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Asynchronous Induction Motor


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Application is a rotary breaker employing a 110kw 1485 rpm 180 amp motor which was a pope motor which is no longer made in Australia.

We need a replacement motor with a no load current of 28.6 amps, as the rotary breakers employs a control loop using the motor current to control the feed rate. The lower the NLA the better, as at present the motor is running at 70 amps with the breaker empty and the setpoint is 130 amps which slows the feeder down if the current exceeds the setpoint and at 170 amps stops the feeder.

The feed is been restricted to 800 TPH instead of 1500 TPH

They replaced the motor with another brand and what I have discovered is nearly all the current motor manufactures have a no load current in the 50 to 60 amp range for a 110kw motor.

For the time being we have doctored the current readings from the motor into the plc to allow higher feed rates into the breaker. Running the risk of bogging the breaker.

So if anyone can tell me of a motor that fits the bill.



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Hello phild


The no load current of an induction motor generally falls between 20% and 60% of the rated current of the motor. Magnetising currents of less than 20% are not normal and will result in very poor torque available from the motor. You are looking for a motor with a magnetising current in the order of 10 - 15% of the rated current of the motor.

I think that you will be looking for a very very long time!!


I would recomend that you use a shaft torque monitor like the Emotron M20 to give you an output proportional to the shaft torque of the motor an this will gie you a much better result than you had before.


Best regards,

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