I also learned, that there is a three-phase delta system in USA with 500 Vac per phase. One phase (L3) is earthed.
Is this system very often used in USA? Is it correct information, that L3 is always earthed and not L1 or L2. Horst Haug -----Ursprüngliche Nachricht----- Von: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]Im Auftrag von Crabb, John Gesendet: Montag, 17. Dezember 2001 11:28 An: 'Bill Lawrence'; 'EMC-PSTC Forum' Betreff: RE: 2 Phases in North America Bill - you absolutely correct in describing the North American system as "single-phase, 3 wire". After all, that is how it is described in Annex V, Figure V.4 of IEC60950:1999 - and there is NO WAY that IEC TC74 could be wrong, is there ? (especially since the US committee must have voted yes, to include this change, the purpose of which was to educate those of us who weren't too clear on the subject). Fortunately I am on holiday (vacation) from tonight until January 3, so to all our readers, best wishes for the Christmas season, and a happy and prosperous 2002. John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :john.cr...@scotland.ncr.com Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289. -----Original Message----- From: Bill Lawrence [mailto:wlawr...@capecod.net] Sent: 14 December 2001 22:33 To: 'Wagner, John P (John)'; 'Robert Johnson'; 'Cortland Richmond' Cc: 'Barry Esmore'; 'EMC-PSTC Forum' Subject: RE: 2 Phases in North America Two Phase / 5 Wire (4 "hots" and a neutral) was a common power distribution in US cities in the early part of this century. Many early motors are "2-phase" motors. I learned about this when helping with connection of these motors to run on a 3 phase power system via a special "Scott-T" transformer connection. The correct designation for the 120/240 power system described is "Single Phase / 3 Wire". Bill Lawrence
