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<DIV><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Come on, Bob.<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'>It’s a ground fault in the array. Just one more example why ungrounded arrays are FAR safer.<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><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>See ya!<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Verdana","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Marv<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Director of Technology and Support, North America<o:p></o:p></span></p><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>SolarEdge Technologies, Inc.<o:p></o:p></span></b></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Tech Support Mobile: +530.798.6770<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Mobile: +530.392.0356<o:p></o:p></span></p></div><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";color:windowtext'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext'> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org] <b>On Behalf Of </b>boB Gudgel<br><b>Sent:</b> Thursday, June 30, 2011 10:19 PM<br><b>To:</b> RE-wrenches<br><b>Cc:</b> Nick Vida<br><b>Subject:</b> Re: [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><p class=MsoNormal>On 6/30/2011 8:35 PM, Nick Vida wrote: <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><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'><br>I'd probably use a DC clamp on ammeter. Clamp on and measure the top and bottom current of each string... What comes in ~should~ come out.<br><br>If it's much different on one end vs. the other end of one string, maybe that string is conducting around the path somehow. Remember that<br>sometimes just turning the clamp around and measuring the opposite polarity may measure slightly differently than the opposite polarity and<br>that zero calibration is usually necessary.<br><br>boB<br><span lang=JA>鮑勃</span> <br><br><br><br>************************************************************************************<br>This footnote confirms that this email message has been scanned by<br>PineApp Mail-SeCure for the presence of malicious code, vandals & computer viruses.<br>************************************************************************************<o:p></o:p></p></div></DIV>
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