I am trying to figure out how to do calculations with the values on a motor rating plate and to get the apparent power I have to use the formula: "line voltage x line current x √(3) = apparent power". When I multiply that with the power factor and the efficiency I get a value that is a kW more than the power at the shaft. Why is this the case, am I doing something wrong?

 

Shaft power (HP or kW) is a mechanical value expressing torque at the base motor speed. Anything you calculate base on electrical values are true for worst case scenario from an electrical standpoint only. Back-tracking electrical values to attain the mechanical values is an approximation.

83A x 460V x 1.732 = 66.13kVA apparent power.

 

(66.13 KVA x PF O.9 x EFF. 0.954 ) / 0.746 =76.1 HP