250 kW Motor Problem

We have a 250 kW 440 V motor in our factory. the motor is taking about 100 A current in all 3 phages when there is no load. but when small load applied one phage voltage is dropped to 75 A and other two are taking about 135 A. I have checked all connectors are ok. Motor coil resistance are all equal to each other. Cable insulation is also ok. supply voltages are ok.

Can anyone tell me where is problem? Is it motor internal coil problem or anything else.please help.

We have a 110kW (400V / ~2800U/min / ABB / IE2) motor for a saw. He takes between 62 to 65 Amps when the saw is running but not cutting. So I guess 250kW / 100A is ok. @collin: Amps without PF has nothing to do with real power ...

I never heard of a problem like you have now. But my guess would go to a problem in a coil. If the problem would be in the rotor, it would happen to all phases. Maybe you can see something with an IR camera or later smoke will tell you ;-)

We had once a problem with the saw motor I talked before. He was "powerless". Without load was also everything normal, with load he took max. about 80 Amps even he was blocked to zero speed. But it happened to all phases an was an rotor problem.

is it safe to run the motor with the present condition?

My guess would be better not. If it is a problem in a coil, maybe in a motor revision they can fix it. If run the motor you can have a short in the coil and then you loose probably the whole motor ...

Difficult to say from here what to do ... I don't know the application and so ..

think about ... what happen the motor goes broken when in full production

you said under low load ...what does happen with more load? Does he have "power"?

I would change the motor now ... or at least order a spare one right now if you don't have one.

So back to beginning. The worst thing is you loose the whole motor by a short in the coil ... but what is with the production line?

How did you realize anyway something is wrong with the motor? Or is it a new plant and you just saw it when you started the motor the very first time?

age of the motor is 3 years. we check phase current every week. this is first time we saw the problem.