Can a circuit breaker be used instead of an Isolator?

[tomzie27]

Is it Ok to use a 1250A circuit breaker incorporated in the PSU in lieu of an external Isolator(Heavy duty, 1250A) in isolating a power supply unit from a substation.

Also what is the airgap between the contacts of an Isolator and that of a circuit breaker too?

 

[Marmite]

There's not enough information in your post to give an answer. If you are talking high voltage then an open circuit breaker alone may not be acceptable as a point of isolation for work on equipment downstream, depending on the HV Safety Rules in effect at your location.
Regards
Marmite

 

[Skogsgurra]

There are circuit breaker "trucks" that can be removed from the corresponding cabinet, which is then locked. They can be used as isolators. But a single CB may not be used - there is a need to see the "missing link" visually in most codes.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[AusLee]

i understand your question in 2 ways:

1. if you mean that is it enough to use the incorporated CB, or do you still have to buy an external unit, i think the answer is no you do not need to buy any more units and you can limit yourself to the CB on the PSU.

2. if you mean that a heavy duty isolator can replace a C.B. because it can open on full load and close on short circuit, then i think you cannot because after you close on a short circuit the isolator is toast unless there is a circuit breaker on the same line to interrupt this fault.

 

[oldfieldguy]

Many entities require a "visible air gap" for isolation for safety purposes. This translates to a knife switch or similar disconnect for isolation, or a truck-mounted circuit breaker that can be racked out of its cubicle and locked.



old field guy