Help with 3 phase star delta motor

[marconi]

Can you not disconnect feed to motor at the s/d contactor? Yes, 500V only to begin with and perhaps let us have a look at the readings. The continuity should all be about the same. IR depends on the state of the windings.

 

[Bobster]

The size of that motor unless something about it's frame size, shaft size etc is really uncommon. If it has been a winding failure, it'll be more cost effective to buy new rather than re wind.

I've always found the break even point to be around 30kw and bigger is worth rewinding.

 

[marconi]

How to test a three phase induction motor:

How To Test Three - Phase AC Motors ~ Learning Electrical Engineering - http://www.electricalengineeringtoolbox.com/2015/12/how-to-test-three-phase-ac-motors.html

 

[marconi]

This is the firm that manufactured the motor:

http://browneuropeltd.com/catalogues/Euromotor AC Electric Motor 2007.pdf

 

[Lucien Nunes]

Don't substitute... diagnose! Changing the contactor might fix it, but only in the same way that fitting a new engine might fix a car that won't start.

You should be able to verify the motor condition with 90% certainty using about ten 5-second tests, done from the control cubicle if it's more convenient than at the motor. Test the windings from the motor side of M and D; obviously you wouldn't be able to distinguish between a winding fault and a damaged cable - but at least you will be able to identify a disconnect, an interwinding short, a single winding short etc. IR from each winding to each other and to earth at 500V, and resistance of the three windings each of which will have one end on M and one on D (&S).

If something is amiss - insulation down, one winding O/C, or more than say 10% difference in winding resistance - then you will have to repeat the tests at the motor terminal box. The operation of the contactors can be proven likewise at either end, provided you can keep the control supply on with the 3-phase off. Or if live testing is permissible then you can probably find the fault with just the three line current clamp tests in a matter of seconds.

 

[Pastyspark]

Been reading this thread and making me even more twitchy than when I started.
Got a star delta starter sat in my van for over 2 months now. Been putting job off as it's for a 40 year old compressor or may be older with the old style starters where you flip a lever down to start it then quickly up to run but it won't stay up any more. ( waiting for the puns )
Plus the building is a old aircraft hanger that was removed from local raf base some time after the war and rebuilt on site and I don't think the electrics have been touched since. Need to discuss with customer all the work on mains that need doing first.