KC-120 Output ?s [RE-wrenches]

[William Miller]

Wally:

Were the voltage tests made while the system was connected to the charge
controller?  Could the charge controller be loading the panels with an
inconsistent load?  The load could change from the moment you are checking
one module to the moment you are checking another.  Watch the overall
charging current for a while to see if it varies.  If it does, maybe you
should bypass the charge controller temporarily with a direct connection to
the batteries while you check loaded current and voltage.

Good luck.

William


At 02:23 PM 10/11/01 -0700, you wrote:
>Greetings Wrenches and interested others,
>
>I have a bit of a mystery unfolding on a two Zome tracker installation with
>twelve
>KC-120 modules on each tracker. Each tracker has three strings of four
>modules wired in series for the 48 volt nominal system. The system became
>operational in
>March, 2001 and performed as expected then.
>
>A quick check of the system two weeks ago showed that there was no output on
>one of three strings on each tracker. Reduced output on the other strings
>was apparent also.  A quick check of the suspect string showed no output on
>one of the modules. Due to travel and work schedule, yesterday was my first
>chance to investigate since then.
>
>The previously nonworking module was now working, which means either an
>intermittent failure or a misapplied test procedure.
>I discovered short circut current flows for all modules in the 6.22 - 6.50
>range with 7.45 being rated peak Isc.
>The voltage under load however ranged from a low of 10.9 -16.4 volts.
>The rated peak voltage is 16.9.  Twelve of the modules are less than 14
>volts,
>five are14 - 15.0 volts, and seven are above 16 volts.
>
>These were tested with a Fluke 36 and at the +/- terminals of each module
>while connected to the Pulse 60 amp charge controller. Isc was tested with a
>DMM. Series wiring is #12 THHN in FNMT pvc conduit to a fused combiner box
>on the tracker post.
>Wide voltage variation from module to module is seen on five of the strings.
>
>What  factors other than internal failures would give this result, and how
>so?
>
>Thanks for your shared knoweledge in advance.
>Wally Stahle


__________________________________________________________________
William Miller
SLO Communications: Communications and Power Systems Consulting
PO Box 50, Santa Margarita, CA 93453
Voice :805-438-5600		Fax: 805-438-4607	VMail: 805-546-4875
email: wrmiller at slonet.org
License No. C-10-773985
_____________________________________________________________
Compatibility:
Word processor: WP7
Spreadsheet: Quatro Pro 7
CAD: Microstation 95, DXF, Visio 4.1T
_____________________________________________________________
"I stand by all the misstatements that I've made." Dan Quayle
__________________________________________________________________

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com

==^================================================================
EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9
Or send an email To: RE-wrenches-unsubscribe at topica.com
This email was sent to: michael.welch at homepower.com

T O P I C A -- Register now to manage your mail!
http://www.topica.com/partner/tag02/register
==^================================================================