[RE-wrenches] Megometers

[Phil Undercuffler]

Nick,

If the voltage bleeds away when you connect your meter, you're seeing a
capacitive charge that accumulates by things like wind blowing across the
module -- there's a voltage potential, but no real current there.  If the
voltage stops at a stable value (especially if the value is some multiple of
module open circuit voltage) then you have a ground fault, and the value
indicates how many modules in from the end of the string.

Happy T-day, everyone!

Phil Undercuffler
Conergy



>
>
> ---------- Forwarded message ----------
> From: Nick Soleil <nicksoleilsolar at yahoo.com>
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
> Date: Tue, 24 Nov 2009 20:06:42 -0800 (PST)
> Subject: Re: [RE-wrenches] Megometers
> Hello Wrenches:
>     I have read a few of the archives on this subject, and have a couple
> questions.  I have been testing arrays with an insulation tester, and have
> found that some module types have more leakage than other modules.  Bill
> mentioned Amorphous being really bad.
>     I have found my less expensive tester to work for me, but read in
> another post about the value of a .001 M ohm tester.  Is that level of
> accuracy need?
>     I was testing a Sanyo array today, and was told that ~20M ohms on the
> series string to ground was not a problem.  With the strings isolated, the
> array conductors commonly have voltage readings of 260V+ to ground, but it
> dissipates with the meter connected.  Is this induced voltage caused by the
> leakage current that the manufacturer called 'normal?'
>
> Nick Soleil
> Project Manager
> Advanced Alternative Energy Solutions, LLC
> PO Box 657
> Petaluma, CA 94953
> Cell: 707-321-2937
> Office: 707-789-9537
> Fax: 707-769-9037
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20091125/6b5ef9d3/attachment-0004.html>