RE: isolation of battery (72V max) input
Dear Edward and Moshe, The EN60950 standard allows you various options for compliance with insulation between the max 72 Vdc source of supply (considered a hazardous secondary circuit) and SELV. One way to comply is reinfoced insulation as Edward has stated. But based on the many products which we have tested in our labs, we find that this providing reinforced insulation is not a practical solution for most clients. In many cases, our clients do not have insulation at all. In this case, the standard allows you to interconnect hazardous secondary circuits and SELV if abnormals are done (shorting or opening of components or circuits) to detrmine that the SELV limits are not exceeded. Remember that for some countries (Australia and Germany), CO's recognize the max 72 Vdc supply as a TNV-2 circuit. As such for these countries where the CO supply voltage can reach up to 72 Vdc, you may wish to comply with the TNV-2 to SELV limits specified in my previous e-mail. For most other countries, the CO supply voltage is earthed SELV and does not exceed 60 Vdc. For these countries you may wish to comply with the SELV to SELV or operational insulation requirements. Regards, Date sent: Thu, 22 Oct 1998 14:47:40 -0400 From: Edward Eszlari e_eszl...@compuserve.com Subject:RE: isolation of battery (72V max) input To: INTERNET:mvald...@netvision.net.il mvald...@netvision.net.il, t...@world.std.com, emc-p...@ieee.org Send reply to: Edward Eszlari e_eszl...@compuserve.com Moshe, The answer to your question is Reinforced insulation for the working voltage measured in that location. The 72V supply is considered hazardous voltage and if an SELV circuit is present on conductors nearby, this is the type of insulation system that is required. If this CO like enviroment can be considered a Restricted Access Area per 2.1.4.2 (EN60950), or Service Access Area per 2.1.4.1, lesser requirements may apply. Also consider if this SELV circuit does not need to be classified as SELV (no operator access), you may be able to get away with no insulation, but other requirements may apply depending on how this system is set-up. Regards, Edward Eszlari TUV Rheinland of N.A., Inc. Marlborough, MA 508-460-0792 - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
RE: isolation of battery (72V max) input
Moshe, The answer to your question is Reinforced insulation for the working voltage measured in that location. The 72V supply is considered hazardous voltage and if an SELV circuit is present on conductors nearby, this is the type of insulation system that is required. If this CO like enviroment can be considered a Restricted Access Area per 2.1.4.2 (EN60950), or Service Access Area per 2.1.4.1, lesser requirements may apply. Also consider if this SELV circuit does not need to be classified as SELV (no operator access), you may be able to get away with no insulation, but other requirements may apply depending on how this system is set-up. Regards, Edward Eszlari TUV Rheinland of N.A., Inc. Marlborough, MA 508-460-0792
RE: isolation of battery (72V max) input
Moshe: We treat the 48V input as a secondary voltage with primary voltage rules. Therefore, you will have to hold to the _reinforced_ distances for creepage and clearance. Regards, John R. Kretsch, P.E. Compliance Engineering Supervisor ADC Broadband Communications john_kret...@adc.com -Original Message- From: mvald...@netvision.net.il [mailto:mvald...@netvision.net.il] Sent: Wednesday, October 21, 1998 03:44 To: emc-p...@ieee.org; t...@world.std.com Subject: isolation of battery (72V max) input Hello everyone, What are creepage/clearance requirements between battery (60V nominal which could go to 72V) conductors and SELV conductors? The equipment resides in CO like environment. thanks in advance, 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: 21/10/98 Time: 0:44:10 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.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: isolation of battery (72V max) input from SELV Circuits
Dear Moshe, I assume you mean creepages and clearances between input circuits and SELV circuits (and not conductors). I am also assuming you are familiar with the clearance and creepage Tables in UL1950 and/or EN 60950 which depends on the Installation Category and Pollution Degree. In regards to insulation for North America, because of limitations on TNV circuits, a max 72 Vdc supply is considered a secondary hazardous circuit. If you do not have the required insulation between these circuits (basic or reinforced insulation depending on whether circuits are reliably earthed or not), the standard allows you to interconnect the two circuits if abnormals are done between components in the two circuits and you still maintain the criteria for SELV voltage limits. Regret I cannot reference the claues at this time since I am at home and not in our laboratories. For Europe, the max 72 Vdc supply circuit can be considered a TNV-2 circuit if not subject to overvoltages. In this case, between a TNV-2 circuit and SELV, you need to comply with the basic insulation requirements and also the Dielectric Sterngth or Impulse Test requirements (again I do not have the standard to give you details). I suggest for worldwide Approvals, you consider the strictest of the above specified requirements. Although you have not asked, do not forget that in the US, a means for connection to the supply is needed in accordance to the NEC, such as a field wiring compartment with terminal blocks or min 6 inch pigtail leads. A compartment (with knockouts or holes for field wiring) is not needed for equipment to be Recognized or which is intended for Restricted Access Locations (RAL). In the latter case, instructions are needed for routing of the field wiring so that they are not damaged during installation and normal use of your equipment. Hope this helps. Best Regards, From: mvald...@netvision.net.il Date sent: Wed, 21 Oct 98 00:44:09 PDT Subject:isolation of battery (72V max) input To: emc-p...@ieee.org, t...@world.std.com Send reply to: mvald...@netvision.net.il Hello everyone, What are creepage/clearance requirements between battery (60V nominal which could go to 72V) conductors and SELV conductors? The equipment resides in CO like environment. thanks in advance, Moshe Name: moshe valdman E-mail: mvald...@netvision.net.il Phone: 972-52-941200 Telefax: 972-3-5496369 Date: 21/10/98 Time: 0:44:10 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.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
(Fwd) Re: isolation of battery (72V max) input from SELV Circu
--- Forwarded Message Follows --- From: Self Single-user mode To: emc-p...@ieee.org, t...@world.std.com, mvald...@netvision.net.il Subject:Re: isolation of battery (72V max) input from SELV Circuits Date sent: Wed, 21 Oct 1998 23:11:48 +0200 Dear Moshe, I assume you mean creepages and clearances between input circuits and SELV circuits (and not conductors). I am also assuming you are familiar with the clearance and creepage Tables in UL1950 and/or EN 60950 which depends on the Installation Category and Pollution Degree. In regards to insulation for North America, because of limitations on TNV circuits, a max 72 Vdc supply is considered a secondary hazardous circuit. If you do not have the required insulation between these circuits (basic or reinforced insulation depending on whether circuits are reliably earthed or not), the standard allows you to interconnect the two circuits if abnormals are done between components in the two circuits and you still maintain the criteria for SELV voltage limits. Regret I cannot reference the claues at this time since I am at home and not in our laboratories. For Europe, the max 72 Vdc supply circuit can be considered a TNV-2 circuit if not subject to overvoltages. In this case, between a TNV-2 circuit and SELV, you need to comply with the basic insulation requirements and also the Dielectric Sterngth or Impulse Test requirements (again I do not have the standard to give you details). I suggest for worldwide Approvals, you consider the strictest of the above specified requirements. Although you have not asked, do not forget that in the US, a means for connection to the supply is needed in accordance to the NEC, such as a field wiring compartment with terminal blocks or min 6 inch pigtail leads. A compartment (with knockouts or holes for field wiring) is not needed for equipment to be Recognized or which is intended for Restricted Access Locations (RAL). In the latter case, instructions are needed for routing of the field wiring so that they are not damaged during installation and normal use of your equipment. Hope this helps. Best Regards, From: mvald...@netvision.net.il Date sent: Wed, 21 Oct 98 00:44:09 PDT Subject:isolation of battery (72V max) input To: emc-p...@ieee.org, t...@world.std.com Send reply to: mvald...@netvision.net.il Hello everyone, What are creepage/clearance requirements between battery (60V nominal which could go to 72V) conductors and SELV conductors? The equipment resides in CO like environment. thanks in advance, Moshe Name: moshe valdman E-mail: mvald...@netvision.net.il Phone: 972-52-941200 Telefax: 972-3-5496369 Date: 21/10/98 Time: 0:44:10 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.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators). - This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: unsubscribe emc-pstc (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
