GCB in the 15,000 Amp range 1

[CuriousElectron]

Hi All,
Does anyone know what interrupting medium technology is used for high ampacity generator circuit breakers? I know for 5,000Amps and below typically vacuum is employed, but for high amperage applications, not sure if vacuum is still employed or perhaps SF6 or air blast technology?
Thanks,
EE

 

[edison123]

Who is making 15,000 amps breakers? The maximum I am aware of is 5,000 amps VCB.

Large generators have the breakers on the HV side of the generator step-up transformers.

 

[davidbeach]

I don't know who might make them, but there are lots and lots of generator breakers on the low-sides of the GSUs. We used to have a 20kA generator breaker. 20kA as a thermal rating, not an interrupting rating. Plant was decommissioned a few years ago and the breaker's gone. Got other generators, still in service than need 10kA breakers. That's not at all uncommon on a 1x1 combined cycle plant with a single GSU.

 

[LionelHutz]

Thermally rated only would be classed as switch then, not a breaker?

 

[davidbeach]

Pretty sure they have interrupting ratings as well. But since there are interrupting devices that have interrupting ratings around 20kA or so indicating that the 20kA was a thermal (continuous current) rating rather than an interrupting rating removes ambiguity.

 

[Gianoli]

They are all SF6 nowadays. Here is a link to one company's offerings:

Generator Circuit-breakers (GCB) | Hitachi Energy

Generator circuit-breakers protect important assets in power plants by clearing potential harmful short-circuit faults in transformers, and preventing damages.

www.hitachienergy.com

It used to be the domain of Airbast 50 years ago. There are still some around in service today.

 

[edison123]

Great info, Gianoli.

33,500 A ?

 

[wcaseyharman]

In the generators I work at, which are mostly gas and smaller steam turbines, plus some medium sized hydro, vacuum dominates up to a 5000A ampacity, above that it goes to SF6.
We had some magnablast air breakers, and some of the older hydros had air breakers, and even a couple of oil breakers, but those are all gone.
We still have some 4kV air contactors, but most everything in medium voltage has gone to vacuum.

 

[thermionic1]

Siemens makes (made?) a 15kV 8000A VCB.

ABB/Hitachi make SF6 GCB 10000A maybe?