Adjustable-Speed Drive OCPDs

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gboynton1

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A 30 HP continuous-duty motor (460/3/60/40 FLA) is drive (w/integral pypass) supplied. I believe that if a NEMA 3 FVNR starter were used it would be permissible to protect the #6's selected with a 90/3 standard rated breaker.

It seems that the drive, however, would require #3's to be afforded protection by that same 90/3 breaker.

Any code thoughts or industrial experience on this topic is appreciated. gb_
 
A drive should eliminate or greatly reduce high start up currents.

Also do not forget you must supply the drive based on it's rated current regardless of the motor size.

If you have a 50 HP drive supplying a 25 HP motor you have to supply the drive like it had a 50 connected to it.

430.2 (2002)
 
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