Why would an AC motor running on 480V power rated for .96 FLA pull 1.2 AMPs if it's not overloade?

Question

Why would an AC motor running on 480V power rated for .96 FLA pull 1.2 AMPs if it's not overloade?

Answer 1

Steady State current of 1.2 amps. Could be due to the machine wear, or fluctuating voltage or an unbalanced line to line.

Machine wear: bearings, poor coupling, load is greater than what it was maybe due to friction.

Fluctuating voltage: Nominal 480VAC could drift from 440VAC to 490VAC.

Unbalanced Line: voltage line to line A-B, B-C, A-C may not be within 10% of each other.



If the motor is started and stopped a lot can contribute to wear and tear. AC motors like to be on all the time vs started then stopped and started again.

Answer 2

If the motor is running above .96 FLA at rated voltage 480V then it would indeed be in an overload condition.

if it had a service factor of 1.15 (mentioned on nameplate SF) it would be able to run at 15% above 0.96 A satisfactorily.A decrease in rated voltage say 460V would increase the FLA (Full Load Amps)value.A defective bearing would give you the condition you mention.

Answer 3

Starting current maybe...