OT: 753 VFD supply voltage.

Currently we are supplying a couple of hundred 753's with an input voltage of 435-440 VAC. Our utility company is going to correct this next month and we should get close to 480VAC afterwards.

Since our current supply is within +/- 10% of 460VAC. I do not think our drive performance will change, others think otherwise.

Does anyone know for sure?

It depends.

How close does your application push the drive to the speed limits of 0hz to 60hz.

Are your motors 460 volt or 480 volt?

Are there any line / load reactors in place and what %?

Does each drive have an inverter or are they in a common bus configuration?

From my understanding, you will be slightly undervolting the motor as the motor speed increases and the V/Hz curve calls for more than your input voltage. This will be close to 60hz.

You should be fine unless you're running at the ragged edge of overloading the motor as-is.