High voltage is mainly divided into oil circuit breakers, sulfur hexafluoride circuit breakers, compressed air circuit breakers and so on. Their characteristics are as follows:
1. Oil circuit breaker
Oil-type circuit breakers are high-voltage circuit breakers 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.
Oil circuit breakers are simple in structure, have a long history of use, and have rich operating experience. They are still in the dominant position in the system. The oil-less circuit breakers below 20kv produced in my country are indoor-type, and 35kv and above are outdoor-type.
2.sf6 circuit breaker
Good 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 electrical appliance can greatly reduce the floor space of the substation.
Generally speaking, due to the excellent performance of the sf6 insulation medium, the sf6 circuit breaker obtains 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 period;
● Good breaking performance, sf6 circuit breaker has large breaking current, short arc extinguishing time, no serious current interception, and no reignition when breaking capacitive current;
● It is not easy to catch fire, and the operation is safer;
● Occupies less land;
● The price is high.
3. Vacuum circuit breaker
The vacuum is used as the insulation and arc extinguishing medium, which 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 the power distribution system with multiple operations, and is widely used in 35kv and below systems.
4. Air circuit breaker
Air circuit breakers are also called compressed air circuit breakers. 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, etc., mainly used for 110kv and above. The electrical parameters and breaking time are relatively short. In high-demand systems, and occasions where large generator outlets require a large rated current and breaking circuit. In our country, it is usually used in large-capacity power systems of 110kv and above, and it has been basically replaced by sf6 circuit breakers.
5.sf6 fully enclosed combined electrical appliances (gis for short)
It is the primary equipment other than transformers, including circuit breakers, isolating switches, grounding switches, current, lightning arresters, busbars, inlet and outlet bushings or cable terminals, optimized and designed according to the system layout and organically combined into a whole.
Its main advantages are small footprint, less space, high operational reliability, long maintenance cycle, unaffected by external environmental conditions, and strong earthquake resistance. The main disadvantage is that it is expensive. At present, more and more applications have been obtained, mainly used in 110-500kv systems.