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RPC sizing for FP3NC


Diamond; Mod Squad
Mar 27, 2005
Northwest Indiana, USA
Anybody running an FP3NC from RPC? Wondering what size will do the trick. Machine says 22kva but that seems like it's way excessive.

I've gotten the info that rklopp ran his FP2NC with a 10HP RPC and only had a little issue with startup at high speeds, which he solved by putting a short delay between spindle startup and any rapid axis moves, but I think the FP3NC has a little larger main spindle motor, so maybe a 15HP RPC would be good?
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Connected loads are higher on the FP3NC.
Larger drive motor, and larger servo motors ( “Z” )

My main electrical cabinet on my FP3NC ( flip) data plate is marked “22 A “ (not KVA)
In my manual for the same machine in the general data the 380v connected load is called out as “ aprox 14.5 KVA”.

Cheers Ross
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Bear in mind that value is for 380 v supply. 220 supply to the transformer would then need about 38 amps of capacity.
Cheers Ross
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Ah, I probably misremembered the data plate. I only saw it that one time, haven't picked up the machine yet; hopefully Friday. It was probably 22A like yours, Ross, thanks. I'm a big dummy, haha. So yeah, more like 8.5 kva rated. That makes a lot more sense, I knew that sounded crazy high. Good, then I should be all set with the 15 HP RPC and that'll give me the ability to run a couple other items too. Maybe I'll finally get around to setting up the three phase breaker box I've had sitting around. The RPC should be here Friday also.

The kva should be the same no matter the voltage, I believe. Just the required amperage will increase at the lower voltage, like you noted.
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