In an attempt to apply a real application to the topic of harmonic emissions, lets take the example of a 30-50 amp single phase precision high temperature furnace in a piece of analytical test equipment (>1000ºC). The control method of choice would be phase control to precisely control the temperature and extend the life of the heating elements. Unfortunately this method generates harmonic emissions. Zero crossing control method would have problems with Flicker Emissions and would shorten heating element life. What other “practical” furnace control methods are there that would pass both the Harmonics and flicker emissions requirements? From my research, phase control is the method used on like equipment, but how do they get around the harmonic issue?
The Harmonic and Flicker emissions standards are only for equipment used on a “Public Low-Voltage Distribution Network”. How common is it that professional equipment such as described above would be used on a Public network in Europe? Thanks to all. I’m learning a lot. The Other Brian From: [email protected] [mailto:[email protected]] On Behalf Of John M Woodgate Sent: Monday, April 26, 2010 8:31 AM To: [email protected] Subject: Re: [PSES] Harmonic Emissions Testing In message <16641305538561692815456@IMAC8632>, Jon Francis <[email protected]> writes >My understanding (happy to be corrected) of the reasons for harmonic >current control are: > >1/ Limiting voltage distortion > >2/ Limiting apparent power requirements. >Since transmission and generating capacity is rated in VA (kVA >transformers, Isquared R losses in lines) rather than watts, then >harmonic current that contributes to VA but not to Watts requires >increased utility capacity for no extra true power delivered. I have several times suggested 2/ as a reason; the I^2R losses represent an economic loss to the industry, but the supply industry experts say it is not a significant issue. It is significant at the product level if the poor power factor results in a current exceeding common wall-socket ratings. -- 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]> _________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - 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]>
