Circuit breaker, also known as air switch, automatic circuit recloser. When the working current exceeds the rated current, or short circuit and voltage loss occur, the circuit will be automatically cut off. Compared with other circuit breakers, vacuum circuit breakers are only different in arc extinguishing medium. There is no conductive medium in vacuum, which makes the arc extinguish quickly, so the distance between the moving and stationary contacts of the circuit breaker is very small. The VCB breaker uses the plasma to rapidly diffuse and extinguish the arc when the current in high vacuum flows through the zero point, so as to complete the purpose of cutting off the current.
1. The arc is extinguished in the sealed container, and the arc and hot gas are not exposed;
2. The contact gap is very small, only a few mm to 40 mm.
3. Short arcing time, low arcing voltage, small arcing energy, less contact wear and more allowable breaking times.
4. The inertia of the moving conducting pole is small and suitable for frequent operation;
5. Simple structure, small volume and light weight;
6. Low noise during operation;
7. There is no oil, so there is no danger of fire and explosion;
8. The contact part is completely sealed, so it is not easy to reduce the performance due to the influence of moisture, dust, harmful gas, etc. the breaking and closing performance is stable, the contact wear is small, and the service life is long.
1. It is easy to produce switching overvoltage. When the inductive current is cut off, the current will be cut off, resulting in higher overvoltage. Therefore, an overvoltage absorption device should be installed.
2. It is difficult to monitor the vacuum degree during operation;
3. The composite insulator is easy to accumulate dust in the operation of thermal power plant, so the environment of auxiliary power room should be relatively clean.