Greetings Every one.

I actually have two questions about IM during solo run, Does the rotor have current while there is no load, I already know that the rotor is just a group of closed conductors, which by Faraday's law that will have an induced current if they were placed in a changing magnetic field( stator is fed by AC power), so I assume that there should be current in the rotor but I'm still in doubt.
Second Q, if the air gap is not uniform in the rotor, how would it affect the stator and rotor() currents.


Thank you in advance.

 

An AC induction motor with zero load will never come up to synchronism, otherwise there would be zero current in the rotor.
Therefore a few cycles of 'slip' frequency is present, just enough to overcome any windage and friction to produce sufficient current keep the rotor in motion.
Max.

 

if the air gap is not uniform in the rotor, how would it affect the stator and rotor() currents.

I think it would tend to add distortion to the currents, making them non-sinusoidal.

 

Second Q, if the air gap is not uniform in the rotor, how would it affect the stator and rotor() currents.

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In the rotor? That would make for a very unbalanced rotor, which could be disastrous!
What is the reason for the questions?
Max.

 

In the rotor? That would make for a very unbalanced rotor, which could be disastrous!
What is the reason for the questions?
Max.

Cuz I'm facing a situation with unbalanced rotor of a compressor and there is 10 A difference between Ia and Ic

 

Is this a 1ph or 3ph?
For 1ph there will be significant difference between the main winding and the split phase winding.
If 3ph have you ran it off load, no shaft connection?
It could be a partial winding short.
Max.

 

Is this a 1ph or 3ph?
For 1ph there will be significant difference between the main winding and the split phase winding.
If 3ph have you ran it off load, no shaft connection?
It could be a partial winding short.
Max.

It's a 3ph and the shaft is uncoupled with the compressor (solo run)

 

Sure its not bearings?
What are the actual symptoms, apart from current imbalance?
Max.

 

there

Sure its not bearings?
What are the actual symptoms, apart from current imbalance?
Max.

is a high horizontal vibration at the NDE of the motor!!

 

If the stator has no defect then I would suspect bearings and/or thrust washers for keeping the rotor centred, either way it might pay to dismantle and inspect.
Max.