We do have problems with mains harmonic currents in 120/240V, 3-wire distribution system and there are harmonic emission limits for grid-tie inverters connecting to the public utility at low voltage.
Ralph McDiarmid, AScT Compliance Engineering Group Xantrex Technology Inc. www.xantrex.com From: [email protected] [mailto:[email protected]] On Behalf Of John M Woodgate Sent: Wednesday, May 20, 2009 6:49 PM To: [email protected] Subject: Re: IEC 60950-1 short circuit test criteria In message <17F4541E55F74F6AACBF9107A0A2A9B7@Pete97219Compaq>, Pete Perkins <[email protected]> writes > In the North American distribution system the short circuit current >that can be expected from the usual 115V domestic & commercial outlet >is on the order of 7000A. ... which is why you don't have the problems with mains harmonic currents that we do in Europe - your typical mains impedance is far lower. Ours is about half an ohm at the point where the utility wiring meets the house wiring. So the prospective short-circuit current is only about 460 A. Even so, ordinary fuses are inadequate (breaking capacity around 100 A - they explode with a real short-circuit), so we use 'enhanced breaking capacity' or 'high breaking capacity' types. -- This is my travelling signature, adding no superfluous mass. John M Woodgate - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
