The generator main circuit breaker (GMCB) simplifies plant operation by eliminating the need for transferring auxiliary power supplies during startup. It eliminates the starting transformer and associated circuit breakers and isolates the generator if a unit trips or a fault occurs.
- Simplified Construction: The breakers feature a simplified contruction that minimizes the number of component parts. The system varies from the basic model which consists of a circuit breaker and a disconnecting switch only, to the fully-equipped model which also includes start-up disconnecting switch, current and voltage transformers, earthing switches, lightening arresters and surge capacitors.
- Direct coupling to Isolated Phase Bus (IPB) Two methods for coupling to IPB are available, site welding and flexible boots.
- Continuous current rating up to 22,000A natural cooling and 44,000A forced air cooling.
- Short-circuit withstand current up to 125kA (up to 280kA short-time current for Load Break Switch design).]
- The circuit breakers use single pressure puffer type interrupters, operated by three-phase gang operated hyraulic mechanism.
- GMCB for pumped storage power plants can be equipped with Phase Reverse Disconnecting Switch and Electrical Braking Switch.