable unless the equipment is reliably grounded. From a functional point of view, this is the intended performance. Let's put it this way. Normal mains voltage is comprised of two elements: mains operating voltage; mains transient voltage. The safety of the equipment is dependent upon the mains insulation (between mains and accessible parts, including ground) being able to withstand both voltages. As near as I can discern, surge immunity is the same as mains transient withstand. Surge immunity implies withstanding a 1.2x50 impulse waveform, while mains transient withstand implies a sinewave. (The mains transient withstand test can be done with a sinewave, DC, or a 1.2x50 impulse.) The IEC 62368-1 requirement is that EVERYTHING connected between mains and earth must pass a dielectric withstand test. Have a Merry Christmas, Rich On 12/15/2010 12:33, Brian O'Connell wrote: The problem with the VDR being rated for a level 3 surge, which is significantly greater than the typical test V for BI, is that the VDR will typically start conducting long before required test voltage is reached. Di-electric withstand and surge immunity are very different animals. I saw a VDR from line to chassis in a competitor's component P/S - never understood the reason for this construction. Is the VDR rating for 62368 conformity a working voltage or surge rating ? Brian - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Hey Rich, The reason for VDR's (MOV's) to ground is to prevent arcing to the chassis for customers that demand either 6KV or 10KV lightning tests. The products are permanently grounded so the arcing to ground is not a safety hazard at those levels. The products easily pass the hipot without the MOV's to several KV (well above the hipot level). The arcing at 6 or 10KV often functionally kills the supply or other circuitry, which of course 60950 could not care less about functionality. But other standards do. It sounds like IEC 62368 will mess up using MOV's to ground though as I am not aware of MOV's rated several KV. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 2:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich On 12/15/2010 11:27, JIM WIESE wrote: Rich, The issue we ran into with this is that UL and other NRTL's require factory hi-pot testing on AC interfaces as part of follow-up services. The product will obviously fail at that point. The original 60950-1 safety testing is done with the VDR's removed. But for the factory hi-pot the VDR's often cannot be removed without disassembly of the product, and even if they could be removed it violates the intent of the test, which is to perform the factory hi-pot right before it is boxed up for shipping, not rip it apart, do a hipot, and then re-assemble the product. As you point out the conditions necessary to allow the VDR's to ground in the first place already require the assumption that the VDR can go short and not create a hazard. So 60950-1 now allows the VDR's to ground, but the follow-up services and listing requirements for the factory hi-pot here in the US and Canada more or less prevent doing it. So, there should be some kind of waiver from the factory hi-pot if the product has VDR's to ground as permitted in 60950-1, but unless that happens it is silly to allow it in the UL/CSA version, unless people feel tearing a product apart to disable VDR's, then doing a hi-pot, then reassembling the equipment makes sense. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
In EMC are testing to 2 kV surge. But Brazil deemed our product telecom and applied 4 kV. A couple of our products spark and arc impressively and continue running. A couple of others quit, died, castors up, and the smoke got out... (It fun when they do that!) EMC says it has to continue to work. Safety says it only has to fail safely. Engineering says fix it but don't change anything. VDR between line and earth, and between line to line fixes it to 4 kV. But I run right into the safety guy and all these notes, about pluggable, single/double fused, screwed down earths, permanent connect, etc. Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives. http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfm if really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Wed, 12/15/10, Brian O'Connell oconne...@tamuracorp.com wrote: From: Brian O'Connell oconne...@tamuracorp.com Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. To: EMC-PSTC@LISTSERV.IEEE.ORG Date: Wednesday, December 15, 2010, 3:33 PM The problem with the VDR being rated for a level 3 surge, which is significantly greater than the typical test V for BI, is that the VDR will typically start conducting long before required test voltage is reached. Di-electric withstand and surge immunity are very different animals. I saw a VDR from line to chassis in a competitor's component P/S - never understood the reason for this construction. Is the VDR rating for 62368 conformity a working voltage or surge rating ? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Richard Nute Sent: Wednesday, December 15, 2010 12:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
The problem with the VDR being rated for a level 3 surge, which is significantly greater than the typical test V for BI, is that the VDR will typically start conducting long before required test voltage is reached. Di-electric withstand and surge immunity are very different animals. I saw a VDR from line to chassis in a competitor's component P/S - never understood the reason for this construction. Is the VDR rating for 62368 conformity a working voltage or surge rating ? Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org]On Behalf Of Richard Nute Sent: Wednesday, December 15, 2010 12:01 PM To: JIM WIESE Cc: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
On 12/15/2010 11:41, Kunde, Brian wrote: Does it make VDRs safer to use them in series with a gas-tube like some do with Varistors? Hi Brian: Yes. Today, this is the trend among manufacturers that want to use a VDR between mains and earth. And, TC108 is still trying to sort out the requirements for both devices in such a circuit. Best wishes for a Merry Christmas, Rich - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Hi Jim: Thanks for your remarks. You CAN remove the VDR during hi-pot testing. This is specified in 5.2.2: To avoid damage to components or insulation that are not involved in the test, disconnection of integrated circuits or the like and the use of equipotential bonding are permitted. This is for the type test, not the routine test. Nevertheless, your point is well taken. Also note that 5.2.1 specifies: The electric strength of the SOLID INSULATION used in the equipment shall be adequate. So, the hi-pot test only applies to solid insulation. The other option is to specify the VDR at a higher voltage than the hi-pot test voltage. Regarding VDRs, I don't know why any equipment would need a VDR between mains and earth. The requirements for clearance, creepage, and solid insulations require an electric strength at least as great as the expected transient overvoltage, regardless whether a VDR is between mains and earth or not. So, the VDR does not protect anything against any voltage up to the required electric strength of the equipment. The VDR *may* be useful to protect against transient voltages exceeding the required electric strength.n which case it will pass the hi-pot test. In the new IEC 62368, the requirement is that any VDR between mains and earth shall be rated greater than the required electric strength. Best wishes for the Christmas season, Rich On 12/15/2010 11:27, JIM WIESE wrote: Rich, The issue we ran into with this is that UL and other NRTL's require factory hi-pot testing on AC interfaces as part of follow-up services. The product will obviously fail at that point. The original 60950-1 safety testing is done with the VDR's removed. But for the factory hi-pot the VDR's often cannot be removed without disassembly of the product, and even if they could be removed it violates the intent of the test, which is to perform the factory hi-pot right before it is boxed up for shipping, not rip it apart, do a hipot, and then re-assemble the product. As you point out the conditions necessary to allow the VDR's to ground in the first place already require the assumption that the VDR can go short and not create a hazard. So 60950-1 now allows the VDR's to ground, but the follow-up services and listing requirements for the factory hi-pot here in the US and Canada more or less prevent doing it. So, there should be some kind of waiver from the factory hi-pot if the product has VDR's to ground as permitted in 60950-1, but unless that happens it is silly to allow it in the UL/CSA version, unless people feel tearing a product apart to disable VDR's, then doing a hi-pot, then reassembling the equipment makes sense. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Does it make VDRs safer to use them in series with a gas-tube like some do with Varistors? I've never seen it done but I was told years ago that some companies have a screw in the back of their products that connects the chassis/earth ground connection to their surge suppression circuit. The screw is removed to break the ground point during the hipot test, then reinstalled after the test. The Other Brian -Original Message- From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of JIM WIESE Sent: Wednesday, December 15, 2010 2:28 PM To: ri...@ieee.org; EMC-PSTC@LISTSERV.IEEE.ORG Subject: RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Rich, The issue we ran into with this is that UL and other NRTL's require factory hi-pot testing on AC interfaces as part of follow-up services. The product will obviously fail at that point. The original 60950-1 safety testing is done with the VDR's removed. But for the factory hi-pot the VDR's often cannot be removed without disassembly of the product, and even if they could be removed it violates the intent of the test, which is to perform the factory hi-pot right before it is boxed up for shipping, not rip it apart, do a hipot, and then re-assemble the product. As you point out the conditions necessary to allow the VDR's to ground in the first place already require the assumption that the VDR can go short and not create a hazard. So 60950-1 now allows the VDR's to ground, but the follow-up services and listing requirements for the factory hi-pot here in the US and Canada more or less prevent doing it. So, there should be some kind of waiver from the factory hi-pot if the product has VDR's to ground as permitted in 60950-1, but unless that happens it is silly to allow it in the UL/CSA version, unless people feel tearing a product apart to disable VDR's, then doing a hi-pot, then reassembling the equipment makes sense. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 1:02 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Donald: A VDR is taken as a device that is likely to fail. If the VDR is connected between mains and the protective earthing system, then the PE system must be considered reliable, that is, equivalent to a reinforced safeguard. Ever since the days of 2-wire plugs and sockets, grounding by means of a domestic plug and socket has not been considered reliable (because you could not predict whether the installation was 2-wire or 2-wire plus ground). In order to have a reliable ground, the ground construction must be permanent or equivalent. (Equivalent is taken as by means of industrial- grade plug and socket schemes.) 1.5.9.4 specifies the equivalent grounding schemes. Yes, you are correct in that a VDR is not permitted to be connected to earth (ground) in pluggable equipment type A. Best wishes for a Merry Christmas, Richard Nute Product Safety Consultant San Diego On 12/14/2010 14:20, Donald McElheran wrote: All: Under clause 1.5.9.4 Bridging of basic insulation by a VDR in the latest version of 60950-1 Paragraph two: Equipment with such a VDR bridging insulation shall be one of the following: - equipment that has the provision for a permanently connected PROTECTIVE EARTHING CONNECTOR and is provided with instructions for the installation of that conductor. This requirement appears to rule out the use of power supplies making use of earthed VDRs in their primary circuits, if used in Pluggable Equipment Type A if a separate earthing terminal is not provided. Could anyone confirm that this interpretion is correct and wether this was the intent of the committee. Donald McElheran Product Compliance Specialist Ross Video | Live Production Technology www.rossvideo.com +1 (613) 652-4886 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Rich, The issue we ran into with this is that UL and other NRTL's require factory hi-pot testing on AC interfaces as part of follow-up services. The product will obviously fail at that point. The original 60950-1 safety testing is done with the VDR's removed. But for the factory hi-pot the VDR's often cannot be removed without disassembly of the product, and even if they could be removed it violates the intent of the test, which is to perform the factory hi-pot right before it is boxed up for shipping, not rip it apart, do a hipot, and then re-assemble the product. As you point out the conditions necessary to allow the VDR's to ground in the first place already require the assumption that the VDR can go short and not create a hazard. So 60950-1 now allows the VDR's to ground, but the follow-up services and listing requirements for the factory hi-pot here in the US and Canada more or less prevent doing it. So, there should be some kind of waiver from the factory hi-pot if the product has VDR's to ground as permitted in 60950-1, but unless that happens it is silly to allow it in the UL/CSA version, unless people feel tearing a product apart to disable VDR's, then doing a hi-pot, then reassembling the equipment makes sense. Best regards, Jim Jim Wiese Senior Compliance Engineer ADTRAN, Inc. 901 Explorer Blvd. Huntsville, AL 35806 256-963-8431 256-714-5882 (cell) 256-963-6218 (fax) jim.wi...@adtran.com -Original Message- From: Richard Nute [mailto:rn...@san.rr.com] Sent: Wednesday, December 15, 2010 1:02 PM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: Re: [PSES] IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation. Hi Donald: A VDR is taken as a device that is likely to fail. If the VDR is connected between mains and the protective earthing system, then the PE system must be considered reliable, that is, equivalent to a reinforced safeguard. Ever since the days of 2-wire plugs and sockets, grounding by means of a domestic plug and socket has not been considered reliable (because you could not predict whether the installation was 2-wire or 2-wire plus ground). In order to have a reliable ground, the ground construction must be permanent or equivalent. (Equivalent is taken as by means of industrial- grade plug and socket schemes.) 1.5.9.4 specifies the equivalent grounding schemes. Yes, you are correct in that a VDR is not permitted to be connected to earth (ground) in pluggable equipment type A. Best wishes for a Merry Christmas, Richard Nute Product Safety Consultant San Diego On 12/14/2010 14:20, Donald McElheran wrote: All: Under clause 1.5.9.4 Bridging of basic insulation by a VDR in the latest version of 60950-1 Paragraph two: Equipment with such a VDR bridging insulation shall be one of the following: - equipment that has the provision for a permanently connected PROTECTIVE EARTHING CONNECTOR and is provided with instructions for the installation of that conductor. This requirement appears to rule out the use of power supplies making use of earthed VDRs in their primary circuits, if used in Pluggable Equipment Type A if a separate earthing terminal is not provided. Could anyone confirm that this interpretion is correct and wether this was the intent of the committee. Donald McElheran Product Compliance Specialist Ross Video | Live Production Technology www.rossvideo.com +1 (613) 652-4886 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David
Re: IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
Hi Donald: A VDR is taken as a device that is likely to fail. If the VDR is connected between mains and the protective earthing system, then the PE system must be considered reliable, that is, equivalent to a reinforced safeguard. Ever since the days of 2-wire plugs and sockets, grounding by means of a domestic plug and socket has not been considered reliable (because you could not predict whether the installation was 2-wire or 2-wire plus ground). In order to have a reliable ground, the ground construction must be permanent or equivalent. (Equivalent is taken as by means of industrial- grade plug and socket schemes.) 1.5.9.4 specifies the equivalent grounding schemes. Yes, you are correct in that a VDR is not permitted to be connected to earth (ground) in pluggable equipment type A. Best wishes for a Merry Christmas, Richard Nute Product Safety Consultant San Diego On 12/14/2010 14:20, Donald McElheran wrote: All: Under clause 1.5.9.4 Bridging of basic insulation by a VDR in the latest version of 60950-1 Paragraph two: Equipment with such a VDR bridging insulation shall be one of the following: - equipment that has the provision for a permanently connected PROTECTIVE EARTHING CONNECTOR and is provided with instructions for the installation of that conductor. This requirement appears to rule out the use of power supplies making use of earthed VDRs in their primary circuits, if used in Pluggable Equipment Type A if a separate earthing terminal is not provided. Could anyone confirm that this interpretion is correct and wether this was the intent of the committee. Donald McElheran Product Compliance Specialist Ross Video | Live Production Technology www.rossvideo.com +1 (613) 652-4886 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
IEC 60950-1 Ed. 2 Class A Pluggable equipment and VDR bridging basic insulation.
All: Under clause 1.5.9.4 Bridging of basic insulation by a VDR in the latest version of 60950-1 Paragraph two: Equipment with such a VDR bridging insulation shall be one of the following: - equipment that has the provision for a permanently connected PROTECTIVE EARTHING CONNECTOR and is provided with instructions for the installation of that conductor. This requirement appears to rule out the use of power supplies making use of earthed VDRs in their primary circuits, if used in Pluggable Equipment Type A if a separate earthing terminal is not provided. Could anyone confirm that this interpretion is correct and wether this was the intent of the committee. Donald McElheran Product Compliance Specialist Ross Video | Live Production Technology www.rossvideo.com +1 (613) 652-4886 - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to emc-p...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@radiusnorth.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: dhe...@gmail.com
RE: 10/100 Ethernet transformers meeting IEC60950 Basic insulation
Thank you for the update, John. I didn't plan to look it up; it's kind of you to do so for us. The document contains a number of other items, not related to reliance on enamel magnet wire as insulation. Could've bounced on any or all accounts. Regards, Peter L. Tarver, PE ptar...@ieee.org From: John Woodgate Sent: Friday, November 14, 2003 1:12 PM Peter L. Tarver wrote: FWIW, there is a proposal in TC108 (108/69/CD) to permit limited use of enameled magnet wire for compliance with TNV-x requirements. I don't know the current status of this document and can not accurately predict (who can?) it's complexion in final for. You can get a lot of information from the public part of the IEC web site: Committee 108 Current document 108/69/CD Current status 1CD - 1st Committee Draft Title: Modifications in clause 2.10 and Annex G Remarks: - CDV 2004-04 FDIS 2004-11 [These are forecasts made at an early stage] HISTORY OF THE PROJECT StageDocument DateTarget Date AMW 108/86/MCR 4 July 2003 1CD 108/69/CD 4 July 2003 A2CD 30 November 2003 From this we can conclude that the reaction of National Committees to the 1CD, 108/69/CD, was less than enthusiastic (otherwise it would have gone to CDV - first voting stage) and a second CD will be circulated. Theoretically, the schedule for CDV in April 2004 could JUST still be met, but probably it won't be. -- 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: 10/100 Ethernet transformers meeting IEC60950 Basic insulation
I read in !emc-pstc that Peter L. Tarver peter.tar...@sanmina-sci.com wrote (in nebbkemlgllmjofmopleaeilenaa.peter.tar...@sanmina-sci.com) about '10/100 Ethernet transformers meeting IEC60950 Basic insulation' on Fri, 14 Nov 2003: FWIW, there is a proposal in TC108 (108/69/CD) to permit limited use of enameled magnet wire for compliance with TNV-x requirements. I don't know the current status of this document and can not accurately predict (who can?) it's complexion in final for. You can get a lot of information from the public part of the IEC web site: Committee 108 Current document 108/69/CD Current status 1CD - 1st Committee Draft Title: Modifications in clause 2.10 and Annex G Remarks: - CDV 2004-04 FDIS 2004-11 [These are forecasts made at an early stage] HISTORY OF THE PROJECT StageDocument DateTarget Date AMW 108/86/MCR 4 July 2003 1CD 108/69/CD 4 July 2003 A2CD 30 November 2003 From this we can conclude that the reaction of National Committees to the 1CD, 108/69/CD, was less than enthusiastic (otherwise it would have gone to CDV - first voting stage) and a second CD will be circulated. Theoretically, the schedule for CDV in April 2004 could JUST still be met, but probably it won't be. -- 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: 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: 10/100 Ethernet transformers meeting IEC60950 Basic insulation
There is such beast made by pca electronics (www.pca.com). The part number is EPF819 SL. I have the datasheet if anyone wants it. Doug Peter L. Tarver peter.tarver@sanmina- To: emc-pstc emc-p...@majordomo.ieee.org sci.com cc: Charles Blackham cblac...@airspan.com Sent by: Subject: RE: 10/100 Ethernet transformers meeting IEC60950 Basic insulation owner-emc-pstc@majordo mo.ieee.org 11/14/03 11:07 AM Please respond to Peter L. Tarver Charles - From: Charles Blackham Sent: Friday, November 14, 2003 5:54 AM I wish to provide a safety barrier between the User connecting to the 10/100 RJ45 Ethernet port and the TNV3 circuitry within my unit. Can anyone recommend a suitable Ethernet transformer that is a UL recognised component and meets the Creepage and clearance distances for Basic insulation? I'm not aware of any ethernet transformers that provide Basic Insulation, but there may be some. All I can suggest is to try the big players: Midcom, Pulse, Bel Fuse, et al. Each of those mentioned have telephony transformers that meet Basic Insulation requirements. I don't know the innards of your equipment, but it would seem easier to use a barrier at the TNV-3 interface and have the remainder of the product's secondary circuits be SELV. There are circumstances I've come across that don't make this practical (for instance, a large systems) and there are ways around the construction requirement for most markets (certain Nordics excluded). Alternatively, can I use rely on the through insulation breakdown of the enamel insulation and potting on a bi-filar wound core? Do I just have to meet the electric strength test, or am I missing something here? In general, no, you can't rely on this. For Canada and the US, there are some special cases where magnet wire is allowed to provide insulation (not simply isolation) in a TNV-2 or -3 circuit, but I don't think you'll find an ethernet transformer that you can guarantee will meet these requirements. FWIW, there is a proposal in TC108 (108/69/CD) to permit limited use of enameled magnet wire for compliance with TNV-x requirements. I don't know the current status of this document and can not accurately predict (who can?) it's complexion in final for. Good luck. Regards, Peter L. Tarver, PE ptar...@ieee.org This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: 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
10/100 Ethernet transformers meeting IEC60950 Basic insulation
All I wish to provide a safety barrier between the User connecting to the 10/100 RJ45 Ethernet port and the TNV3 circuitry within my unit. Can anyone recommend a suitable Ethernet transformer that is a UL recognised component and meets the Creepage and clearance distances for Basic insulation? Alternatively, can I use rely on the through insulation breakdown of the enamel insulation and potting on a bi-filar wound core? Do I just have to meet the electric strength test, or am I missing something here? regards Charlie Blackham
Ethernet transformer that meets 60950 basic insulation requirements
Hi Someone on the list was asking a week or so ago about an ethernet transformer that meets the 60950 basic insulation requirements. Forgive me, my brain is little and I forgot who. I have the information on the part, so whoever it was, please email me and I will send it to you. Regards Doug Beckwith Mitel Networks 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: Is this a case of basic insulation?
Another option is to use contiguous sleeving and clamps whose mounting features do not require penetrating the sleeving. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com From: don_borow...@selinc.com Sent: Friday, January 17, 2003 8:38 AM If polymeric hardware can't handle the heat, one could use ceramic hardware. I just received some product info from a company called Ceramco www.ceramcoceramics.com that among other things produces a line of ceramic nuts, bolts and washers. Don Borowski 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: Is this a case of basic insulation?
I assume this is an off line switcher. If so, the FET is at mains potential and the required creepage and clearance distances is the same as the hot-to-ground creepage requirement(4 mm or is it 3 mm? for creepage). I would not use the chassis as a heatsink myself. Even dirt cheap PC power supplies don't do this. But if you must, is a heatsink pad defined as single insulated? You might need two pads to constitute double insulation. Another route is to use a full-pack FET (already encased in an insulating material) along with a pad. But do we define creepage under the assumption that one insulation layer has a defect? If so then the full-pack and pad will not do if we assume that the pad has a defect. The FET could be held with a clamp of some sort. This FET-insulation-chassis arrangement will have quite a bit of thermal resistance You can calculate this and might find that you are better off thermally and cost-wise with a small heatsink attached directly to the FET and floating at mains potential. To reduce the E-field noise being thrown around, by the heatsink connected to the FET Drain, you can use a full-pack FET and connect the heatsink to the floating circuit common. In this case you will not need a pad and I wouldn't bother with heatsink paste. A package such as a TO220 or TO218, when mounted on a flat heatsink, will work just fine without that messy paste. I also wouldn't worry about the junction temp if it is 100 C and even 125 C is acceptable. I see engineers spending too much time and money trying to keep junction temperatures luke warm. I can get into a whole page on reliability in the real world (and how to calculate it and how some methods are bogus) but will spare you at this time. Dave Cuthbert Micron Technology From: Peter L. Tarver [mailto:peter.tar...@sanmina-sci.com] Sent: Friday, January 17, 2003 8:26 AM To: EMC-PSTC (E-mail) Subject: RE: Is this a case of basic insulation? Vic - Your assumption that at least Basic insulation is required is correct. However, creepage distances are based on rms voltages, not peak. The below assumes that the voltages you mentioned are present on the heatsink of the FET. Assuming that a true rms meter will indicate an rms voltage between 250 Vrms and 300 Vrms, the minimum require creepage from Table 2L is 3.2 mm. Based on the peak voltage you mentioned, the minimum required clearance distance from Table 2H is 2.0 mm, plus the added distance from Table 2J of 0.2, gives a total minimum clearance distance of 2.2 mm. Without knowing the particulars of the FET and its heatsink in any great detail, an insulating pad is an appropriate and common means of complying with the standard. Unless you can demonstrate that the pad will not compress to less than 3.2 mm thickness in the application, you'll probably need a shouldered washer or something similar to add additional creepage between the screw shank and the FET's heatsink. Polymeric screws are available, but I can't speak regarding their use in an elevated temperature. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com -Original Message- From: Gibling, Vic Sent: Friday, January 17, 2003 12:00 AM We drive a FET based H-bridge from rectified 230VAC mains; thus 320Vpk across the bridge. We have assumed the insulation between the rectified power return and chassis (Class 1 product) is basic, thus requiring 4mm creepage (IEC950). The proposed FETs need to be attached to a heat sink and we would like to use the chassis for this purpose. Our problem is that the FETs have around 2mm creepage between their exposed heatsink surface and the fixing screw, insufficient to meet the basic insulation creepage distance. Is our interpretation regarding basic insulation correct/reasonable? If we use an insulative thermal pad between the FET and chassis, does the compression of the pad exclude the air path thus offering sufficient protection? I am aware of such pads offering 4.5kV breakdown. Thank you Vic Gibling Compliance Engineer e2v technologies Ltd Waterhouse Lane Chelmsford ESSEX CM1 2QU Telephone: +44 (0) 01245 493493 Direct Line: +44 (0) 01245 453352 Facsimile: +44 (0) 01245 453410 E-mail: vic.gibl...@e2vtechnologies.com Internet: www.e2vtechnologies.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
RE: Is this a case of basic insulation?
If polymeric hardware can't handle the heat, one could use ceramic hardware. I just received some product info from a company called Ceramco www.ceramcoceramics.com that among other things produces a line of ceramic nuts, bolts and washers. Don Borowski Schweitzer Engineering Labs Pullman, WA Peter L. Tarver peter.tar...@sanmina-sci.com@majordomo.ieee.org on 01/17/2003 07:26:25 AM Please respond to Peter L. Tarver peter.tar...@sanmina-sci.com Sent by:owner-emc-p...@majordomo.ieee.org To:EMC-PSTC \(E-mail\) emc-p...@majordomo.ieee.org cc: Subject:RE: Is this a case of basic insulation? Vic - Your assumption that at least Basic insulation is required is correct. However, creepage distances are based on rms voltages, not peak. The below assumes that the voltages you mentioned are present on the heatsink of the FET. Assuming that a true rms meter will indicate an rms voltage between 250 Vrms and 300 Vrms, the minimum require creepage from Table 2L is 3.2 mm. Based on the peak voltage you mentioned, the minimum required clearance distance from Table 2H is 2.0 mm, plus the added distance from Table 2J of 0.2, gives a total minimum clearance distance of 2.2 mm. Without knowing the particulars of the FET and its heatsink in any great detail, an insulating pad is an appropriate and common means of complying with the standard. Unless you can demonstrate that the pad will not compress to less than 3.2 mm thickness in the application, you'll probably need a shouldered washer or something similar to add additional creepage between the screw shank and the FET's heatsink. Polymeric screws are available, but I can't speak regarding their use in an elevated temperature. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com -Original Message- From: Gibling, Vic Sent: Friday, January 17, 2003 12:00 AM We drive a FET based H-bridge from rectified 230VAC mains; thus 320Vpk across the bridge. We have assumed the insulation between the rectified power return and chassis (Class 1 product) is basic, thus requiring 4mm creepage (IEC950). The proposed FETs need to be attached to a heat sink and we would like to use the chassis for this purpose. Our problem is that the FETs have around 2mm creepage between their exposed heatsink surface and the fixing screw, insufficient to meet the basic insulation creepage distance. Is our interpretation regarding basic insulation correct/reasonable? If we use an insulative thermal pad between the FET and chassis, does the compression of the pad exclude the air path thus offering sufficient protection? I am aware of such pads offering 4.5kV breakdown. Thank you Vic Gibling Compliance Engineer e2v technologies Ltd Waterhouse Lane Chelmsford ESSEX CM1 2QU Telephone: +44 (0) 01245 493493 Direct Line: +44 (0) 01245 453352 Facsimile: +44 (0) 01245 453410 E-mail: vic.gibl...@e2vtechnologies.com Internet: www.e2vtechnologies.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe
RE: Is this a case of basic insulation?
Vic - Your assumption that at least Basic insulation is required is correct. However, creepage distances are based on rms voltages, not peak. The below assumes that the voltages you mentioned are present on the heatsink of the FET. Assuming that a true rms meter will indicate an rms voltage between 250 Vrms and 300 Vrms, the minimum require creepage from Table 2L is 3.2 mm. Based on the peak voltage you mentioned, the minimum required clearance distance from Table 2H is 2.0 mm, plus the added distance from Table 2J of 0.2, gives a total minimum clearance distance of 2.2 mm. Without knowing the particulars of the FET and its heatsink in any great detail, an insulating pad is an appropriate and common means of complying with the standard. Unless you can demonstrate that the pad will not compress to less than 3.2 mm thickness in the application, you'll probably need a shouldered washer or something similar to add additional creepage between the screw shank and the FET's heatsink. Polymeric screws are available, but I can't speak regarding their use in an elevated temperature. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA peter.tar...@sanmina-sci.com -Original Message- From: Gibling, Vic Sent: Friday, January 17, 2003 12:00 AM We drive a FET based H-bridge from rectified 230VAC mains; thus 320Vpk across the bridge. We have assumed the insulation between the rectified power return and chassis (Class 1 product) is basic, thus requiring 4mm creepage (IEC950). The proposed FETs need to be attached to a heat sink and we would like to use the chassis for this purpose. Our problem is that the FETs have around 2mm creepage between their exposed heatsink surface and the fixing screw, insufficient to meet the basic insulation creepage distance. Is our interpretation regarding basic insulation correct/reasonable? If we use an insulative thermal pad between the FET and chassis, does the compression of the pad exclude the air path thus offering sufficient protection? I am aware of such pads offering 4.5kV breakdown. Thank you Vic Gibling Compliance Engineer e2v technologies Ltd Waterhouse Lane Chelmsford ESSEX CM1 2QU Telephone: +44 (0) 01245 493493 Direct Line: +44 (0) 01245 453352 Facsimile: +44 (0) 01245 453410 E-mail: vic.gibl...@e2vtechnologies.com Internet: www.e2vtechnologies.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
Is this a case of basic insulation?
Hi to you all, We would appreciate your views please. We drive a FET based H-bridge from rectified 230VAC mains; thus 320Vpk across the bridge. We have assumed the insulation between the rectified power return and chassis (Class 1 product) is basic, thus requiring 4mm creepage (IEC950). The proposed FETs need to be attached to a heat sink and we would like to use the chassis for this purpose. Our problem is that the FETs have around 2mm creepage between their exposed heatsink surface and the fixing screw, insufficient to meet the basic insulation creepage distance. Is our interpretation regarding basic insulation correct/reasonable? If we use an insulative thermal pad between the FET and chassis, does the compression of the pad exclude the air path thus offering sufficient protection? I am aware of such pads offering 4.5kV breakdown. Thank you Vic Gibling Compliance Engineer e2v technologies Ltd Waterhouse Lane Chelmsford ESSEX CM1 2QU Telephone: +44 (0) 01245 493493 Direct Line: +44 (0) 01245 453352 Facsimile: +44 (0) 01245 453410 E-mail: vic.gibl...@e2vtechnologies.com Internet: www.e2vtechnologies.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: DC/DC Convertor with BASIC INSULATION
Hi Peter, Try Vicor. Mike Harris/Teccom -Original Message- From: Peter Merguerian pmerguer...@itl.co.il To: EMC-PSTC (E-mail) emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Friday, May 04, 2001 2:25 AM Subject: DC/DC Convertor with BASIC INSULATION Dear All, Does anyone have a list of manufacturers of Approved (UL Recognized/ TUV Approved) 36-72V range dc/dc convertor with the following characteristics and at least BASIC INSULATION between the input and output? The dc/dc converor will be used for a telecom device intended for connection to a Centralized DC source of supply. 3.3V/20A in Quarter Brick 3.3V/10A in Quarter Brick 2.5V/20A in Quarter Brick 1.8V/40A in Half Brick PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 Mobile: 972-54-838175 --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@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://www.rcic.com/ click on Virtual Conference Hall, --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@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://www.rcic.com/ click on Virtual Conference Hall,
RE: DC/DC Convertor with BASIC INSULATION
SynQor Lucent/Tyco di/dt Power One Hope that this helps David B. Goldstein Principal Manufacturing Engineer Cratos Networks 313 Littleton Rd; Suite 20 Chelmsford, MA 01824 978-244-0068 ext. 150 FAX (978) 244-0618 dgoldst...@cratosnetworks.com -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Friday, May 04, 2001 4:55 AM To: EMC-PSTC (E-mail) Subject: DC/DC Convertor with BASIC INSULATION Dear All, Does anyone have a list of manufacturers of Approved (UL Recognized/ TUV Approved) 36-72V range dc/dc convertor with the following characteristics and at least BASIC INSULATION between the input and output? The dc/dc converor will be used for a telecom device intended for connection to a Centralized DC source of supply. 3.3V/20A in Quarter Brick 3.3V/10A in Quarter Brick 2.5V/20A in Quarter Brick 1.8V/40A in Half Brick PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 Mobile: 972-54-838175 --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@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://www.rcic.com/ click on Virtual Conference Hall, attachment: Goldstein,_David.vcf
DC/DC Convertor with BASIC INSULATION
Dear All, Does anyone have a list of manufacturers of Approved (UL Recognized/ TUV Approved) 36-72V range dc/dc convertor with the following characteristics and at least BASIC INSULATION between the input and output? The dc/dc converor will be used for a telecom device intended for connection to a Centralized DC source of supply. 3.3V/20A in Quarter Brick 3.3V/10A in Quarter Brick 2.5V/20A in Quarter Brick 1.8V/40A in Half Brick PETER S. MERGUERIAN Technical Director I.T.L. (Product Testing) Ltd. 26 Hacharoshet St., POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 Mobile: 972-54-838175 --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@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://www.rcic.com/ click on Virtual Conference Hall,
RE: Suitability of X2 Capacitors as Basic Insulation
Scott, You may be right with UL1950, but EN60950 tells that the CO battery of 72 volt is a TNV-2 circuit that only needs functional insulation w.r.t. PE. If the CO battery voltage in the US is lower than 60 volt dc, it also requires only functional insulation. Best regards, Chris On Fri, 06 October 2000, Scott Lemon wrote: Subject: RE: Suitability of X2 Capacitors as Basic Insulation Return-Path: sle...@caspiannetworks.com Content-Type: text/plain; charset=iso-8859-1 Content-Length: 4101 Mime-Version: 1.0 To: 'Chris Collin' globalass...@altavista.com, pmerguer...@itl.co.il X-Received: 6 Oct 2000 21:06:06 GMT Delivered-To: altavista.com%globalass...@altavista.com From: Scott Lemon sle...@caspiannetworks.com Date: Fri, 6 Oct 2000 14:10:43 -0700 Cc: emc-p...@majordomo.ieee.org Message-Id: 2ff612b13481d311b40a009027b0c838bc8...@mail.packetcom.com X-Mailer: Internet Mail Service (5.5.2650.21) Received: by mail.packetcom.com with Internet Mail Service (5.5.2650.21) id SG87V1MD; Fri, 6 Oct 2000 14:10:52 -0700 from mail.packetcom.com (63.108.173.140) by smtp.c012.sfo.cp.net (209.228.13.148) with SMTP; 6 Oct 2000 14:06:06 -0700 by mail.packetcom.com with Internet Mail Service (5.5.2650.21) id SG87V1MD; Fri, 6 Oct 2000 14:10:52 -0700 Peter indicates that he is using this cap in an application up to 72 Vdc which is hazardous voltage according to UL 1950. Hazardous voltage must be separated from earth by at least basic insulation (clause 2.3.3.2). Regards, Scott Lemon Caspian Networks - RTP email: sle...@caspiannetworks.com phone: (919) 466-0315 fax: tbd -Original Message- From: Chris Collin [mailto:globalass...@altavista.com] Sent: Thursday, October 05, 2000 3:26 PM To: pmerguer...@itl.co.il Cc: emc-p...@majordomo.ieee.org Subject: Re: Suitability of X2 Capacitors as Basic Insulation Peter, I understand you want to use this capacitor between the Central Office battery and Ground (Protective Earth). Why do you need Basic Insulation anyway if you interconnect to Protective Earth. From my point of view, you only need Operational insulation. Regards, Chris Collin On Thu, 05 October 2000, Peter Merguerian wrote: Sender: owner-emc-p...@ieee.org X-Listname: emc-pstc To: emc-p...@majordomo.ieee.org Delivered-To: altavista.com%globalass...@altavista.com X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org X-Sender: itldom /pmerguerian@10.0.0.2 X-Resent-To: Multiple Recipients emc-p...@majordomo.ieee.org Received: by ruebert.ieee.org (8.9.3/8.9.3)id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) from ruebert.ieee.org (199.172.136.3) by smtp.c012.sfo.cp.net (209.228.13.220) with SMTP; 5 Oct 2000 03:44:44 -0700 by ruebert.ieee.org (8.9.3/8.9.3)id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) Content-Type: text/plain; charset=us-ascii Content-Length: 1102 X-Received: 5 Oct 2000 10:44:44 GMT Precedence: bulk Subject: Suitability of X2 Capacitors as Basic Insulation X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org [Un]Subscribe requests to majord...@majordomo.ieee.org From: Peter Merguerian pmerguer...@itl.co.il Return-Path: owner-emc-p...@ieee.org Mime-Version: 1.0 Reply-To: Peter Merguerian pmerguer...@itl.co.il Date: Thu, 05 Oct 2000 11:28:26 +0200 Message-Id: 3.0.6.32.20001005112826.00890790@10.0.0.2 X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.6 (32) Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message
RE: Suitability of X2 Capacitors as Basic Insulation
Peter indicates that he is using this cap in an application up to 72 Vdc which is hazardous voltage according to UL 1950. Hazardous voltage must be separated from earth by at least basic insulation (clause 2.3.3.2). Regards, Scott Lemon Caspian Networks - RTP email: sle...@caspiannetworks.com phone: (919) 466-0315 fax: tbd -Original Message- From: Chris Collin [mailto:globalass...@altavista.com] Sent: Thursday, October 05, 2000 3:26 PM To: pmerguer...@itl.co.il Cc: emc-p...@majordomo.ieee.org Subject: Re: Suitability of X2 Capacitors as Basic Insulation Peter, I understand you want to use this capacitor between the Central Office battery and Ground (Protective Earth). Why do you need Basic Insulation anyway if you interconnect to Protective Earth. From my point of view, you only need Operational insulation. Regards, Chris Collin On Thu, 05 October 2000, Peter Merguerian wrote: Sender: owner-emc-p...@ieee.org X-Listname: emc-pstc To: emc-p...@majordomo.ieee.org Delivered-To: altavista.com%globalass...@altavista.com X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org X-Sender: itldom /pmerguerian@10.0.0.2 X-Resent-To: Multiple Recipients emc-p...@majordomo.ieee.org Received: by ruebert.ieee.org (8.9.3/8.9.3)id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) from ruebert.ieee.org (199.172.136.3) by smtp.c012.sfo.cp.net (209.228.13.220) with SMTP; 5 Oct 2000 03:44:44 -0700 by ruebert.ieee.org (8.9.3/8.9.3) id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) Content-Type: text/plain; charset=us-ascii Content-Length: 1102 X-Received: 5 Oct 2000 10:44:44 GMT Precedence: bulk Subject: Suitability of X2 Capacitors as Basic Insulation X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org [Un]Subscribe requests to majord...@majordomo.ieee.org From: Peter Merguerian pmerguer...@itl.co.il Return-Path: owner-emc-p...@ieee.org Mime-Version: 1.0 Reply-To: Peter Merguerian pmerguer...@itl.co.il Date: Thu, 05 Oct 2000 11:28:26 +0200 Message-Id: 3.0.6.32.20001005112826.00890790@10.0.0.2 X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.6 (32) Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Re: Suitability of X2 Capacitors as Basic Insulation
Peter, I understand you want to use this capacitor between the Central Office battery and Ground (Protective Earth). Why do you need Basic Insulation anyway if you interconnect to Protective Earth. From my point of view, you only need Operational insulation. Regards, Chris Collin On Thu, 05 October 2000, Peter Merguerian wrote: Sender: owner-emc-p...@ieee.org X-Listname: emc-pstc To: emc-p...@majordomo.ieee.org Delivered-To: altavista.com%globalass...@altavista.com X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org X-Sender: itldom /pmerguerian@10.0.0.2 X-Resent-To: Multiple Recipients emc-p...@majordomo.ieee.org Received: by ruebert.ieee.org (8.9.3/8.9.3)id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) from ruebert.ieee.org (199.172.136.3) by smtp.c012.sfo.cp.net (209.228.13.220) with SMTP; 5 Oct 2000 03:44:44 -0700 by ruebert.ieee.org (8.9.3/8.9.3) id EAA17721; Thu, 5 Oct 2000 04:35:25 -0400 (EDT) Content-Type: text/plain; charset=us-ascii Content-Length: 1102 X-Received: 5 Oct 2000 10:44:44 GMT Precedence: bulk Subject: Suitability of X2 Capacitors as Basic Insulation X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org [Un]Subscribe requests to majord...@majordomo.ieee.org From: Peter Merguerian pmerguer...@itl.co.il Return-Path: owner-emc-p...@ieee.org Mime-Version: 1.0 Reply-To: Peter Merguerian pmerguer...@itl.co.il Date: Thu, 05 Oct 2000 11:28:26 +0200 Message-Id: 3.0.6.32.20001005112826.00890790@10.0.0.2 X-Mailer: QUALCOMM Windows Eudora Light Version 3.0.6 (32) Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org ___ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html ___ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Suitability of X2 Capacitors as Basic Insulation
Hello Peter: According to IEC 384-14, the capacitor types suitable to bridge BASIC INSULATION are Y2, Y3, or Y4 capacitors. According to the voltages you specify, a Y4 cap would be suitable. The thing to keep in mind here is clause 1.5.3 of IEC 384-14, which defined an X capacitor as: A capacitor...of a type suitable for use in situations where failure of the capacitor...WOULD NOT lead to danger of electric shock. Also, clause 1.5.1 of EN 60950 - Where safety is involved, components shall comply with either the requirements of this standard or with the safety aspects of the relevant IEC component standards. Based on your voltages, it appears that you are dealing with a DC distribuition system such as you would find in a Central Officeam I correct in assuming that this is TNV? (It could not be SELV as you are up to 72VDC). If so, then your question no doubt is embedded with concerns from clause 6.3.3 of EN 60950, UL 1950/CSA 950, etc. I have had conversations with various agencies on this issue in the past...some UL engineers I spoken with are of the opinion that any capacitor could be used in this situation so long as the equipment passes the Electric Strength test requirements. However, a number of labs in Europe insist on Y2 capacitors in this situation. My recomendation would be, assuming that my assumptions on the details of your application are correct: 1) Use at least a Y2 capacitor if the geographical area in which the equipment will be installed has a nominal mains supply voltage of greater than 150Vrms. 2) Use at least a Y4 capacitor if the geographical area in which the equipment will be installed has a nominal mains supply voltage of less than 150Vrms. Hope this helps... Regards, Mel mailto:mpeder...@midcom-inc.com -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Thursday, October 05, 2000 4:28 AM To: emc-p...@majordomo.ieee.org Subject: Suitability of X2 Capacitors as Basic Insulation Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org attachment: Mel_Pedersen_(vcard)_(E-mail).vcf
Suitability of X2 Capacitors as Basic Insulation
Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: 150VDC basic insulation versus 1000VAC test
Hello Moshe: It seems to me that your customer is too worried. I am assuming that you have your board layout designed for BASIC INSULATION between points the Telecommunications Network connection and points b) and c) of clause 6.4.2.2 of IEC 950. This is the requirement, and it will withstand a 1.0kV HY-POT. You should have 1.6mm of creepage and clearance between the network traces and the SELV traces. Points b) and c) should be SELV. With 1.6mm, you should be fine, as the breakdown for air is on the order of 3.0kV/mm. Assuming that you are talking about the ADSL line you refereed to earlier, another clause of IEC 950 may require a HY-POT test on the order of 1150V; Australia will require 1.5kV between the Network connection and points b) and c). Your board should pass at 1.5kV also. Norway and Sweden may require SUPPLEMENTARY INSULATION here rated for 250VDC between any circuit connected to Earth Ground and the Network, which is 2.5mm of spacing. That would also require a 1.5kV HY-POT test. If the above is not true, I will question my sanity. I do not think that you have anything to worry about. Make sure that your spacings are correct, and that you meet requirements for any components (transformers, capacitors, etc.) that might be bridging this barrier. Then you should be fine. Mel PedersenMidcom, Inc. Homologations Engineer Phone: (605) 882-8535 mpeder...@midcom-inc.com Fax: (605) 882-8633 -- From: mvald...@netvision.net.il[SMTP:mvald...@netvision.net.il] Sent: Thursday, August 06, 1998 2:10 AM To: emc-p...@ieee.org Subject:150VDC basic insulation versus 1000VAC test Hello everyone, My customer is having doubts about how a product designed for 150V pollution deg 2, CTI group 3, shall withstand the 1000V test (950 clause 6.4.2.2) It seems to me OK since the test is done for just one minute and very carefully. (And in a benign environment) Am I right to feel at ease about this? Should I add more separation between conductors (or other means) to make sure the product passes? regards, Moshe Name: moshe valdman E-mail: mvald...@netvision.net.il Phone: 972-52-941200 Telefax: 972-3-5496369 List-Post: emc-pstc@listserv.ieee.org Date: 6/8/98 Time: 0:10:05 You are most welcome to visit my homepage at: http://www.geocities.com/CapeCanaveral/5233/ - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.com with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, ri...@sdd.hp.com, or roger.volgst...@compaq.co (the list administrators).
Re: Basic insulation
Judd Stewart writes: We are currently designing an ac filter assembly. The board is extremely small and we need to put text in etch (copper) on board. About the only place is an area that provides basic insulation from ground. Judd: Would it be possible to provide your text in a (non conductive) silkscreen, instead of in copper? If your board uses silkscreen to show component outlines and reference designations, you can add the text to the silkscreen without compromising the insulation barrier. Joe Randolph
Re: Basic insulation
Hi Judd: We are currently designing an ac filter assembly. The board is extremely small and we need to put text in etch (copper) on board. About the only place is an area that provides basic insulation from ground. Essentially, the text in copper shorts out some of the basic insulation. Therefore, when measuring the creepage distance, you measure from one conductor to the nearest edge of the text, and then from the opposite edge of the text to the opposite conductor. If the sum of the two creepages equal or exceed the specified creepage, the text is okay. If not, then the design doesn't meet the creepage requirement. See IEC 950 or clone, Annex F, Figure F.15. The etched text is the intervening, unconnected conductive part. You might consider negative text in one of the larger conductors or in the ground conductor. Best regards from San Diego (North County Inland), Rich - Richard Nute Quality Department Hewlett-Packard Company Product Regulations Group San Diego Division (SDD) Tel : 619 655 3329 16399 West Bernardo Drive FAX : 619 655 4979 San Diego, California 92127 e-mail: ri...@sdd.hp.com -
Basic insulation
Hello from San Diego, My question deals with possible violation of the creepage distance in a primary circuit. We are currently designing an ac filter assembly. The board is extremely small and we need to put text in etch (copper) on board. About the only place is an area that provides basic insulation from ground. Do I have an issue here? Any help will be most appreciated. Thanks in advance Judd Stewart Litton Data System 619.623.6639
Results of basic insulation survey.
Hello from San Diego: A few weeks ago, I asked for anecdotes of failure of basic insulation after passing the production-line hi-pot test. Here is a summary of the responses. I've classified the failures into three broad classes, mechanical failures, thermal failures, and electrically- caused failures. MECHANICALLY-CAUSED FAILURES. PHYSICAL DAMAGE. Leads breaking through sheet insulator. Heat sink extrusion flaw penetrated insulation. Cord abrasion at sharp edges and strain-relief. Motor winding failure due to mechanical damage. Diode stud cut wire insulation. Cord insulation failure due to crush under furniture. Pinched between appliance inlet and metal frame. Magnet wire outside slot insulation. Caught in metal-to-metal joint. (Some of the physical damage incidents were manifested over time due to the cold flow of plastic material as a function of time. Initially, the insulation passed hi-pot, but failed at a later time.) BRIDGING. Bridged by leaking capacitor electrolyte (2 reports). Bridged by loose screw. Bridged by metal shavings (2 reports). THERMALLY-CAUSED FAILURES. Overheated components caused carbonized current paths. Overheated transformer caused insulation failure. Transformer thermal protector installed with shorted leads. Arcing in circuit-breaker heated the terminal insulation. ELECTRICALLY-CAUSED FAILURES. (No reports.) My motive in requesting this information was to determine whether or not the electric strength of basic insulation is adequate. A follow-on question is whether hi-pot testing is contributing to early failure of insulation. HP has studied the electric strength of insulation as a function of time and temperature in our optocouplers. The results of this study are published in the HP Optocoupler Application Note 1074. This note can be found on the web: http://www.hp.com/HP-COMP/isolator/app_index.html (This is an Adobe Acrobat file.) There is lots of circumstantial evidence to conclude: Hi-pot test voltage, hi-pot test waveform, and hi-pot test time are not critical to solid insulation or Y-capacitor lifetime. Electric strength requirements in safety standards are at least adequate, and may be quite conservative. The electric strength of modern insulating materials is very much greater than the electric strength required by safety standards. On the other hand, we don't do a good job of identifying mechanical threats to basic insulation. Best regards, Rich
Failure of BASIC insulation.
Hello from San Diego: I have been studying failures of basic insulation in electronic equipment. Basic insulation is the insulation that exists between mains (the primary circuit) and ground, or the first of the two insulations comprising double insulation. Basic insulation can be comprised of: Air insulation (clearance through air). Air-solid interface (creepage along the surface of insulation). Solid insulation. I have three sources of data: 1. Production-line hi-pot failure records. I have good data from this source. 2. Accelerated life test data. I have been performing some accelerated life tests on basic insulation. One failure. I will report on it in a follow-up message. 3. Field failure data. I have NO data whatsoever. I've never had a report of a failure of basic insulation in a production unit that passed the hi-pot test. This implies that basic insulation is extremely reliable. Are you aware of any such failure? If so, can you please send me the details? Please respond to me via e-mail. I will compile the results and report to this group. Thanks, and best regards, Rich - Richard Nute Quality Department Hewlett-Packard Company Product Regulations Group San Diego Division (SDD) Tel : 619 655 3329 16399 West Bernardo Drive FAX : 619 655 4979 San Diego, California 92127 e-mail: ri...@sdd.hp.com -
