Keep in mind a couple special conditions: In some medical areas like operating rooms isolating transformers are used, in which case normal operation is a balanced 60 volts to ground from either phase or neutral. IT systems are often similar. In either case, faults will place either neutral or phase at the phase voltage above ground and permit continued operation. In some recording studios systems a 120 volt supply with a center tap neutral is provided for hum reduction. On a three phase IT system, a fault may end up with both conductors of a single phase load at phase voltage above ground. Miswiring, swapping phase and neutral is also common. Equipment for 230 volt is sometimes run in North America on 208 volts (of a 120/208 volt 3 phase supply), each leg being 120 volts to ground. The message is, assume the neutral may be up to phase voltage above ground.
Bob Scott Douglas wrote: > I have a question about what is an acceptable voltage range for voltage > measured between the Neutral line and the Earth line in both the USA and > in Europe. I am concerned strictly with 115 and 230 VAC systems for ITE. > > I know that in the USA we measure from Hot to Earth and get approx. 115 > VAC and we measure between the Neutral and Earth and get something less > than 10 VAC. > > As far as I can tell, if you measure from Hot to Earth in Europe you get > approx. 230 VAC and from Neutral to Earth you get less than 10 VAC. I also > know that you may not have an Earth terminal in some places in Europe or > that it can be something not Earth. > > I should (and think I do) know the answer to this. But I would like to > hear from others. Thanks in advance for your replies. > > Regards, > Scott > s_doug...@ecrm.com --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to majord...@ieee.org with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to ed.pr...@cubic.com, j...@gwmail.monarch.com, ri...@sdd.hp.com, or roger.volgst...@compaq.com (the list administrators).
