RE: UL1950/EN 60 950 Spacings
Peter, We have the same situation with my company's products. We use the nominal line to neutral voltage even when no neutral is present. Our experience has been that the certifying agencies accept this. Best Regards, Jeff Jenkins Senior Regulatory Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, CO USA Opinions are my own, etc. -Original Message- From: pe...@itl.co.il [mailto:pe...@itl.co.il] Sent: Tuesday, July 06, 1999 1:57 PM To: emc-p...@ieee.org Cc: al...@itl.co.il; ico...@itl.co.il; zoh...@itl.co.il; plei...@itl.co.il; sgn...@itl.co.il Subject: UL1950/EN 60 950 Spacings Dear All, The subject standards specify that Tables 3, 4, 5 (clearances) are based on nominal line to neutral supply voltages. For equipment powered by 3 phase (L1,L2,L3 and earth) WITHOUT a neutral, how should the nominal supply voltage be treated? Regards, Peter PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: pe...@itl.co.il Visit our Website: http://www.itl.co.il - 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, jim_bac...@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, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
Re: UL1950/EN 60 950 Spacings
Dear Peter, IEC 950 Second edition A4, 1996, is available to me. You can read in 2.9.1 on page 105A in the second paragraph: For all POWER SYSTEMS, the mains supply voltage in tables 3, 4 and 5 is the phase-to-neutral voltage. To discuss your case where you do not supply the neutral to your equipment, here are some explanations: Since tables 3, 4 and 5 are concerned with Clearances, the mayor contributor to the spacing requirements are the transients. Investigations in old days have shown that the transients are roughly the same on all 3 phases L1, L2 and L3 of a three-phase distribution system. Transients are categorized into Overvoltage Categories in IEC 664-1 table 1. There are other hints given to IEC 364-4-443 and IEC 38. If you follow all through this jungle you will end up with a simple equation: If you operate your equipment in Overvoltage Category II from a single phase 230 V r.m.s. or from three phases 400 V r.m.s. supply system with or without neutral connected to the equipment, you have to consider transients of 2500 V. This is the determining value for your clearance. Back to IEC 950 table 3 your insulation working voltage is up to 300 V r.m.s. in the above mentioned example, and you have found the needed row for the required clearances. Kind regards/mit freundlichen Gruessen Horst Dierich -- Peter Merguerian wrote: Dear All, The subject standards specify that Tables 3, 4, 5 (clearances) are based on nominal line to neutral supply voltages. For equipment powered by 3 phase (L1,L2,L3 and earth) WITHOUT a neutral, how should the nominal supply voltage be treated? Regards, Peter PETER S. MERGUERIAN MANAGING DIRECTOR PRODUCT TESTING DIVISION I.T.L. (PRODUCT TESTING) LTD. HACHAROSHET 26, P.O.B. 211 OR YEHUDA 60251, ISRAEL TEL: 972-3-5339022 FAX: 972-3-5339019 E-MAIL: pe...@itl.co.il Visit our Website: http://www.itl.co.il - 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, jim_bac...@monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
