Follow up............................ Having just completed an ton of work on this using input I got around here (thanks to Don Borowski, Patrick Lawler, Joe Randolph and John Woodgate). I believe we have characterized the AC mains of our facility.
As a sanity check/ technical check can any one comment on process. Part one 1)Open circuit voltage measured. 2)Resistive load placed in circuit. 3) Voltage drop and current measured. 4) Voltage drop divided by current provides resistance component of AC mains. Part 2 1) Open circuit voltage measured. 2)Reactive load placed in circuit (approximately 120uF!) 3) Voltage change (increase really) and current measured (phase angle was recorded to back check math vectorialy). 4) Voltage change divided by current provides reactive component of AC mains. As a side note, I also connected an isolation transformer as the reactive load, the reactive numbers were very very close. The resistive number + reactive number then make up the AC line impedance for this site: Ztest if you will. My two remaining questions: Is this method of characterizing the AC line impedance valid (is there something I'm missing)? Based on my knowledge of these values, and their ratio to the reference impedance(s) specified in EN61000-3-3 and EN61000-3-11, I should be able to calculate and correlate the measured Dmax, Pst, et. al...to the limits specified in those standards. (REFERENCE section 6.1.3 of EN61000-3-11), using our existing AC mains. Any comments or input would be welcome. Thanks Regards David Spencer Xerox Corp. -----Original Message----- From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, September 19, 2002 11:56 AM To: emc-p...@majordomo.ieee.org Subject: Re: Measuring AC Line Impedance I read in !emc-pstc that Spencer, David H <david.spen...@usa.xerox.com> wrote (in <052106A55179D611B34300096BB02E3F8B1D@USAMCMS4>) about 'Measuring AC Line Impedance' on Thu, 19 Sep 2002: >Is anyone familiar with a method to measure and calculate those values. The >generic values I have for short circuit condition (which include 4 wires in >a magnetic conduit) come out higher than my measured values, and those do >not include the motor generator source. Put a large capacitor (mains voltage rated) across the mains and measure the voltage change; it may actually increase. You need about 50 uF to get a decent change on 120 V 60 Hz mains. With that result and the one with the resistive load, you can calculate the source impedance as an R and L in series. I'd be interested to learn the result. -- Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk Interested in professional sound reinforcement and distribution? Then go to http://www.isce.org.uk PLEASE do NOT copy news posts to me by E-MAIL! ------------------------------------------- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com 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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- 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: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com 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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
