The IEC 62446 standard for IRT on PV is: Voc@STC x 1.25 = 120 V to ≤ 500 V, test to 500 V Voc@STC x 1.25 = > 500 V, test to 1,000 V
They specify using one of two methods: 1. With the array short circuited (a la the Seaward test meter style) 2. Testing both positive and negative to ground - both the negative and positive leads need to be isolated (fuse open/breaker off, and disconnected from parallel busbar connections). In my experience, putting the meter in series (meter positive to PV negative, meter negative to ground) is usually sufficient for finding ground-faults. Make sure the meter-to-ground connection is low resistance, and that the connection point is something that is actually bonded to the equipment grounding system. Temperature, humidity, and the amount of "glass" being tested will have significant impacts on measured results, but you're really looking for an outlier, assuming it isn't a hard fault that could've been found with a DMM or a visual inspection. Always a good idea to check with the module manufacturer to see if they have documentation on their recommended procedure. Cheers, Brian Mehalic NABCEP Certified Solar PV Installation Professional™ R031508-59 National Electrical Code® CMP-4 Member (520) 204-6639 Solar Energy International http://www.solarenergy.org SEI Professional Services http://www.seisolarpros.com On Wed, Apr 10, 2019 at 3:07 PM <drake.chamber...@redwoodalliance.org> wrote: > That is very helpful. If I do the high voltage test, can I test from both > positive to the frame and negative to the frame? > > Thanks, > > Drake > > > > ----- Original Message ----- > From: > "RE-wrenches" <re-wrenches@lists.re-wrenches.org> > > To: > "RE-wrenches" <re-wrenches@lists.re-wrenches.org> > Cc: > > Sent: > Wed, 10 Apr 2019 10:35:50 -0700 > Subject: > Re: [RE-wrenches] HV Module Testing > > > Drake > I have performed test for manufactures and you must keep the test voltage > under the max rated voltage of the module, we have a bunch of tests we do > but in short, you need to see the modules up close, look at the edges and > back sheets look for green, brown or black spots, you need to do testing > both dry first then wet if it is a ground fault concern. Most of the time > the visual will find the issues but you still want to verify what you think > you see. Make sure you look at the wiring to and from, the combiner box(s) > or even the inverter(s). > > On Wed, Apr 10, 2019 at 8:31 AM Drake < > drake.chamber...@redwoodalliance.org> wrote: > >> Hello Wrenches, >> >> We are troubleshooting an array of Orion modules, either 230s or 250s. >> The array is showing a ground fault. >> >> We would like to test these modules with an insulation tester? >> >> We would like to apply 500 V or 1000 V to each the + and – and test >> resistance to ground. >> >> Is this practice safe for individual PV modules? Is there anything I >> should be aware of before attempting this? >> >> Thanks, >> >> Drake >> >> Drake Chamberlin >> >> >> >> >> >> *Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified >> Solar PV 740-448-7328*http://athens-electric.com/ >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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