[RE-wrenches] Finding ground faults

[Dave Click]

Here's the Paul Mync / John Berdner article from SolarPro 2.5:
http://solarprofessional.com/article/?file=SP2_5_pg60_Mync

-David Brearley... er... Click

On 2012/5/22 22:36, Bob Clark wrote:
> Wrenches:
>
> Sorry to bring up this situation again, but I could not find a previous
> discussion thread that talked about step-by-step procedures for tracking
> down ground faults (I believe it was John Berdner who provided the bulk
> of the writing in that regard and it related to high voltage strings—not
> that 75-85 volts per string is all that low).
>
> We have an Outback FLEXpower Two system with 8, 3-module strings
> (Silicon Energy 190W, 25.3Vmp, 7.5 Imp) combined in a Midnite Solar
> MNPV12 combiner with breakers. The cables from the array are routed to
> two different Wiley 4-string pass-through boxes (located under the two
> center strings) and then off of the roof and into the PV combiner.
>
> Up until this week the system has seen several weeks of awesome power
> production. Yesterday, the rains came and the GFDI breaker tripped.
> Every time it rains, the little green breaker on the GFDI trips off.
> That tells me that the ground fault is occurring in a place where at
> least one of the conductors on one of the strings (possibly more) is
> getting wet and conducting current to ground.
>
> It would seem to me that the most likely place for moisture to cause a
> ground fault to occur in this system would be in the pass-through boxes.
> This would mean removing the central modules to access the pass-through
> boxes.
>
> Any of you who have mounted the Silicon Energy modules know that the
> cables are contained in trays along the side of the modules until they
> are routed through conduit to the pass-through boxes. So, if there is
> current going to ground from any of these cables, it could even be
> occurring in any of the 9 trays along side of the modules. I do not like
> the idea of tracking down a ground fault in one of these trays as they
> are all interconnected.
>
> How best (and safely) to track down where the ground fault is occurring?
> Any advice as to the best and safest way to track down the ground
> fault(s) would be greatly appreciated.
>
> *Bob Clark*
>
> */SolarWind Energy Systems, LLC/*
>
>
>
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