Just out of interest.....?

[Prince1983]

Hi all,

just wondering if anyone ever uses their insulation resistance tester for a dielectric absorption ratio test if they find their test readings around 100Mohms?

 

[Guest55]

youre new around here arent ya fella ?

;-)

 

[spark 68]

Never really been asked to do a DAR test, more to the point most sparks work to BS7671 which does not allude to that type of test.

Most witness testing on LV switchgear I have done just ask for IR test @ 1000V then pressure test (Hi-Pot) @ 2.5kV for 25 secs then IR @ 1000V again.

 

[Guest111]

never needed too,i take it you mean IR at 30 seconds and again at 60 seconds and DAR = 60 seconds measurement divided by 30 seconds measurement?

 

[Guest55]

not all test equipment has such a function
my does though
fluke for the win !
;-)

 

[Prince1983]

I know. Just wondering about it after reading about it and thought it could be a useful unofficial test to carry out when getting low IR readings.

@biff sort of. I once posted and got vilified! A basic mistake.

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And the megger!

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Yes that's the one

 

[Guest111]

I know. Just wondering about it after reading about it and thought it could be a useful unofficial test to carry out when getting low IR readings.

@biff sort of. I once posted and got vilified! A basic mistake.

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And the megger!

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Yes that's the one

just test as normal and get on with it,if an IR is low it's best investigating and carrying out whatever is needed.

 

[Guest55]

100 meg isnt low though.
in fact at 100 meg i'd stop even thinking about additional testing , youre good to go.

have we been kinder on your 2nd thread ?

 

[spark 68]

100 meg isnt low though.
in fact at 100 meg i'd stop even thinking about additional testing , youre good to go.

have we been kinder on your 2nd thread ?

It is if you are measuring Gig ohms though, lol

 

[Prince1983]

Yes, thank you

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Why don't my smileys come up?

 

[GLENNSPARK]

ill

Yes, thank you

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Why don't my smileys come up?

better ask these lot:

http://www.youtube.com/watch?v=TgsoPbS19-Y

 

[MDJ]

Hi all,

just wondering if anyone ever uses their insulation resistance tester for a dielectric absorption ratio test if they find their test readings around 100Mohms?

I use mine for meggaring the nipples of apprentices, nothing like it tbh, I actually enjoy it :grinningelf:

 

[Prince1983]

I use mine for meggaring the nipples of apprentices, nothing like it tbh, I actually enjoy it :grinningelf:

evil man! Lol I hope you're kind enough to use the 60 second test and not the 10 minute one! Lol

 

[Knobhead]

In response to the OP yes, every week. The test gear cost £10K+ so not for home use. Plus you have to be authorised to use it.

I would be looking for 1TΏ @5KV within 30 seconds, you have to allow for capacitance charging. If it didn’t reach that then the print out would have the testers weather observations added. Below 500MΏ and not rising after one minute, a steady rise could get good results but liable to cause damage by stress or flashover. Total strip down of the circuit would be the result of a bad test.

Why do you want to know about this sort of gear? It isn’t run of the mill stuff.

I’ll go in to it more via PM if needed, but if it’s just for interest forget it. Read your books.

 

[Engineer54]

LV DAR testing, normally conducted on manufactured plant etc. Some industries may make regular or periodic tests, but generally it'll not be a required test for most installations post initial commissioning and testing. Regular IR spot testing for 1 minute is more than adequate in the vast majority of cases. Only when you see good IR levels decreasing is a DAR test useful to confirm or otherwise that the insulations dielectric is breaking down...