In message <FCA549BE3ECF9D4CB8CB8576837EA4890A7259@ZEUS.cetest.local>, "ce-test, qualified testing bv - Gert Gremmen" <g.grem...@cetest.nl> writes > > >I have personally been involved in measuring > >over 40 amps of neutral conductor (@150 Hz) current > >in a building stuffed with ITE equipment, > >where only 10-16 A rms per phase was > >measured. The neutral conductor was a > >1.5 mm2 wire, and the phase conductors > >were 2.5 mm2 > > > >So I assure you that harmonics can be hazardous if ignored.
Yes: the neutral current can exceed 208 times the phase current in a 3-phse system feeding only SMPS without power factor correction. > > > >To John: > >? Limiting apparent power requirements? > >Right and ?harmonics current? is another way of saying that. > > > >? the I^2R losses represent an economic loss to the industry, but the >supply industry experts say it is not a significant issue? > > > >But I personally would be more than happy getting paid the >insignificant amount of > >money lost by I^2R losses !!! ;<)) Agreed. > > > >A IGBT costing less than 5 dollars per phase is able to control > >a load of 10 kW easily at say 5 or 10 kHz. > >It is not even difficult to have a power factor of 1 with the right > >Topology. You will need large inductors to smooth out > >the switching frequency or active power factor correction > >circuits that at a nominal current level of 10-20% of the > >mains current to be corrected, are able to smooth all > >current irregularities, so a pure sinus current in phase > >with the mains is consumed. > >The power loss is about 0.5 % of the corrected power stream > >as the injected current is out of phase in the opposite way > >as the harmonics of the main power stream, and as these > >devices are also switched, and have an efficiency of > >90% or better. Products like that are already on the market. But some other products don't have an economic technology that eliminates harmonic emissions. -- 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 <emc-p...@ieee.org> 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 <emcp...@socal.rr.com> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
