Directional Protection on a Motor

[MD88]

Hi guys, I've noticed that on Multilin M60 and other high end motor protection relays, directional overcurrent for phase and ground is available... the only scenario I can see wanting this is if there's a fault on another feeder off the same bus and the motor starts feeding it, you would block tripping on the motor feeder breaker until the faulted feeder is cleared...?

Thanks

 

[templdl]

Hi guys, I've noticed that on Multilin M60 and other high end motor protection relays, directional overcurrent for phase and ground is available... the only scenario I can see wanting this is if there's a fault on another feeder off the same bus and the motor starts feeding it, you would block tripping on the motor feeder breaker until the faulted feeder is cleared...?

Thanks

Since 3ph motors rely on a given phase sequence that determines the direction that they rotate there would be devastating consequences should one of the phases as provided from the POCO be reversed.

 

[MD88]

I agree, but phase reversal is a separate protective function...