[RE-wrenches] how would you measure a partial short circuit

[boB Gudgel]

On 6/30/2011 8:35 PM, Nick Vida wrote:
> Hi wrenches.
>
> I had an interesting case today that I have been thinking about since 
> it happened. I dont have all the details because the homeownter had to 
> leave before I was done with the service call, but here is what I do 
> know. SB5000 with 2 strings of 15 modules. String one was 437 vdc, and 
> string 2 was 247vdc. I decided to look for a ground fault, and I 
> turned off the inverter. I measured for ground faults and found no 
> evidence of anything wrong in that regard. As the homeowner was out of 
> time and wanted me to go, I re-landed the wires in the dc disco, and 
> when I replaced the fuses, I noticed a minor arc when one of the fuses 
> was going it. Although I had no time to measure it, I think that there 
> might be a partial short circuit, possibly with one complete string 
> and some panels of the other string, and the remaining panels on the 
> second string. My mind was racing with how I could have measured for a 
> partial short circuit without seeing it as an arch. I can imagine such 
> a thing on a bigger system being a dramatic electrical event.
> needless to say, I cant wait to get back there and go through the 
> signal path properly and find out what the electrician did. And of 
> course i realized that replacing the fuses in such a questionable 
> situation was probably not the best idea.
> Do any of you have any thoughts on how one would measure for such a thing?
>
> nick vida


What does this part of your question mean ??

"I noticed a minor arc when one of the fuses was going it."

boB



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