Richard, I recognize that system. It is a 3 phase delta with one of the sides tapped in the middle for the neutral. I haven't seen one since the late 50's, and then only in the oldest sections of downtown Houston. The scheme provided 3 phase service to AC compressors and air handlers, and also supplied 110 volts for lighting and office equipment.
The 208 phase you found was then known as the "wild phase" or the "stinger leg". It was about 190 volts when the phase to phase voltage was 220. The relationship to 240 does work out; 190 X (240/220) = 207; nearly what you found. If you look outside the building you should be able to see the transformer connections to confirm this. I had almost forgotten such a thing ever existed. Lou Aiken, LaMer LLC 27109 Palmetto Drive Orange Beach, AL 36561 USA tel ++ 1 251 981 6786 fax ++ 1 251 981 3054 Cell ++ 1 251 979 4648 From: Richard Meyette <[email protected]> To: <[email protected]> Sent: Thursday, June 05, 2003 6:51 PM 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 > 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
