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Can we use 400V motor with Altivar using 500V AC power supply?

Yes, it is possible, but there are certain conditions.
Combination of 500V supply voltage and 400V rated motor is not very well optimized when it comes to ATV selection.

First, due to 500V supply, the ATV selection requires use of 690V class drive. (ATV....Y). Drives ATV...N4 are usually limited to 480V supply and therefroe cannot be used at 500V.
Seconds, ATV...Y drives (because they are rated for 690V) cannot be selected based on motor power, because there is great difference in motor rated current when motor rated voltage is 400V, 500V or 690V at the same motor power
From this reason, ATV...Y must be selected to provide maximum continuous current equal or greater than motor rated current at 400V.

Example: 355kW motor, U=400/690V (D/Y), In=605/346A (D/Y). Supply voltage 500V
ATV71HC50Y although it is 500KW drive, it cannot be used for this motor. ATV71HC50Y is rated for 500kW only if supply voltage and motor rated voltage is 690V
MAx continuous output current of  ATV71HC50Y is 590A (catalog value for the lowest votlage which is 500V). This current is not enough for motor with rated current 605A. ATV71HC63Y is therefore the only solution.

Summary:
If possible try to avoid combination 500V supply and 400V motor because the drive selection is not ideal and highly likely will lead to drive oversizing. Try to use either 500V motor or lower the supply network below 480V (e.g. using a transformer) to be able to use ATV...N4 drive that offers better selection ratio for 400V motor.
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