There are few switching situations that differ from the duties standardized for switching devices in transmission and distribution systems. One of these special situations are generator-current breaking. Generator circuit-breakers are breakers applied at a rated voltage matching the rated voltage of a generator.
They are located between the generator and step-up transformer. When no generator circuit-breaker is applied, an alternative solution is a circuit-breaker at the high voltage side of the step-up transformer.
The advantage of this solution is the less complicated simple high-current connection (generator bus duct) between generator and transformer.
The electrical and mechanical performances of a generator circuit-breaker are very different from standard MV distribution switchgear. The only standard available worldwide that covers specifically the requirements for generator circuit-breakers is ANSI/IEEE C37.013.