RE: 2 Phases in North AmericaTwo 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 -----Original Message----- From: [email protected] [mailto:[email protected]]On Behalf Of Wagner, John P (John) Sent: Friday, December 14, 2001 3:14 PM To: Robert Johnson; Cortland Richmond Cc: Barry Esmore; EMC-PSTC Forum Subject: RE: 2 Phases in North America Actually, 2 phase systems have a phase rotation of 90 degrees, not 180. Two phase systems have been used for control motors and the like, but are fairly rare these days. 180 degree rotation between "phases" is a center tapped single phase system. The proper terminology is, I believe, split phase. John P. Wagner Regulatory Compliance & Mandatory Standards AVAYA Strategic Standards. 1300 W. 120th Ave, Room B3-D16 Phone/Fax: (303) 538-4241 [email protected] ---------- From: Cortland Richmond[SMTP:[email protected]] Reply To: Cortland Richmond Sent: Friday, December 14, 2001 10:38 AM To: Robert Johnson Cc: 'Barry Esmore'; 'EMC-PSTC Forum' Subject: Re: 2 Phases in North America By the definition below, *single phase* AC would require one wire with no return. I want to see THAT one work before I pay for it! Cortland Richmond (the above being my own opinion, not a statement of my employer's) Robert Johnson wrote: This has just reopened the old two phase controversy again. Ed has done a good job of describing the systems in detail, but be careful with the terms. Ask an electrical engineer about a 120/240 volt home service and he will call it a two phase system. Two phases 180 degrees out of phase is technically correct. ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
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