<html><body><span style="font-family:Verdana; color:#000000; font-size:10pt;"><div>Carl- These ungrounded inverters are not designed to tolerate ground faults. That's why they test RISO-- resistance to ground-- before turning on. There is no ground fault fuse to blow so if you induce a ground fault while it is already live you risk unlimited ground current from the AC neutral to DC input, killing the inverter. </div><div>Look for Engineering Bulletin 1002-2010 from SolarWorld for a good explanation. I have attached it here.<br></div><div>Larry Crutcher's suggestion of using a 40k ohm resistor makes good sense.</div><div><br></div><div>Don Barch</div><div>Energy Solar<br></div>
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<br>
Message: 1<br>
Date: Mon, 25 Nov 2013 16:04:05 -0500<br>
From: Carl Adams <<a href="mailto:swingjunkie@gmail.com">swingjunkie@gmail.com</a>><br>
To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
Subject: [RE-wrenches] Safely inducing arc fault and ground fault in a<br>
completed array<br>
<br>
Wrenches,<br>
<br>
We just completed an install with the SMA STP12000TL-US. I would like to<br>
induce two fault conditions into the system 1) ground fault, and 2) arc<br>
fault, in a manner that is both safe to equipment and personnel, in order<br>
to see how these units respond to those conditions, and in particular how<br>
the arc fault is cleared, after detection. (assuming it is detected)<br>
<br>
Any suggestions appreciated.<br>
<br>
With Regards<br>
Carl Adams NABCEP 031508-1<br>
SunRock Solar<br>
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Message: 4<br>
Date: Mon, 25 Nov 2013 14:55:38 -0700<br>
From: "Larry Crutcher, Starlight Solar Power Systems"<br>
<<a href="mailto:larry@starlightsolar.com">larry@starlightsolar.com</a>><br>
To: RE-wrenches <<a href="mailto:re-wrenches@lists.re-wrenches.org">re-wrenches@lists.re-wrenches.org</a>><br>
Subject: Re: [RE-wrenches] Safely inducing arc fault and ground fault<br>
in a completed array<br>
Message-ID: <<a href="mailto:65D3D886-837D-4D53-81A7-F4973A1F0792@starlightsolar.com">65D3D886-837D-4D53-81A7-F4973A1F0792@starlightsolar.com</a>><br>
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<br>
Carl,<br>
<br>
Assuming about 400 volts, a 40k ohm resistor from PV negative to ground should trip the ground fault. Solder up to some test leads, insulate the resistor and make the short. You'll only be conducting about 2 Watts through the resistor.<br>
<br>
Arc fault, on the other hand, can be very complex. Series, parallel, inter string and more, pulsed, constant, varying intensity?..it get's beyond my understanding quickly. I'll bow out here and defer to others that are far more educated.<br>
<br>
Larry<br>
<br>
On Nov 25, 2013, at 2:04 PM, Carl Adams <<a href="mailto:swingjunkie@gmail.com">swingjunkie@gmail.com</a>> wrote:<br>
<br>
Wrenches,<br>
<br>
We just completed an install with the SMA STP12000TL-US. I would like to induce two fault conditions into the system 1) ground fault, and 2) arc fault, in a manner that is both safe to equipment and personnel, in order to see how these units respond to those conditions, and in particular how the arc fault is cleared, after detection. (assuming it is detected)<br>
<br>
Any suggestions appreciated.<br>
<br>
With Regards<br>
Carl Adams NABCEP 031508-1<br>
SunRock Solar<br>
_______________________________________________<br>
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