Classification and characteristics of high voltage switches

High voltage vacuum circuit breaker 1. What are the types of high voltage switches? What are the differences between them?

Answer: Switchgear is an electrical device used to connect and disconnect circuits. High-voltage switches usually refer to switches of 10 kV and above, which include high-voltage circuit breakers, isolating switches and load switches.

The circuit breaker has a complete arc extinguishing device and is the most complete switch among high-voltage switches. It can meet normal working current and cut off short-circuit current. The isolating switch does not have an arc extinguishing device. It cannot be pulled closed under load, let alone cut off short-circuit current. The main functions of the isolating switch are: ① Isolating the power supply. When the electrical equipment is shut down for maintenance (such as the circuit breaker is shut down for maintenance), the isolating switch is used to isolate the power outage maintenance equipment from the power supply to form an obvious disconnection point to ensure the safety of the maintenance staff. ② Reverse operation. In the circuit of double busbar connection, the isolating switch connected to the busbar can be used to switch the power supply line from one set of busbars to another set of busbars without interrupting the power supply, so as to achieve non-stop power supply for busbar maintenance in double busbar connection.

In addition, the isolating switch can also open and close small current circuits (such as circuits less than 2 amperes).

The load switch has only a simple arc extinguishing device, which can only cut the normal working current but cannot cut off the short-circuit current. The load switch is often used in conjunction with a high-voltage fuse to cut off the short-circuit current and achieve short-circuit protection.

2.What kind of circuit breaker is a vacuum circuit breaker? What are its characteristics?

A: Vacuum circuit breakers use vacuum as arc extinguishing and insulating medium. All parts are sealed in a shell made of insulating glass and other materials, and the sealing between the moving contact rod and the moving contact is achieved by a metal bellows.

The empty circuit breaker has the following characteristics:

(1) Lightweight structure, small contact distance (10 kV, only 10 mm), fast action, easy operation, small size and light weight.

(2) The arc burning time is short. Because the contacts are in a vacuum, basically no arc occurs. A very small arc can generally be extinguished in half a cycle (0.01 seconds), so it is called a half-cycle circuit breaker. It is also independent of the current size.

(3) The contact gap dielectric recovers quickly.

(4) Long service life.

(5) It requires little maintenance and is fire and explosion proof.

At present, vacuum circuit breakers have been more and more widely used, especially 10kV circuit breakers. But when choosing, you should pay special attention to the quality of vacuum circuit breakers.