What Are The Components Of A Vacuum Circuit Breaker? What Are Its Characteristics?

Lv Pole Mounted Circuit Breakers is named because the arc extinguishing medium and the insulating medium of the contact gap after arc extinguishing are high vacuum; it has the advantages of small size, light weight, suitable for frequent operation, and arc extinguishing without maintenance. It is widely used.

Below, the editor will introduce to you "What are the components of the vacuum circuit breaker and what are the characteristics of the vacuum circuit breaker".

The vacuum circuit breaker mainly consists of three parts: vacuum arc extinguishing chamber, operating mechanism, bracket and other components.

1. Vacuum arc extinguishing chamber

Depending on the type of switch, there are ceramic vacuum arc extinguishing chambers with outer shielding covers, small vacuum arc extinguishing chambers with middle sealed cup-shaped longitudinal magnetic fields, and inner sealed glass bubble arc extinguishing chambers. The basic structure is as follows:

1) Airtight insulating shell

The airtight insulating system composed of an airtight insulating cylinder made of ceramic, glass or microcrystalline glass, a movable end cover, a fixed end cover and a stainless steel bellows is a vacuum sealed container. To ensure airtightness, in addition to the strict operating procedures in the sealing type, the material itself is also required to have low air permeability and internal degassing.

2) Conductive system

It consists of a fixed conductive rod, a fixed operating arc surface, a fixed contact, a moving contact, a moving arc surface and a moving conductive rod. The contact structure is roughly divided into three types: cylindrical contact, arc surface with a spiral transverse magnetic field contact slot, and longitudinal magnetic field contact. At present, this arc extinguishing chamber adopts longitudinal magnetic field technology and has a strong and stable arc extinguishing ability.

3) Shielding system

The shielding cover is an indispensable component in the vacuum arc extinguishing chamber. There are many types of shielding covers, such as the main shielding cover surrounding the contact, the bellows shielding cover, and the equalizing shielding cover. The functions of the main shielding cover are as follows: ① Prevent the products of the arcing process from splashing onto the inner wall of the insulating shell, thereby reducing the insulation strength of the shell. ② Improve the uniformity of the electric field distribution in the arc extinguishing chamber, which is conducive to reducing the local field strength and promoting the miniaturization of the vacuum arc extinguishing chamber. ③ Condensing the arc products and absorbing part of the arc energy is conducive to the recovery of the dielectric strength of the arc gap.

2. Operation mechanism

Different operating mechanisms are used according to different types of circuit breakers. Common operating mechanisms include spring operating mechanism (VS1), permanent magnet operating mechanism, and combined operating mechanism (VBD).

Other parts: chassis vehicle, insulating bracket, insulator, etc.

What are the characteristics of vacuum circuit breakers?

(1) Strong breaking capacity, up to 50kA; after breaking, the medium between the cracks recovers quickly, and there is no need to replace the medium.

(2) Small contact disconnection distance. The contact disconnection distance of a 10kV vacuum circuit breaker is only about 10mm. The required operating power is small and the action is fast, which can simplify the operating mechanism and extend the service life. Generally, no maintenance is required for about 20 years.

(3) Short arc extinguishing time, low arc voltage, small arc energy, small contact loss, and many interruptions.

(4) The moving guide rod has small inertia, which is suitable for frequent operation.

(5) When the switch is operated, the action noise is small, which is suitable for urban use.

(6) The arc extinguishing medium or insulating medium does not use oil, and there is no risk of fire or explosion.

(7) The contact head is a fully sealed structure, and its performance will not be reduced by moisture, dust and harmful gases. It works reliably and has stable switching performance. The arc extinguishing chamber is an independent component, which is easy to install and debug.

(8) During the service life of the vacuum circuit breaker, the contact part does not require maintenance and inspection. Even if maintenance and inspection are required, the time required is very short.

(9) The arc is extinguished in a closed container, and the arc and hot gas are not exposed.

(10) It has multiple reclosing functions and is suitable for the application requirements of the distribution network.