MV protection - fuses vs. cbs

[buddy91082]

Anyone know of a document that describes the pros and cons of each for protection on medium voltage systems? Any opinions or experience?

Thanks.
b

 

[alehman]

Fuses - less expensive, fast acting, non-resettable, non-adjustable, low interrupting capacity, not controllable.

circuit breakers - opposite of above.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[ScottyUK]

Fuses can do one thing in response to a fault: melt. They don't allow use of unit protection schemes, and are next-to-useless if an earth faullt occurs on an impedance-earthed system. If allied with a contector then the fuse can provide s/c protection while a relay scheme provides more advanced protection functions for faults within the clearing capability of the contactor.


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If we learn from our mistakes I'm getting a great education!

 

[rbulsara]

Both have their places and both are extensively used on medium voltage systems. Selection of a technology or protection scheme depends on the application. You may want to narrow down your question to your specific application.

Other than that you can Google the nebulous subject.

Rafiq Bulsara

http://www.srengineersct.com

 

[Coward]

Another difference is current rating.
Fuses typically have maximum 400A rating while CBs have rating higher than that.

 

[purplepete]

My tuppence Fuses will limit fault currents (when applied correctly) to a much lesser value than ann equivalent CB.
But, there are some no-go zones for MV fuses (ie just above their rated value). Also, as stated CBs offer much more sophisticated protection. Mainly, cherck carefully the limitations on the fuses from a protection and an operating persepctive. In the end you hope for a smaller bang.