Motor Contribution

[timm333]

Let’ say if there are ten motors on a bus fed by ten breakers then we have to consider the short circuit current contribution of all ten motors in order to size the bus.

What about the sizing of each breaker? Should the short circuit contribution of all ten motors be considered for the sizing of each breaker, or should the contribution of only one motor for each breaker?

 

[davidbeach]

Nine motors. No motor breaker has to interrupt the fault contribution of all ten motors.