------- 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).
