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fawaazrulz
Member

Join Date: Oct 2010
Posts: 5

Calculation of Motor Torque

10/08/2010 2:14 PM

hello guys, I have to calculate the torque of an existing motor so that I can replace it by another one based on the torque obtained for the actual one. here are the values i have for the existing one: Output - 200KW; Volts - 400V; Frequency - 50Hz; Number of Poles - 6; Speed - 1400rpm; Motor Weight - 1900kg; Can anyone help me in finding the required torque based on the above values please!! Regards, Fawaaz
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mountk2
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Join Date: Jun 2010
Posts: 348
Good Answers: 10
#1

Re: calculation of motor torque

10/08/2010 2:50 PM

Shaft torque = (9.55 x Power Output) / Speed

Please note that you do not need to calculate shaft torque for motor replacement, closely match the speed-torque characterstic curves of new motor with the existing one.

The characterstic curves are provided by the manufacturer of the motor.

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fawaazrulz
Member

Join Date: Oct 2010
Posts: 5
#2
In reply to #1

Re: calculation of motor torque

10/09/2010 12:43 PM

Fanx 4 your reply mountk2, Actually I do not have the speed-torque characteristic curves of the existing one. That's the problem. What should I do in that case?? By using the formula you gave me above I have got the torque, which is equal to 1364.2Nm in that case, what's the proceeding now? In fact I suppose for the replacement of the existing one, which is 200KW, a motor of in the range 200KW, 220KW or 250KW would do the job. But how do I get the calculation to choose the best one??
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mountk2
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Posts: 348
Good Answers: 10
#3
In reply to #2

Re: calculation of motor torque

10/09/2010 4:27 PM

Get the characterstic curves for the load (pump etc.) and closely match the new motor to suit the curves of load.

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fawaazrulz
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Join Date: Oct 2010
Posts: 5
#4
In reply to #3

Re: calculation of motor torque

10/10/2010 3:07 AM

One thing I would like to ask ya mount... the formula u gave me at first, does it apply to synchronous motors?? because I forgot to specify that it was a synchronous motor. :S
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