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240v in Star VS 420v in Delta, choosing VFD.

Kiwiturner

Plastic
Joined
May 28, 2019
400v in Star VS 240v in Delta, choosing VFD.

Hi all, I have picked myself up a new (to me) lathe for my home workshop, and am stuck with my 240v single phase home supply. So, I am shopping for a VFD.

The lathe motor is 1.5kw 420v 3 phase, currently in Wye but can be changed to Delta.

As I understand things, it can be run off a VFD that boosts the voltage to 400v 3ph in the current Wye config, or can be swapped to Delta and run off a straight 240v 1ph to 240v 3ph VFD. Please correct me if I am wrong on this.

My question is, is there a reason one would pick one way over the other, barring the slight price increase for the VFD that also boosts voltage?

Thanks in advance to anyone who can offer any insight.
 
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Typically if the motor is designed for "dual voltage", it will say so on the nameplate, i.e. 240V Delta, 420V star. You said it "currently in Wye but can be changed to Delta.". Does that mean the nameplate says that?

Also, the numers don't sound right, usually it's 240/415V, because 415 / the sq. rt of 3 (1.732) = 240 (239.61). So if someone made a motor that says "240/420V", I'd be immediately suspect of its quality...
 
Yes the nameplate lists busbar configs for both star and delta. As for the voltage anomalies, it is a Chinese motor circa 1974, so I'd personally forgive any slight error.
 








 
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