I read in !emc-pstc that Rich Nute <ri...@sdd.hp.com> wrote (in <200301281747.jaa29...@epgc264.sdd.hp.com>) about 'Unity Power Factor' on Tue, 28 Jan 2003: > > > > >Hi John: > > >> > No, this is not much of an issue for the U.S. (unless your facility is >> > actually affecting the utility); >> >> ... or frying the neutral conductors with third-harmonic current. > >In the USA, this has largely been fixed by a change in >the USA National Electrical Code.
There must be quite a number of installations that are not yet upgraded. > >When the load is largely electronic (off-line rectifiers) >the Code now requires a larger neutral conductor in three- >phase distributions. Yes, we do that in UK as well, for new installations. In some cases, the neutral, which is the same size as the phase conductors, is supplemented by another conductor, because the neutral current can, in an extreme case, exceed the phase current. > >Many constructions, while supplied from a three-phase source, >are wired as single-phase. So, in this case, the neutral >only carries the current of one phase, and we don't "fry" >the neutral. > That is a good solution. Are there any other problems appearing in the field which can be reliably determined as due to concentrations of non-linear loads of less than 3 kVA or so? -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! 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: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org 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
