line reactor protection?

[dougjl]

I have a question concerning code. I have a 40 HP motor being run by an allen-bradley VFD that will be set to protect the motor. I have the incoming line going through an 80A trip circuit breaker (which is the size A-B recommneds for the drive) and then to a line reactor. The line reactor is rated for 55A continuous and 200% for 3 minutes. My question is: Is the reactor sufficiently protected by the drive? I belive a 70A (125% of 55A)breaker would be called for by code, unless somehow the drive can be considered the protection device.

Any thoughts?

Thanks,
Doug

 

[dpc]

Doug,

If the reactor is part of the drive, then it isn't covered by the Code, at least not directly.

If it is external, then Article 470 applies. I don't believe that overcurrent protection is specifically required by NEC for the reactor.

From a practical viewpoint, the drive protection should protect the reactor against a sustained overload and the upstream breaker should protect against internal short in the reactor.

Regards,

dpc