Megging PV Arrays [RE-wrenches]

[Graham Owen]

Hi John,

You wrote: Anyone know why the GFDI value is set at 1 Amp when it takes
about 0.050 Amps to stop your heart ?  

I thought it was high voltage that defibrillates and refibrillates
hearts?

Graham



-----Original Message-----
From: jberdner at sma-america.com [mailto:jberdner at sma-america.com] 
Sent: Thursday, February 06, 2003 4:36 PM
To: RE-wrenches at topica.com
Subject: RE: Megging PV Arrays [RE-wrenches]


Joel:

The Sunny Boy automatically meggers the array as part of the initial
start up sequence.  The inverter will not clear the yellow GFDI LED
unless it passes the megger test.  

In Europe, where they do not kneel before the temple of the false god of
array conductor grounding, the Sunny Boys continuously megger the array
and store values of leakage from either the positive and negative array
conductors. You can even record this data and check it from time to time
to see if you have an insulation system breakdown.  That way you can see
that the array leakage current is getting to high and take corrective
action before it becomes hazardous.   

Here is the USofA we don't believe in any of them new fangled ideas and
stick with our 150 year old traditions to ground everything even if it
don't need no ground. Higher costs, reduced reliability, and less safety
that's the way we like it.

Question: Anyone know why the GFDI value is set at 1 Amp when it takes
about 0.050 Amps to stop your heart ?  
Answer: Because John Wiles had a 1 Amp Heinemann breaker in his garage
at it worked pretty well.

Question: Anyone know why the 690 requires us to ground the PV negative
?
Answer: The guy who wrote that into 690 told me he didn't remember but
"It seemed like a good idea at the time"

If you have any questions, or if I can be of any further assistance,
please do not hesitate to contact me.

Best Regards,

John Berdner

SMA America, Inc.
12438 Loma Rica Drive, Unit C
Grass Valley, CA  95945
530.273.4595 (voice)
530.274.7271 (fax) 


-----Original Message-----
From: Joel Davidson [mailto:joeldavidson at earthlink.net] 
Sent: Thursday, February 06, 2003 2:21 PM
To: RE-wrenches at topica.com
Subject: Megging PV Arrays [RE-wrenches]

Wrenches:
Quick survey.
Do your megger test the PV array string circuits that you install? Yes
or No. If yes, Dry or Wet? Do you megger test as a Standard Practice or
as a Customer Requirement? Thanks for your feedback. Best regards, Joel
Davidson

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