I have been watching and reading this thread -- having spent nearly 15 years dealing with the harminics issue in ITE and in general.
There are many anecdotes out there about hte effect of harmonic currents on the electric supply. The on you cite is common. Distribution to cubicle areas was typically 3 phase with a common neutral. Triplen harmonics created high neutral current which overheated the electric connectors in the cubicle which led to the fires. As this developed, office partition manufacturers consulted with the Power Interface subcommittee of ITI, then CBEMA and shortly thereafter the problem was solved with larger neutrals or double neutrals and more robust connectors. Problems concerning harmonic currents in this country were solved by education. CBEMA wrote articles which wer picked up by trade publlications, sponsored, supported nd contributed to educational seminars such as those at the University of Wisconsin, Milwaukee. Most of the issues concerning harmonics are no longer issues, now that we understand harmonics are present, how to measure them and how to manage installations in their presence. The European harmonics standard IEC 61000-3-2, and I call it European because that is exactly what it is, is directed at protecting the public low voltage distribution system. All of these problems we have heard cited are those situations arising within facilities, NOT on the public distribution system. It is the power generating and transmission folks who drove this standard and largely ignored input of others. I make this comment based on considerable personal involvement since TC77A(Secr)36. John P. Wagner AVAYA Communication 1300 W. 120th Ave, Room B3-D16 Phone/Fax: (303) 538-4241 [email protected] > ---------- > From: Gary McInturff[SMTP:[email protected]] > Reply To: Gary McInturff > Sent: Tuesday, February 27, 2001 8:55 AM > To: 'John Juhasz'; 'Rich Nute'; [email protected] > Subject: RE: Harmonics -- WSJ opinion. > > Years ago when switch mode power supplies were really first being > introduced, we had a number of them installed in cubicles in a new > building. We were the first occupants. We started having a rash of > fires that were starting in the outlet receptacles in the cubicles. > The building management teams went looking for the causes and we found > no imbalance in the power distribution etc. The world looked good to > them. Still the fires continued (quickly extinguished at the source > mind you so they never spread) but it was observed that those offices > that were have a problem all had the equipment with the switch mode > supplies, and we quickly shuffled those around and the fires quit. > Neither the building engineers or we EE's had any clue about > harmonics on problems with these so that wasn't looked at and I can't > say for certain that was the reason, but after shifting the load of > the switch mode supplies around on different branch circuits the > problem stopped. So I certainly have my suspicions. > Gary > > -----Original Message[Gary McInturff] ut ----- > From: John Juhasz [mailto:[email protected]] > Sent: Monday, February 26, 2001 10:37 AM > To: 'Rich Nute'; [email protected] > Subject: RE: Harmonics -- WSJ opinion. > > > > Rich, > > I would think that you knew that this would generate discussion? > > > One comment of Mr Hunter's that stood out in particular was the > very last . . . > " . . . the only ones who benefit from the harmonic current > emission standard > are the European electricity distributors. They "avoid > investments in bolstering their networks against the > theoretical harmonics risk" at the cost of manufacturers > and consumers." > > I would say that this senitment has been echoed by many > compliance engineers. > But the comment is 'non-technical' . . . can anyone in this > forum offer > any 'technical' arguments that would a)Back-up such a statement > as > Mr. Hunter's or b) FAVOR the harmonic standard? > > I like to give the benefit of the doubt that the standard was > created based > on sound technical evidence. > > John Juhasz > Fiber Options > Bohemia, NY > > -----Original Message----- > From: Rich Nute [ <mailto:[email protected]>] > Sent: Monday, February 26, 2001 12:11 PM > To: [email protected] > Subject: Harmonics -- WSJ opinion. > > > With thanks to Ed Jones... > > On Thusday, February 22, The Wall Street Journal Europe > published an interesting opinion on the harmonic current > emissions standard. > > The opinion is by Rob Hunter, a lawyer and Chairman of > the Centre for the New Europe, a Brussels-based think > tank. > > Mr. Hunter is quite critical of the EU "New Approach" > process. He says: > > "In this procedure, the EU sets vague safety and > technical rules for everything from toys to super- > computers -- for example, toys shall be 'safe.' The > EU then delegates to private standardization bodies > the drafting of detailed requirements explaining > what the delphic rules mean." > > "The supposed advantage of this New Approach is > twofold. For industry, it gets to write the detailed > rules applying to it. For the Commission, the New > Approach frees it from a burdenom task; it also > allows the Commission to claim that it has nothing to > do with writing the standards, and hence cannot be > held responsible." > > "All this sounds quite above-board. It isn't." > > "For one thing, the standards are not merelay a means > of proving compliance with the underlying legislation. > They actually determine the meaning of the law itself." > > Mr. Hunter discusses "...the way these standard-setting > bodies can be gamed by industry insiders for advantage." > > Mr. Hunter goes on to show how the New Approach process > allows the Commission to sidestep "...WTO laws prohibiting > 'mandatory' product measures that create 'unnecessary > obstacles' to international trade." > > Mr. Hunter's opinion goes on to show that the only ones > who benefit from the harmonic current emission standard > are the European electricity distributors. They "avoid > investments in bolstering their networks against the > theoretical harmonics risk" at the cost of manufacturers > and consumers. > > > Best regards, > Rich > > > > > > > > ------------------------------------------- > 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: > Michael Garretson: [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.rcic.com/> click on "Virtual Conference > Hall," > >
