Location of high voltage devices

[samreen]

what will the ideal location of high voltage compononet(circuit breaker,isolator ,current transformer and voltage trasnformer).
some times curent transformer are placed before circuit breaker and sometimes after CB..
Is there any rule for positioning high voltage component??

 

[davidbeach]

Breaker should always be in the zone of protection. So if you have both line and bus protection, the line CT will be on the bus side of the circuit breaker and the bus CT will be on the line side of the circuit breaker.

 

[NCTHAI]

Typically, first equipment coming in sequence is LA - in any type of feeder; Next is communication equipments (If Line feeder and PLCC installed), CVT / CT / Voltage measurements, then CT (to include all other isolators / earth swithces)in zone of protection and then earth switch, isolator, CB as required and based on configuration of circuit / feeder.

 

[slavag]

Hi Samreen.
Is depend on the local rules.
For example: in our application, we placed CT after CB only ( toward to the line), one core to BBP ( 87B) is protected CB and bus disconnectr, one core for line/trafo, etc protection, usually is overlapping style.
But last time, in few projects, we see one CT before, one after CB, take in account is additional price.
In one very old application, mnf used one CT after line DS for the BBP (87B).
Best Regards.
Slava