Large capacity circuit breaker

The vacuum arc extinguishing chamber uses a pair of contacts in vacuum to achieve the connection and disconnection of power circuits, using high vacuum as the insulating medium. When the circuit breaker receives a disconnection signal, the moving contact moves, the moving and stationary contacts separate, and an arc is burned between the contacts. As the distance between the contacts increases, the plasma of the vacuum arc quickly spreads outwards under the action of the magnetic field. After the current crosses zero, the medium in the contact gap quickly changes from a conductor to an insulator, and the current is disconnected, ending the disconnection.

Large capacity refers to a circuit breaker with a high rated current and high short-circuit breaking level. The current is generally 5000-10000A, and the short-circuit breaking level is 50-100kA.

The GE VB1 Power/Vac circuit breaker is a typical high-capacity circuit breaker, with a short-circuit breaking current of up to 63kA and a rated current ranging from 1250 to 5000A. It is equipped with a PV switchgear. Widely used in power plants.

The Eaton VCP-W63W vacuum circuit breaker can operate reliably at high sustained current levels, with a rated current of up to 4000A using natural air convection cooling and a rated current of up to 6300A using built-in fan cooling under overload conditions.

Rated voltage: 12kV

Rated current: 4000A naturally air-cooled, 6300A forced air-cooled

Rated breaking capacity: 63kA

Maximum closing capacity: 160kA

Rated short-circuit duration: 3s

1-minute power frequency withstand voltage (effective value): 42kV

Lightning impulse withstand voltage (peak): 75/95kV

The VCP-W63W circuit breaker adopts 180mm diameter plum blossom contacts, circular static contacts, and 4-120 * 10 copper bars. Open insulator pillar structure, with a gap in the middle of the contact arm, and heat dissipation grooves cut on both vertical surfaces. GPO-3 arc resistant insulation plates are used between phases to ensure voltage resistance requirements. Equipped with circuit breaker compartment units for easy cabinet use. The unique contact box, guide rail, and valve system ensure high fitting accuracy and temperature rise meets standard requirements.  

Siemens 3AH3 vacuum circuit breaker rated voltage: 17.5kV rated current: 4000A naturally air-cooled, 5000A forced air-cooled rated breaking capacity: 63kA maximum closing capacity: 160kA

The 3AH3 circuit breaker adopts a floor standing structure, which is convenient for moving on the ground. Each phase is arranged vertically with 2 sets of duckbill contacts, which is conducive to heat dissipation. With the same insulator supported structure, the increased arc extinguishing chamber has high current carrying and short-circuit breaking capacity, as well as high peak withstand current.

Generator circuit breaker is a protective device installed between the generator and the step-up transformer. It not only provides protection for the generator and main transformer, but also plays a positive role in starting, stopping, maintaining, and increasing operational flexibility and reliability of the generator set.

Due to the special working environment of generator protection circuit breakers, their reliability is extremely high, with rated parameters reaching 17.5kV/10000A/80kA. The outlet circuit breaker of large capacity vacuum generators can be applied to generators up to 450MW.

The contact pressure of the vacuum bubble (arc extinguishing chamber) of a 50kA vacuum circuit breaker is 6000N, and the contact pressure of a 63kA arc extinguishing chamber reaches 9000N. Generally, the contact pressure of a 31.5kA circuit breaker is only 3000N. Therefore, the energy requirements for the operating mechanism of a 63kA circuit breaker are very high, and sufficient energy is needed to ensure that the contacts can withstand the contact spring pressure and achieve proper closing, as well as to resist the electric force of the closing short-circuit current. Therefore, the force and stroke of the closing spring of the operating mechanism need to be sufficiently large, resulting in a very strong overall strength of the operating mechanism to ensure a mechanical life of 10000 cycles.