MV(20kV) Vacuum circuit breaker and surge arrester

[varna]

Hi, i've got a tough dilemma regarding 20kV-Vacuum circuit breakers.
Do you possibly know about any requirements for installing surge arresters and where I have to mount them (i mean the surge arresters) on the bus-bar system or on every incoming bushing?

 

[dewone]

I've seen them on the breaker, and on the load side in the cells.

 

[rbulsara]

From top of my head, surge arrestors could help protect the breakers and/or loads from switching transients too, not only transients coming from utilities.

Utility companies do not want customer's surge arrestors on the line side of the incoming breakers,as they come in the way of performing a hi-pot tests on their feeders. (Surge arrestors could operate on hi-pot tests, Not good).

So I would place surge arrestors on the load side of the incoming bus or not provide any if the feeder breakers have them. For feeder breakers, I have seen mostly on the load side.

 

[Electic]

I would locate surge arrestors where the greatest exposure occurs (usually on the incoming or outgoing power line side of the breaker) or where the clamping will do the most good (nearest the device to be protected).

Within enclosed switchgear there may be limited space for surge arrestors, and you should seek the factory recommended location so as not to encroach on required phase spacing.

 

[prc]

Surge arresters with MV (22 &33kV) vaccum breakers is to avoid the trasient surges from vaccum switching to come to down line equipment.So it has to be on after CB, normally with a surge absorber capacitor.In India, when 33kV VCBs were originally used to replace oil CB,furnace transformers down line failed,some times on first switching, due to switching surges unique to VCB.