Rotary phase converter with PM-1440GT: motor doesn't spin at full speed

[gnachman]

Mark came over this morning and verified the lathe's motor was working and his theory was that the RPC was undersized.

I wired the VFD directly to the motor and it works great. This supports the theory that the RPC was the issue. I can live with this somewhat janky set up for a few weeks.

I will return the RPC and replace it with a 5 hp solid-state phase converter from Phase Perfect (which will take 2.5 weeks to arrive). I don't feel like rewiring every bit of electronics to work with the VFD—I don't want to get sucked into a big side project before I get to play around! @B2 when I'm ready to go all in on the VFD I will definitely read your document. It should make life a lot easier.

Thanks for everyone's help getting this sorted.

 

[mksj]

On the Phase Perfect, similar to an RPC the single phase legs are a pass through and should be connected to your transformer, the generated leg should not be connected to the control circuitry. There are also setting in the Phase Perfect if it is used to power a VFD, but for this size machine I would use a single phase input VFD. A lot less expensive then RPC/Phase Perfect.

If you decide at some later date you want to switch to a VFD, you can do what I call a basic VFD install which using your existing control system with some minor wiring changes, takes minimal time and cost.

PM-1440GT Basic Wiring Changes for using the Contactors to switch the VFD inputs

Sure does

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