Circuit breaker plus contactor on MV motor feeder
Circuit breaker plus contactor on MV motor feeder
(OP)
Hello everyone:
We have a 3MW 5.5kV DOL - started motor installed in a concrete plant. The process designer says that it may be started and stopped several times a day. So contactor shall be used to start and stop it. However, the client requires that vacuum circuit breaker will be used to protect the feeder circuit rated 1.5MW and above. Therefore, both circuit breaker and contactor ( without fuse) will be used on the feeder. Generally we use only one of them, CB or fused contactor, not both. Does somebody use this configuration on previous project? I wonder whether any manufacturer will provide such kind of switchgear? Is there any special protection consideration on this group of CB and contactor ?
Thanks,
Parkpower
We have a 3MW 5.5kV DOL - started motor installed in a concrete plant. The process designer says that it may be started and stopped several times a day. So contactor shall be used to start and stop it. However, the client requires that vacuum circuit breaker will be used to protect the feeder circuit rated 1.5MW and above. Therefore, both circuit breaker and contactor ( without fuse) will be used on the feeder. Generally we use only one of them, CB or fused contactor, not both. Does somebody use this configuration on previous project? I wonder whether any manufacturer will provide such kind of switchgear? Is there any special protection consideration on this group of CB and contactor ?
Thanks,
Parkpower





RE: Circuit breaker plus contactor on MV motor feeder
He is wanting to use a circuit breaker to protect the motor branch circuit?
Why not just use a motor relay in conjunction with your contactor and set it to protect both the motor and cables? This is the way I have typically seen it done.
RE: Circuit breaker plus contactor on MV motor feeder
You could easily feed this unit with a circuit breaker with overcurrent protection coordinated with the fuses, but that is not an arrangement I've seen in my experiences.
old field guy
RE: Circuit breaker plus contactor on MV motor feeder
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If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Circuit breaker plus contactor on MV motor feeder
If the customer insists on the breaker and the starter, I would just buy a standard breaker and a standard starter (including fuse) and have the vendor provide it as a package. It's a belt and suspenders approach, but it will work fine.
RE: Circuit breaker plus contactor on MV motor feeder
RE: Circuit breaker plus contactor on MV motor feeder
RE: Circuit breaker plus contactor on MV motor feeder
RE: Circuit breaker plus contactor on MV motor feeder
RE: Circuit breaker plus contactor on MV motor feeder
RE: Circuit breaker plus contactor on MV motor feeder
The post doesn't indicate the 5.5kV switch board fault level.
RE: Circuit breaker plus contactor on MV motor feeder
We try to persuade the client to adop the option of fused contactor. However, client still stick on the circuit breaker-contactor because of 55 degree ambient temperature. CB is used to replace fuse,and no fuse will be installed.
I hope we can find vendor to supply this kind of product.
RE: Circuit breaker plus contactor on MV motor feeder