OCPD for VFD

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philly

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I have recieved an VFD in an enclosure that was ordered. The 480V VFD enclosure was supplied with a 100A breaker on the line side of the drive connected to the disconnect handle.

I am feeding power to this drive from a remote MCC. Before I had the drive here I sized the cables to the drive based on the fact that the cables need to be sized for at least 125% of the drives input rating which is 48.3A. After derating cable and selecting breaker I purchased a #4 feeder cable with a 70A feeder breaker?

Is it o.k. to have this 70A feeder breaker be less than the 100A breaker in the drive? Is this a poor design or will it present any problems?
 
philly said:
I have recieved an VFD in an enclosure that was ordered. The 480V VFD enclosure was supplied with a 100A breaker on the line side of the drive connected to the disconnect handle.

I am feeding power to this drive from a remote MCC. Before I had the drive here I sized the cables to the drive based on the fact that the cables need to be sized for at least 125% of the drives input rating which is 48.3A. After derating cable and selecting breaker I purchased a #4 feeder cable with a 70A feeder breaker?

Is it o.k. to have this 70A feeder breaker be less than the 100A breaker in the drive? Is this a poor design or will it present any problems?
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IMO, I see nothing wrong with your setup.
 
I agree with mcclary's electrical and will add that may not really be a 100 amp breaker it may just be a 100 amp molded case switch.
 
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