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Induction Motor


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I have got a imported machine which is running on 480V AC with 60HZ Frequency. In INDIA supply voltage is 440V AC with 50 HZ Frequency.

1)What changes required to do for running the Induction motor satisfactory ??

2) Increasing voltage to 480 V using Stepup Transformer & keeping the Frequency 50 HZ. What will happen to Motor performance ie Torque/Speed/Current.


Pl suggest me a solution to run the machine.



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Hello Abhi


Welcome to the forum


If you run the 60 Hz motor on 50Hz there are several things to consider:

1) the motor will run slower. i.e. a 60Hz 2 pole motor would run at just under 3600 rpm and a 50Hz 2 pole motor would run at just under 3000 rpm.

2) To run the motor on 50Hz, you must keep the V/Hz ratio the same. i.e. 480/60 = 400/50 so the maximum voltage at 50Hz should be 400 Volts. If you operate at a higher V/Hz on this motor, you will over flux the motor and cause overheating.

3) The maximum power rating rating of the motor reduces by the frequency reduction. i.e. the power reduces to 5/6 of the 60Hz rating.



1) reduce the voltage to 400 Volts and reduce the motor loading.

2) Apply a Variable speed controller to increase the frequency.


Best regards,

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Thank u very much marke for the quick reply..

Will u clarify some more points.

1) What will be the effect on other instruments like Temp. Controller/Timer/Contactors/Relays etc. which are originally running on 60 Hz. & now i want to run on 50 HZ.

PL explain.

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It realy depends on the equipment.

Purely inductive components like traditional contactor coils and relay coils are usually affected by the frequency in the same way that the motors are. i.e. you need to reduce the terminal voltage to 5/6 of the 60Hz rating. Some newer coils are electronic and are the same voltage for 50 Hz and 60Hz.


Temperature controllers and similar are usuallydesigned to operate on 50 Hz or 60Hz with the same terminal voltage, however there are some that are 60Hz only. If you apply 50 Hz, at the same terminal voltage, you could burn out the internal transformer. If you reduce the voltage to suit the frequency, you will possibly have insufficient output voltage to run the internal electronics correctly.


Essentially, you need to verify for each piece of equipment.


Best regards,

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