Voltage

[bob14]

Hi,

 

I am wondering on the effect of running LV motors designed for 380 V operation on 415 V supply. I presume the voltqge rise 9 % should be insignificant. The motor would be slightly overfluxed but should run with less losses.

Any comment.

 

Bob

[marke]

Hello Bob

 

If the motor has been wound for 380 volts, there will be some margin to alow the motor to operate at 380 + 10% as a minimum.

 

As you increase the voltage with a constant load, the iron loss will increase and the copper loss will reduce. At a point in the voltage, the iron will begin to saturate and the magnetizing current will rapidly rise for small increase in voltage and the associated iron loss will also rise dramatically.

Provided that you operate below saturation voltage, there will be no issue.

I would expect that the saturation voltage would be above 415 volts for 380 volt motor.

 

Most 380 volt motors are wound for operation on supplies between 380 and 415 volts so will actually operate at 415V plus 10 - 15%

I see no problems. If you are concerned, connect the motor under open shaft conditions and ensure that the magnetizing current is not excessive and that the motor does not heat significantly operaing under open shaft conditions.

 

Best regards,

Mark.