Do you have the liberty to share your report - or details and results with
the group?
- Robert -
Robert A. Macy, PE m...@california.com
408 286 3985 fx 408 297 9121
AJM International Electronics Consultants
101 E San Fernando, Suite 402
San Jose, CA 95112
----- Original Message -----
From: "Spencer, David H" <david.spen...@usa.xerox.com>
To: <emc-p...@majordomo.ieee.org>
Sent: Wednesday, October 30, 2002 8:57 AM
Subject: RE: Measuring AC Line Impedance
>
> 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!
>
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