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Running Of A 500V Compressor Motor On 400V


AB2005

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Dear Friends;

 

We have a screw air compressor Atlas Copco GA808 which has a 75KW 500V motor runs on star delta. As we have 400V power supply system, so initially we want to run this compressor on 400V to test it with load. So what will happen with its motor when we run it on 400V? Obliviously its torque will be reduced but for how much percentage?

"Don't assume any thing, always check/ask and clear yourself".

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Hello AB2005

 

The high slip conditions will result in a torque reduction proportional to the voltage reduction squared.

 

In the Run condition (low slip) the current will increase with the voltage reduction. This will increase the I2R losses, so I would reduce the shaft load such that the maximum current is equal to the rated current of the motor. This will reduce the KW load by the voltage reduction.The full load slip will be increased due to the reduced flux in the iron.

 

Best regards,

Mark.

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  • 1 month later...

Gidday AB2005

 

I would be careful here. A Lot of these atlas copco three phase compressor motors are two part start windings. NOT to be confused with star/delta ..even though they appear to start on the ones and then the twos of the UVW's. They are actually center tapped series/parallel windings. I have detailed many and they are always bloody complicated. The 500V vs 400V should be negligible. It should still start, only the current will be lower or higher proportionally.

 

 

 

Hello AB2005

 

The high slip conditions will result in a torque reduction proportional to the voltage reduction squared.

 

In the Run condition (low slip) the current will increase with the voltage reduction. This will increase the I2R losses, so I would reduce the shaft load such that the maximum current is equal to the rated current of the motor. This will reduce the KW load by the voltage reduction.The full load slip will be increased due to the reduced flux in the iron.

 

Best regards,

Mark.

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