4160 motor amps

[dema]

Section 430 gives minimum motor amps to use in order to size conductors. However, the highest voltage given is 2300V. What should be done above 2300V? What amps should I use above 2300V? - long day.

 

[DGrant041]

Sorry no one has chimed-in until now.

I had a theory but I had to find it in black & white to back it up.

430.224 Size of conductors.
Conductors supplying motors shall have an ampacity not less than the current at which the motor overload protective device(s) is selected to trip.

430.6(A)(2) Nameplate values.
Separate motor overload protection shall be based on the motor nameplate current rating.

Why they said it that way is beyond me. . .

Good luck.

 

[kingpb]

A good estimate for motor current, is to take the Hp, and call it KVA, i.e. a 500 Hp motor, is 500KVA. Then simply do the math. 500KVA/(4.16KV*1.732) = 69.4A

That will be slightly high, not a lot, but better to be a little on the conservative side.

You can also look on various motor manufacturer websites, they publish data for MV motors, especially look at US Motors website.