2HP VFD question

Butch(OH) · Feb 28, 2013

I purchased an old H-D pedistol grinder for the shop with 12" x 2 wheels. The motor is 2HP 220 3 phase so I purchased one of the 2HP VFDs from fleabay to run it. While I am waiting for it to arrive Id like to run the wirng from the panel. I will be running 4 wires so as to properly seperate the ground and nuetral but dont know how to calculate the Amp draw single phase to size the wire and breaker? I will be running stranded wire in conduit if that makes any differance, about 25 feet from the main panel. Thanks!

Bob M · Feb 28, 2013

Assuming you will be using 220 volt single phase input, your VFD will draw 16 - 17 amps at full load. (Actual F.L. amps will be noted on the VFD nameplate and spec sheet.)

So a branch circuit run in #12 wire and protected with a 20 amp breaker should be adequate.

David G · Feb 28, 2013

You should have upsized the drive to a 3HP to use it on single phase input. I would recommend returning it before you open the box.

Butch(OH) · Feb 28, 2013

Thanks for the warning but I already asked about that. They said all drives below 5HP were rated with either single or three phase input.

Bob M · Feb 28, 2013

Butch - Not to worry - you should be fine with the 2 HP VFD.

Unless the grinder is going to be used for continuous, heavy grinding it will spend much (most?) of its time running only lightly loaded.

Dusty MI · Feb 28, 2013

I doubt you will need a neutral? And if you are using EMT/steel conduit that is your ground. That's down to just 2 wires.

evilboweivel · Mar 1, 2013

10 gauge wire
size the breaker by what the VFD says it needs

2HP VFD question

Butch(OH)

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Bob M

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David G

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Butch(OH)

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Bob M

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Dusty MI

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evilboweivel

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