3 phase quarry pump

[timbobelfast]

I would be checking the windings. Sounds like one set is O/C.
Also check your Isolator does't have a Pole O/C as well!

 

[benji]

Probably got nothing to do with fault but would 10mm be ok with the starting current , if not you could parallel both cables

 

[LankyWill]

Just from a learning perspective, how do you test a motors windings? what results are you looking for?

 

[Marvo]

If you can remove the links you'd test that all three windings are equal resistance and that their resistance is per manufacturer spec if info is available. You'd also megger test between each of the 3 windings to ensure there is no breakdown of the insulation between them.

 

[alanmcm]

Just from a learning perspective, how do you test a motors windings? what results are you looking for?

Test the windings to earth using an insulation resistance tester. Test between each line to earth and expect quite high readings, over 1M ohm is acceptable but I wouldn't like to walk away from a motor knowing the motor is close to that. Then remove links and go between each line and test for resistance and make sure the windings are balanced.

 

[alanmcm]

Probably got nothing to do with fault but would 10mm be ok with the starting current , if not you could parallel both cables

There is 2 10mm cables coming down and are paralleled together.

 

[LankyWill]

cheers mate

 

[alanmcm]

Went in yesterday morning and disconnected the pump from the circuit and tested the cables again for insulation resistance and all OK. Got the quarry operative to start it up, with the pump disconnected, and it didn't trip. Tested voltages and all were fine. So pump at fault. Didn't get a chance to get at the pump as the crane lifted one out and dropped a new one in and the old one was whisked away for repair. When it returns I'll ask what the fault was as I would like to know.

Thanks for all the help and advice.

 

[Darkwood]

It had a winding out, so was 2phasing when when you fired it up from what you put, I think we all picked up on that early on when you explained things, what I don't understand is the 'guy' you said had left this to you because he was elsewhere, (I understand you're on your ladder of learning so aimed at him) this was a basic test procedure and he got it wrong, I think if he cannot nail a basic one like this then he shouldn't be undertaking the work in the first place, It makes me wonder if he's trying to do engineering work off the back of his 17th quals and no formal electrical engineering training or any specific motor diagnostic and repair knowledge at least your training in the correct area for this stuff .... some questions need asking here when you see him next as this has cost the company that runs the site extra down time, it may not be an issue on this site but any other it could be a production hit in the thousands of pounds?
We are always happy to help out but your colleague should have easily diagnosed this one with the correct basic test procedures, have a chat with him next time you see him and please explain to him what was wrong and enjoy taking the credit at his expense .

 

[timbobelfast]

Think I know the quarry site and the electrical contractor. This is basic fault finding for any industrial electrician. The site manager should be calling a meeting!