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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Nick,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>How can you conclude that there was nothing wrong in regard to ground faults. What was your reasoning that lead you to that conclusion. I think there is doubt on your conclusion unless half the wiring in the second string is backwards.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Bill.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>Nick Vida<br><b>Sent:</b> Thursday, June 30, 2011 8:36 PM<br><b>To:</b> wrenches<br><b>Subject:</b> [RE-wrenches] how would you measure a partial short circuit<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><div><p class=MsoNormal style='margin-bottom:12.0pt'><span style='font-family:"Courier New"'>Hi wrenches.<br><br>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. <br>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.<br>Do any of you have any thoughts on how one would measure for such a thing?<br><br>nick vida<o:p></o:p></span></p></div></div></div></body></html>