winslowfam
Senior Member
- Location
- VA
Our client is designing a large conveyor system that requires 700HP to run. Because of limited physical space, they would like to run it with (2) 350HP motors, equally sharing the load. To save money, they are considering installing one 700HP soft start motor controller to run both motors. From what I've read, this is a common practice. In my review of the code, I know we must design for one (1) overload device per motor, and then it seems that if we follow the requirements of Art. 430.53(C) for it all, we should be fine. That Article specifies that the main short circuit protection rating for the motor controller must be sized based on Table 430.52 for the first motor (250% using inverse time breaker) plus add the FLA of the second motor...the conductors to each motor are protected by each overload device...and all components are to be listed, etc. My question is: for sizing the feeder breaker and conductors from the switchboard to the soft start, do I follow Art. 430.24 for the conductor sizing and then size my feeder breaker accordingly? or do I size the conductors as if it were one motor circuit...at 125% of FLA of 700HP?
Thanks!
Thanks!