Re: Harmonics measurement instrumentation - solved !
The situation with the two setups for harmonic measurement was solved, and the problem was quite simple ... The resistance of the cables used with the watt meter was 0.25 ohms . Enough to reduce the harmonics sufficiently. Not using the appropriate cables was a basic mistake... but I am happy to have learned another detail that makes difference in an EMC test. Thanks for all that replied my mail. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. "Robert Macy" To: , Sent by: cc: owner-emc-pstc@majordoSubject: Re: Harmonics measurement instrumentation mo.ieee.org 22/01/02 18:06 Please respond to "Robert Macy" Hmmm...measured with a current meter, then measured with a wattmeter and got different answersHarmonics out of phase? contain no power? - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: gunter_j_ma...@embraco.com.br To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, January 22, 2002 11:56 AM Subject: Harmonics measurement instrumentation List I would like your precious opinion about a situation regarding harmonic current measurement (61000-3-2). First case: Using a sinusoidal AC power source, with a controlled output voltage (almost perfect sine, voltage THD lower than the needed, even with load), I measured the current harmonics using the internal instrument of the power source. The 13th and 15th harmonics were right above the limits (Class A limits). Second case: I add a digital wattimeter to measure the harmonics. The harmonic content became 30% lower than the first case (good enough to pass). And I got this results with the two instruments (the one inside the power source, and the wattimeter). My first thought was the increased impedance due to the wattimeter (Zm). But I got 50mV of drop voltage in this instrument (peak voltage), that is lower than the specified in 61000-3-2, Annex B (0,15Vpeak maximum). And the impedance of its current shunt is only 0,008 ohms (data from its manual). This put my first guess down ! Theoretically, the wattimeter couldn't attenuate so much the harmonics ! Any idea of what could be happening ? Thank you again. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- This message is from the IEEE EMC Society Product Safety Technical Comm
Re: Harmonics measurement instrumentation
Hmmm...measured with a current meter, then measured with a wattmeter and got different answersHarmonics out of phase? contain no power? - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: gunter_j_ma...@embraco.com.br To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Tuesday, January 22, 2002 11:56 AM Subject: Harmonics measurement instrumentation List I would like your precious opinion about a situation regarding harmonic current measurement (61000-3-2). First case: Using a sinusoidal AC power source, with a controlled output voltage (almost perfect sine, voltage THD lower than the needed, even with load), I measured the current harmonics using the internal instrument of the power source. The 13th and 15th harmonics were right above the limits (Class A limits). Second case: I add a digital wattimeter to measure the harmonics. The harmonic content became 30% lower than the first case (good enough to pass). And I got this results with the two instruments (the one inside the power source, and the wattimeter). My first thought was the increased impedance due to the wattimeter (Zm). But I got 50mV of drop voltage in this instrument (peak voltage), that is lower than the specified in 61000-3-2, Annex B (0,15Vpeak maximum). And the impedance of its current shunt is only 0,008 ohms (data from its manual). This put my first guess down ! Theoretically, the wattimeter couldn't attenuate so much the harmonics ! Any idea of what could be happening ? Thank you again. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
Harmonics measurement instrumentation
List I would like your precious opinion about a situation regarding harmonic current measurement (61000-3-2). First case: Using a sinusoidal AC power source, with a controlled output voltage (almost perfect sine, voltage THD lower than the needed, even with load), I measured the current harmonics using the internal instrument of the power source. The 13th and 15th harmonics were right above the limits (Class A limits). Second case: I add a digital wattimeter to measure the harmonics. The harmonic content became 30% lower than the first case (good enough to pass). And I got this results with the two instruments (the one inside the power source, and the wattimeter). My first thought was the increased impedance due to the wattimeter (Zm). But I got 50mV of drop voltage in this instrument (peak voltage), that is lower than the specified in 61000-3-2, Annex B (0,15Vpeak maximum). And the impedance of its current shunt is only 0,008 ohms (data from its manual). This put my first guess down ! Theoretically, the wattimeter couldn't attenuate so much the harmonics ! Any idea of what could be happening ? Thank you again. Günter J. Maass Researcher - Power Electronics Development EMBRACO S.A. --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.