http://www.ieee-pses.org/symposium http://www.emc2004.org/
Robert This is exactly what I was looking for. It fits the results of the measurements that were made. Thank you very much. John From: Robert Johnson [mailto:[email protected]] Sent: 26 July 2004 14:44 To: [email protected]; 'EMC-PSTC (E-mail)' Subject: RE: Three Phase Power in Belize The world power description tables (see http://www.safetylink.com/)are not much help on three phase. What you describe sounds like a three phase center grounded delta supply. Belize standard voltages are 100/220V 60 Hz. I'll assume 120/240V for your case. That means a center tap on one leg of the delta is grounded. This provides 120v from neutral to phase A and 120 volt neutral to phase B, with 240V phase A to B (conventional household supplies) The third phase, C, is 240 volts from A or B and 208 volts from neutral (thus the term high line). Often the supply is done with only two transformers, omitting a supply transformer for phase A-C to save costs but with reduced power and slightly less balanced phase voltages (you can ignore that fact). This means you actually have a 240 volt three phase supply, not a 208 volt one. Let's see if I can draw a crude text vector diagram. C /|\ / | \ / | \ / | \ / | \ / | \ 240 208 240 / | \ / | \ A---120---N---120---B -------240------- Keep in mind, the info you provided is not near enough to assure a match with what I described above. In any case, if you have three phases 240 volts apart, you can simply connect delta loads wired for 240 without much worry. Likewise for 208 volts. Bob Johnson ITE Safety From: [email protected] [mailto:[email protected]] On Behalf Of John McAuley Sent: Monday, July 26, 2004 6:45 AM To: EMC-PSTC (E-mail) Subject: Three Phase Power in Belize http://www.ieee-pses.org/symposium http://www.emc2004.org/ Dear Group A friend of mine is doing development/charity work in Belize and is trying to hook up some old lathes, milling machines etc of European origin to their supply. He has limited electrical knowledge being from a mechanical background. He tells me that the supply is "high line". Apparently this means that they have two phases at 120 V and a third line at 208 V!! Apparently there are 3 phase machines already running on this supply. He has measured the phase voltages and has confirmed the levels. The machines were rewired for a 120V/208V system. Is anyone familiar with this connection system? Is there a voltage offset on the neutral? I can't find reference to it on the internet. I would like to be in a position to teach him how the identify the phase voltages so that he can connect up the machines without generating any more smoke. Many Thanks John McAuley This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [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: http://www.ieeecommunities.org/emc-pstc This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. IEEE PSES Main Website: http://www.ieee-pses.org/ To post a message send your e-mail to [email protected] Instructions for use of the list server: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Ron Pickard: [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: http://www.ieeecommunities.org/emc-pstc
