High-voltage circuit breakers are mainly divided into oil circuit breakers, oil circuit breakers, sulfur hexafluoride circuit breakers, vacuum circuit breakers, compressed air circuit breakers, etc. Their characteristics are as follows:

1. Multi-oil circuit breaker

The realization is simple, the price is cheap, but due to the large amount of oil, large volume, heavy maintenance workload and easy to explode and fire.

Multi-oil circuit breaker is a high voltage circuit breaker with insulating oil as the arc extinguishing medium and the main insulating medium. It has a simple structure and low process requirements, but it is large in size and uses more steel and insulating oil.

2. Less oil circuit breaker

Use less oil, the fuel tank structure is small and strong, with the characteristics of saving materials, explosion-proof and fire-proof. The low-oil circuit breaker is safe to use, greatly simplifies the power distribution device, is small in size, and is easy to transport.

Oil-less circuit breakers are simple in structure, have a long history of use, and have rich operating experience. They are still in the leading position in the power system. The oil-less circuit breakers produced in my country are indoor-type and 35kV and above are outdoor-type.

3.SF6 circuit breaker

Good electrical performance and higher fracture voltage. The operation, maintenance and overhaul of the equipment are very convenient, the overhaul period is long, and the breaking performance is good, and the floor space is small, especially the SF6 fully enclosed combination electric appliance can greatly reduce the floor space of the substation.

Generally speaking, due to the excellent performance of the SF6 insulating medium, the SF6 circuit breaker has many excellent characteristics.

• The fracture voltage is high. 220kV SF6 circuit breaker only needs a single fracture, so the structure is simple, and the manufacturing, installation, debugging and operation are convenient;
• Allows a large number of breaks and a long maintenance cycle;
• Good breaking performance, SF6 circuit breaker has large breaking current, short arc extinguishing time, no serious current interception phenomenon, and no reignition when breaking capacitive current;
• Not easy to catch fire, safer operation;
• Less area;
• The price is high.

4. Vacuum circuit breaker

Vacuum is used as the insulation and arc extinguishing medium. It is small in size and light in weight. However, it has high requirements for the process and materials of the arc extinguishing chamber. It can be operated multiple times, has good breaking performance, short action time, simple operation and maintenance, and high reliability. It is suitable for the characteristics of multiple operations in the power distribution system, and is widely used in 35kV and below systems.

5. Air circuit breaker

Air circuit breaker is also called compressed air circuit breaker. Use pre-stored compressed air to extinguish the arc. Compressed air is not only used as an arc extinguishing and insulating medium, but also as a driving force for transmission.

Air circuit breakers have large short-circuit capability, fast action time, small size, light weight, no fire hazard, but complex structure, expensive, and need to install compressed air systems. It is mainly used for 110kV and above. It has relatively long electrical parameters and open time In high-demand systems and occasions where large generator outlets require a large rated current and breaking circuit. In my country, it is usually used in large-capacity power systems of 110kV and above, and it has been basically replaced by SF6 circuit breakers.

6.SF6 fully enclosed combined electrical appliance (referred to as GIS)

It is the primary equipment other than transformers in the substation, including circuit breakers, isolation switches, grounding switches, current transformers, voltage transformers, arresters, busbars, inlet and outlet bushings or cable terminals, optimized and organically designed according to the system layout Combine into a whole.

Its main advantages are small footprint, less space, high operational reliability, long overhaul period, unaffected by external environmental conditions, and strong earthquake resistance. The main disadvantage is that it is expensive. At present, it has been used in more and more applications, mainly used in 110-500kV systems.