What are the advantages and disadvantages of vacuum circuit breaker?

Vacuum circuit breaker is mainly used in high voltage switchgear. It refers to the circuit breaker that takes vacuum as arc extinguishing and insulating medium and performs current breaking and closing in vacuum container. Since its appearance in the early 1960s, with the improvement of the key technology and the development of new arc extinguishing chamber and operating mechanism, the technical parameters of vacuum circuit breaker are constantly improving, with excellent performance and outstanding advantages of rapid development, in the high voltage switch cabinet application is also more and more widely.

Advantages of vacuum circuit breaker:

1. Extinguish the arc in a sealed container, and do not expose the electric arc and hot gas. As a separate component, the arc extinguishing chamber is easy to install and debug. 2. Contact clearance is very small, generally about 10mm, small closing power, simple mechanism, long service life.

3. Short arc extinguishing time, arc low, arc energy is small, contact loss is small, more times of breaking.

4. The inertia of the moving guide rod is small and can be used frequently.

5. Small operating mechanism, small size, light weight.

6. Control power is small, switching operation noise is small.

7. Arc extinguishing medium or insulating medium without oil, no danger of live and explosion, safe.

8. The contact head is divided into completely sealed structure, which will not be affected by moisture, dust, harmful gas and reduce its performance. Reliable operation and stable on-off performance.

9. After the arc is broken, the medium between the fracture can recover quickly, and the medium does not need to be replaced.

10. Rings don't age and don't need replacing. In the service life, contact part does not need maintenance, inspection, generally up to 20 years or so without maintenance. Small maintenance workload, low maintenance cost, only for less oil circuit breaker about 1/20.

11. With multiple reclosing function, suitable for distribution network application requirements.

Disadvantages of vacuum circuit breaker:

1. When the inductive load or capacitive load is switched off, it is easy to cause overvoltage due to current closure, justification, reignition and other reasons, so the corresponding overvoltage protection should be taken.

2. The first investment price of the product is high, which is mainly determined by the professional production of the vacuum arc extinguishing chamber and the requirements of the reliability of the organization. If the operation and maintenance costs are considered comprehensively, the price is not high.

3. Because the contact structure of vacuum circuit breaker adopts butt type and the operating mechanism uses spring, it is easy to produce closing bounce and opening rebound. Closing bounce will not only produce high overvoltage, which will affect the stable operation of power grid, but also cause contact burn and even welding, especially in the inrush current of input group and short circuit closing. Brake rebound will reduce the distance between the contacts behind the arc, resulting in a re-breakdown behind the arc, the consequences are very serious.