Generator circuit breakers are highly reliable switching devices installed between the generator and the step-up transformer. They protect the generator, the transformer, and the entire power plant from fault conditions, and also allow the generator to be safely connected to and disconnected from the grid.

GCBs operate under extremely demanding conditions: high currents, non-standard waveforms, and high Transient Recovery Voltage values. Therefore, they feature a reinforced design, fast-acting mechanisms, and special arc-quenching systems.

Purpose of Generator Circuit Breakers

Protection of the generator and transformer against short circuits in the grid.

Rapid disconnection during fault conditions.

Safe connection/disconnection of the generator to the grid.

Improved reliability and availability of the power plant.

Reduced duration of emergency outages (confirmed by GE Vernova).

Optimization of substation layouts and reduction of capital expenditures (conclusions by GE Vernova).

Minimum and Maximum Technical Specifications (General Ranges)

Generator voltage class: 15–25 kV (typical values for GCB)

Post-transformer line voltage: 200–800 kV (HV lines)

Generator capacity: 50–1,500 MVA (typical ranges for GCB)

Breakmaking current: up to 30–40 kA (depending on the series, data from GE Vernova)

Design types:

open-type,

as part of integrated modules with a disconnector, earthing switch, and instrument transformers,

SF₆-insulated, air-insulated, hybrid.

Cooling: natural or forced (up to 40,000 A with enhanced cooling)

Short-circuit current class: 63–300 kA (Hitachi Energy portfolio)

What We Can Supply and Provide

We supply generator circuit breakers of any brand—we select solutions tailored to the specific parameters of the generator, transformer, and substation layout.

We design generator connection assemblies, including GCBs, disconnectors, grounding switches, instrument transformers, and busbars.

We perform configuration, installation, commissioning, and maintenance.

We provide a warranty covering all stages—from equipment selection to commissioning.

Warranties and Liability

We ensure that the equipment complies with international standards, monitor the quality of deliveries, and guarantee the stable operation of the GCB as part of the power plant. Each stage is backed by an official warranty and technical support.