<html><body><div style="color:#000; background-color:#fff; font-family:arial, helvetica, sans-serif;font-size:12pt"><div id="yiv428819044"><div><div style="color: rgb(0, 0, 0); font-family: arial, helvetica, sans-serif; font-size: 12pt; background-color: rgb(255, 255, 255);"><div id="yiv428819044yui_3_2_0_72_133760583435843"><span id="yiv428819044yui_3_2_0_72_133760583435894"><var id="yiv428819044yui-ie-cursor">Bob I had a tough find one time, when it rained I would have GF when it would dry out no GF </var></span></div><div><span><var>I turned off main DC disconnect, I turned off each circuit breakers for the strings, I opened the grounded conductor of the strings, I connected my Megger at 500 volts I think It might have been maybe 1000 volts, after the fault cleared, the megger found one string that was bad and I located the problem in a J box </var></span></div><div><br id="yiv428819044yui_3_2_0_72_133760583435845"></div> <div
style="font-family: arial, helvetica, sans-serif; font-size: 12pt;" id="yiv428819044yui_3_2_0_72_133760583435849" class="yiv428819044ms__id31217"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;" class="yiv428819044ms__id31235"> <div dir="ltr"> <font size="2" face="Arial"> <div style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); height: 0px; line-height: 0; font-size: 0px;" class="yiv428819044hr yiv428819044yui-non yiv428819044yui-skip"></div> <b><span style="font-weight: bold;">From:</span></b> Steve Higgins <shiggins@outbackpower.com><br> <b><span style="font-weight: bold;">To:</span></b> RE-wrenches
<re-wrenches@lists.re-wrenches.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Wednesday, May 23, 2012 11:27 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [RE-wrenches] Finding ground faults<br> </font> </div> <br>
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<div dir="ltr" align="left"><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial">Bob,
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<div dir="ltr" align="left"><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial">Be careful with that GFDI... It's most likely wired on the output of the controllers, on the battery side. </font></span></div>
<div dir="ltr" align="left"><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial">This can trip if a ground fault is occurring, or if you are exceeding 80 amps of current. With 8, 3 module strings, an edge of cloud event you could have
the 80amp portion of that breaker tripping rather than the GFDI. </font></span></div>
<div dir="ltr" align="left"><span class="yiv428819044-23052012"></span><span class="yiv428819044-23052012"></span><span class="yiv428819044-23052012"><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div align="left"><font size="2" face="Arial">
<div align="left"><font size="2" face="Arial">Steve Higgins</font></div>
<div align="left"><font size="2" face="Arial">Sales Application Engineering Mgr</font></div>
<div align="left"><font size="2" face="Arial">Direct 360-618-4313</font></div>
<div align="left"><font size="2" face="Arial">Outback Power Technologies </font></div>
<div align="left"><font size="2" face="Arial">5917 195th Street N<span class="yiv428819044-11072011">E Arlington, Washington 98223</span></font></div>
<div align="left"><font size="2" face="Arial"></font> </div>
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<font size="2" face="Tahoma"><b>From:</b> re-wrenches-bounces@lists.re-wrenches.org [mailto:re-wrenches-bounces@lists.re-wrenches.org]
<b>On Behalf Of </b>Bob Clark<br>
<b>Sent:</b> Tuesday, May 22, 2012 7:37 PM<br>
<b>To:</b> re-wrenches@lists.re-wrenches.org<br>
<b>Subject:</b> [RE-wrenches] Finding ground faults<br>
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<div class="yiv428819044MsoNormal">Wrenches:</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">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).</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">We have an Outback FLEXpower Two system with 8, 3-module strings (Silicon Energy 190W, 25.3Vmp<span style='font-family: "serif"; font-size: 9pt;' class="yiv428819044ms__id31255">,
</span>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.</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">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.</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">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.</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">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.</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal">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.</div>
<div class="yiv428819044MsoNormal"> </div>
<div class="yiv428819044MsoNormal"><b><span style="color: rgb(227, 108, 10); font-family: Papyrus;" class="yiv428819044ms__id31256">Bob Clark</span></b></div>
<div class="yiv428819044MsoNormal"><b><i><span style="color: rgb(227, 108, 10); font-family: Papyrus;" class="yiv428819044ms__id31257">SolarWind Energy Systems, LLC</span></i></b></div>
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