South Korean Voltage for Squirrel Cage Motors

The combination of 400 V and 60 Hz sounds unfamiliar. Could you please recheck, and also confirm the rpm and performance on the pump curve?

Yes, the R.O.K. is 400V (380V) and 60Hz. It's an oddball on the world voltage grid.

Yes, but what is your favorite color?

With the frequency design of the motor being 60Hz, giving a 460V motor only 400V will drop the peak torque by the square of the voltage reduction. So 400/460 = .87, so the peak torque will be only 75% of the motor's original design. But running torque will drop linearly with the votlage drop, and if it is a centrifugal pump, you likely do not need peak starting torque. So you can assume that the motor shaft HP will drop to 87% and be relatively accurate. That means a 75HP motor will put out about 65HP continuously. That's running a little on the ragged edge of the motor performance, and it will mean increased slip, so more current, thus more heat. I would opt for the 100HP motor if I were you.

Great answer, just what I was looking for. We are using VFD's so we have some measure of control on FLA. Of course, there would be an additional concern running the 75 down to 25 htz at 400 V right? We have a recirculation mode that will make up about 50% of the operational use of the pump running anywhere from 25-35 Htz.

Thank you,

JT