Discuss 2391 3 phase rig in the Electrical Forum area at ElectriciansForums.net

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wams

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Sorry Lads and Lasses,
I know this has been discussed many times throughout this forum and other websites but I just can’t get my head round the testing of a 3 phase supply connected to a 3 phase isolator and a DOL starter/motor. There could also be a 3 phase socket.
After finding many solutions I’m finding it difficult to interpret some jargon and some written English literature, apologies to those that I have offended at his stage! It could be just my lack of experience of current electrical jargon and abbreviations.


I know how to measure my R1 + R2 from DB and motor by simply linking between L1 + CPC at DB then measure L1 + CPC at the motor and then repeat the steps with L2 and L3.

I’ve read that I would have to do a separate R1 and R2 from motor to isolator? But I presume you could measure from DB to isolator using the steps outlined above, link L1 – CPC at DB and L1 – CPC at isolator to get R1 + R2 and so on and add the readings of the motors (R1 + R2) and the isolators readings (R1 + R2) together to get the overall (R1 + R2).

If I’m wrong and you have to do a separate R1 and R2 from isolator and motor how would I go about doing this?

My answer I thought would be to link L1 - CPC at the motor and measure L1 – CPC at the isolator and repeat again with L2 and L3 to CPC. (But this is then a R1 + R2 test and not a separate R1 and R2 test)

So if I wanted to measure only R1 would I have to link all phases at motor together using a croc clip and all phases at isolator using the other croc clip?
And for R2 measure CPC from motor to CPC to isolator?

Or am i completly loosing my mind, lol
Thanks
 
God thats confusing. I think the reason they recommend seperate R1+R2 from DB to starter incoming and from starter outgoing to motor is because the DOL starter contacts (L1,L2,L3) will not be engaged during dead testing. If they were (e.g. by manually closing contacts on the DOL stater) you in theory could do 1No. R1+R2 test throughout your entire circuit on each phase. Does that answer your question ?
 
God thats confusing. I think the reason they recommend seperate R1+R2 from DB to starter incoming and from starter outgoing to motor is because the DOL starter contacts (L1,L2,L3) will not be engaged during dead testing. If they were (e.g. by manually closing contacts on the DOL stater) you in theory could do 1No. R1+R2 test throughout your entire circuit on each phase. Does that answer your question ?

Spud1

I dont understand "1No" highlighted in your post? I think it says 1 Number?

What I beleive your saying is that I could measure R1 + R2 from DB to starter incoming, test by linking at the DB and measuring L1 - CPC at incoming starter, L2 - CPC at incoming starter and L3 - CPC at incoming starter.

Then measure L1 - CPC outgoing starter to L1 - CPC at motor and repeat with L2 and L3.

And manually close contact L1, L2, L3 on DOL starter

What ive read is there's no motor connected, but I would have to carry out the test regardless to show competency of electrical testing, I presume anyway?

What about testing the isolator?

Wams
 

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