Vacuum circuit breaker is named by its arc extinguishing media and the contact gap after the insulation medium are high vacuum; it has the advantage of small size, light weight, suitable for frequent operation, arc without maintenance, and it is popularly used in the power grid applications. Vacuum circuit breaker is 3 ~ 10kV, 50Hz three-phase AC system in the indoor power distribution device for industrial and mining enterprises, power plants, substations as electrical equipment protection and control purposes, especially for the requirements of no oil,less maintenance and frequent operation, circuit breakers can be installed in the middle cabinet, double layer cabinet, fixed cabinet as a control and protection of high voltage electrical equipment.
In a vacuum circuit breaker, two electrical contacts are enclosed in a vacuum. One of the contacts is fixed and one is movable. When the circuit breaker detects a dangerous situation, the movable contact pulls away from the fixed contact, interrupting the current. Because the contacts are in a vacuum, arcing between the contacts is suppressed, ensuring that the circuit remains open. As long as the circuit is open, it will not be energized.
Vacuum reclosers will automatically reset when conditions are safe again, closing the circuit and allowing electricity to flow through it. Reclosers can usually go through several cycles before they will need to be manually reset. Some types of vacuum circuit breakers must be reset every time the breaker trips. Before a manual reset, the person doing the resetting needs to check the system to determine what caused the unsafe conditions in the first place, and make sure that they have been addressed.