The conductive system of the arc extinguishing chamber consists of a fixed conductive rod, a fixed arc surface, a fixed contact, a moving contact, a running arc surface and a moving conductive rod. Among them, the fixed conductive rod, the fixed arc surface and the fixed contact are called the fixed electrode, the movable contact, the moving arc surface and the movable conductive rod are called the movable electrode. When the vacuum circuit breaker, the vacuum load switch and the vacuum contactor are closed, the operating mechanism closes the two contacts through the movement of the movable conductive rod and completes the circuit connection. In order to reduce the contact resistance between two contacts as much as possible and maintain stability and have good mechanical strength when the arc extinguishing chamber withstands dynamic stable current, a guide sleeve is arranged at one end of the dynamic conductive rod of the vacuum switch, and a set of compression springs are used to maintain a rated pressure between the two contacts. When the vacuum switch breaks off the current, the two contacts of the interrupter are separated and the arc is generated between them until the arc is extinguished when the current naturally passes zero.
3. Shielding System
The shielding system of vacuum interrupter is mainly composed of shielding barrel, shielding cover and other parts.
The main functions of the shielding system are:
(1) Prevent the contact from splashing a large amount of metal vapor and droplets during arc ignition, pollute the inner wall of the insulation case, and avoid the decrease of insulation strength or flashover of the vacuum interrupter case.
(2) Improving the electric field distribution inside the vacuum interrupter is beneficial to the miniaturization of the insulation shell of the vacuum interrupter, especially for the miniaturization of the high voltage vacuum interrupter.
(3) Absorbing part of arc energy and condensing arc products. Especially when short circuit current is interrupted in vacuum interrupter, most of the heat energy generated by arc is absorbed by shielding system, which is conducive to improving the dielectric recovery strength between contacts. The larger the amount of arc products absorbed by the shielding system, the greater the energy absorbed by the shielding system, which plays a good role in increasing the interruption capacity of the vacuum interrupter.
