Others have correctly identified the typical configuration. This can also be generated by an open delta (two transformers). This is sometimes used to provide three phase service to a small business customer with only one or two three phase loads. You start with the customary 120/240 single phase center tapped service, and with only one more transformer you add the third leg with a 240 volt winding (you need the three primary phases to begin with). It's a cheap solution with lower efficiency, but it works.
Bob Johnson ITE Safety From: [email protected] [mailto:[email protected]] On Behalf Of Richard Meyette Sent: Thursday, June 05, 2003 7:52 PM To: [email protected] Subject: 3-Phase Power Question Here's a question for the power engineers in the group. I measured the following phase voltages for the 3-phase power lines feeding a breaker box: phase to phase (all three phases) = 240V phase to neutral (2 of 3 phases) = 120V phase to neutral (1 of 3 phases) = 208V Normally you would expect the phase to phase voltages to measure 208V and the phase to neutral voltages to measure 120V for a Y-connected transformer. What kind of power transformer configuration would provide these phase voltages? Thanks in advance to anyone who can shed some light on this, Richard Meyette [email protected] 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: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] Archive is being moved, we will announce when it is back on-line. All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
