Fault Withstand Ratings

[BigMotorGuy]

The concept of fault withstand ratings for a pump motor and associated power supply equipment was requested by a customer. I understand that junction boxes, feedthrough terminals, and power cabling needs to have a fault withstand rating, but does a motor need to have this rating? Since the motor is the end of the line, the only place a fault can occur is either in the motor windings (assuming an traditional induction motor) or the immediate stator leads or alternately upstream in the power supply system. In the case where the fault is in the motor, the stator and leads need to be replaced anyway and a fault upstream will not influence or cause harm to the motor which is downstream....so why would a motor need a fault withstand rating?

 

[davidbeach]

No fault withstand ratings for motors for the reasons you outline. There can be no meaningful value.

 

[BigMotorGuy]

Thanks davidbeach for your feedback. I just didn't make sense to me to rate a motor for fault withstand!