According to the arc extinguishing medium used by the circuit breaker, it can be divided into the following types:

1. Air circuit breaker

The air circuit breaker uses compressed air as the arc extinguishing medium, which is fireproof, explosion-proof, non-toxic, non-corrosive and easy to use. The air circuit breaker belongs to the other-energy circuit breaker, which is cooled by blowing the arc with compressed air. When the arc reaches zero, the ions in the arc channel are quickly blown away or compounded to realize arc extinction. The air circuit breaker has strong breaking capacity and short breaking time, but its structure is complex, its process requirements are high, and its non-ferrous metal consumption is high. Therefore, the air circuit breaker is generally used in 110KV and above power systems.

2. Oil circuit breaker

The oil circuit breaker uses insulating oil as arc extinguishing medium. It can be divided into multi-oil circuit breaker and low-oil circuit breaker. In the multi-oil circuit breaker, oil is not only used as the arc extinguishing medium, but also as the insulating medium, so the oil consumption is large and the volume is large. In the oil-less circuit breaker, oil is only used as arc extinguishing medium, so the oil consumption is small, the volume is small, and the steel consumption is small.

3. Vacuum circuit breaker

Vacuum circuit breaker is used to extinguish arc in high vacuum. The arc in vacuum is formed in the metal vapor evaporated from the electrode when the contact is separated. The ions and electrons in the arc diffuse rapidly to the surrounding space. When the arc current reaches zero, and the number of particles between the contacts disappears due to diffusion exceeds the number of particles generated, the arc cannot be maintained and extinguished. The vacuum circuit breaker has strong breaking capacity, short breaking time, small volume, small occupied area, no noise, no pollution, long service life, frequent operation and long maintenance cycle. At present, vacuum circuit breakers have gradually been widely used in distribution systems in China. In addition, there are magnetic blow-out circuit breakers and self-produced gas circuit breakers, which have the advantages of fire protection, explosion protection and convenient use. However, the general rated voltage is not high and the breaking capacity is not large. It is mainly used as a circuit breaker for power distribution.

4. Sulfur hexafluoride (SF6) circuit breaker

SF6 circuit breaker uses SF6 gas with excellent arc-extinguishing capacity and insulation capacity as the arc-extinguishing medium, which has the advantages of strong breaking capacity, fast action, small volume, etc., but the metal consumption is high and the price is expensive. SF6 circuit breakers have developed rapidly in recent years and are widely used in high-voltage and ultra-high-voltage systems. In particular, SF6 circuit breaker is the main body of the closed combined electrical apparatus, which is an important development direction of high-voltage and ultra-high-voltage electrical apparatus.