The composition of the vacuum circuit breaker

The main structure of the vacuum circuit breaker consists of a vacuum interrupter, an operating mechanism and an insulating support base frame, etc.

·Vacuum interrupter

According to the different types of switches, there are ceramic vacuum interrupters with outer shielding cover, miniaturized vacuum interrupters with cup-shaped longitudinal magnetic field sealed in the middle, and glass bubble interrupters with internal sealing. The basic structure is as follows:

①Airtight insulation system (enclosure)

The air-tight insulation system consisting of a gas-tight insulating cylinder made of ceramic, glass or glass-ceramic, a movable end cover, a fixed end cover, and a stainless steel bellows is a vacuum-tight container.
In order to ensure air tightness, in addition to strict operating processes in the sealing type, it is also required that the material itself has a small air permeability and internal air release.

②Conductive system

It consists of a fixed conductive rod, a fixed running arc surface, a fixed contact, a moving contact, a moving arc surface and a moving conductive rod. There are roughly three types of contact structures: cylindrical contacts, transverse magnetic field contacts with helical groove arc surfaces,
Longitudinal magnetic field contacts. At present, the longitudinal magnetic field technology is adopted, and this kind of arc extinguishing chamber has strong and stable arc breaking capacity.

③Shielding system

The shield is an indispensable element in the vacuum interrupter, and there are many types of shields around the contacts, such as main shields, bellows shields, and shields for voltage equalization. The role of the main shield is to:
a To prevent arc products from splashing on the inner wall of the insulating shell during the arcing process, thereby reducing the insulating strength of the shell. b Improve the uniformity of the electric field distribution inside the arc extinguishing chamber, which is beneficial to reduce the local field strength,
Promote the miniaturization of vacuum interrupters. c. Condensing the arc products, absorbing part of the arc energy, and contributing to the recovery of the dielectric strength of the back-arc gap.