motor's current load monitoring

[Yahoo1]

I am using a AC brushless servo motor (3 phase 220VAC) and want to monitor the current load using a current sensor.
My question is: Do I have to use a 3 phase current sensor or a single phase one is ok?

Thanks.

 

[aolalde]

If the motor windings are in good condition the currents are balanced with 120 Deg spacing, then a single phase line current will give you information of the motor current.
If detail analysis including phase angle are required you should monitor each phase.

 

[Yahoo1]

Hi alalde,

Thank you very much for your reply.

I think a single phase sensor is ok for me because I don't require phase angle and high accurat measurement.

Thanks.

 

[buzzp]

Is this just for information only or is it to activate some type of motor protection? If it is for information only, then it would be okay. However, if it is for some type of motor protection circuit then use all three.