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VFD/Motor Overcurrent Protection??? VFD/Motor Overcurrent Protection???
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Old 05-07-2012, 11:17 AM   #1
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Default VFD/Motor Overcurrent Protection???
Looking to install a 50HP VFD for a Chilled Water Pump. I'm a little old school and always protect my motors at 175% assuming I'm using a thermally protected breaker or time delay fuses. What I need to know is, can I use 125% due to the fact it will not be set up for full voltage start?

50HP 3-phase 65amps @460v
65amps @ 125% = 81.25amps or 90amp breaker/fuse #4wire.

or

65amps @ 175% = 113.75amps or 125amp breaker/fuse

your thoughts?

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Old 05-07-2012, 12:03 PM   #2
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GOT IT! NEC 430.126 and referance to 430.32. 125%

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