A couple of IR testing questions

[sambotc]

Do you carry out AC IR tests with generation meter (elster) connected ie from inverter to disconnected conductors at the board, or will this damage the meter? I've been linking it out but apart from the test not being true to the installation it can be a pig if the meter is in an awkward spot!

Also IR testing on the DC side, what test voltage do you use? 1000v is the max rating on the DC cable, but 500v is sometimes less than the string voltage? Do you carry this test out with the inverter connected but off?

Sorry, being fairly new to the electrical side, IR testing always gets me worried i'm going to damage something!

Thanks in advance

Sam

 

[JulianC]

Either link out the meter or test L-E and N-E - you shouldn't damage the meter testing L-N with it in the circuit but it will give you a dodgy reading.

I IR test the DC side with the inverter disconnected. If my string voltage is over 500v then I test at 1000v, as long as the cables/panels are rated to handle it (as far as I am aware, they all are). For string voltages under 500v, I test at 500v but for no other reason than I am a big girls blouse and don't want to damage those lovely expensive panels. Yeah, I know, they can take 1000v.....

 

[mydigitalhome]

I thought you only had to test at 500v and jobs done why test at 1000v?

 

[JulianC]

If your string voltage is over 600v for example, what good is a 500v test?

 

[sambotc]

Thanks JulianC

Is there a published minimum permisable reading for the DC side IR test?

 

[IronLiver]

It's in the back of the DTI guide Appendix C table 1 if testing + and - shorted together to E then 0.5MOhms at 500V and 1MOhm at 1000V. Test voltage varies if testing + to E and - to E separately but you're governed by your tester.

 

[sambotc]

Found it thanks Ironliver

 

[yellowvanman]

It's in the back of the DTI guide Appendix C table 1 if testing + and - shorted together to E then 0.5MOhms at 500V and 1MOhm at 1000V. Test voltage varies if testing + to E and - to E separately but you're governed by your tester.

Those minimum values are from the old 16th Edition regs - so you may want to cosnider the 17th edition values which are double!

 

[IronLiver]

Thanks yellow will check my versions