How to select a suitable 3 phase induction motor for a compressor

[menaka100]

I need to calculate the capacity 0f a 3 phase induction motor that suitable for the compressor which gives maximum efficiency. The load of the compressor is 150kW. Now I want to know how we calculate the capacity of the motor that gives maximum efficiency

 

[burnt2x]

"Do not guess, when you can calculate. Do not calculate, when you can measure." Archimedes

Compressor manufacturers publish equipment efficiencies at rated load. Since you already have the compressor, look for your compressors efficiency, divide your compressor load by the compressor efficiency to get the required motor output power. This calculated motor output should be divided by your motor efficiency to get the correct motor size for the compressor duty.
BTW, if you don't have data on your compressor and you have motors larger than the compressor, might as well couple your compressor with the motor and do a "measurement" of power input(1.732 x V x I x PF) for your compressor; as Archimedes suggests.

 

[itsmoked]

Don't forget any grearing needed and it's impact on the system.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LionelHutz]

You work with the motor suppliers to find a motor that is the most efficient at the load you are applying to the shaft. In this case, a 150kW motor that is the most efficient. Am I missing something?

Burnt2x - I'm not sure I understand why you'd divide the required motor output power by the motor efficiency. The motor rating is the output power on the shaft. The input power to the motor includes the motor efficiency.

 

[burnt2x]

You're right Mr. Hutz. I missed and was thinking about source power requirement.