Main Structure
Vacuum circuit breakers mainly consist of three parts: a vacuum interrupter, an electromagnetic or spring operating mechanism, and a support frame.
According to different switch types, there are externally shielded ceramic vacuum interrupters, internally sealed cup-shaped longitudinal magnetic field miniaturized vacuum interrupters, and internally sealed glass bulb interrupters. Their basic structures are as follows:
① Airtight Insulation System (Shell): The airtight insulation system, composed of an airtight insulating cylinder made of ceramic, glass, or microcrystalline glass, a moving end cover plate, a fixed end cover plate, and a stainless steel corrugated pipe, forms a vacuum-sealed container. To ensure airtightness, in addition to strict operating procedures in the sealing type, the materials themselves must have low permeability and minimal internal gas release.
② Conductive System: Consists of a fixed conductive rod, a fixed arc-running surface, a fixed contact, a moving contact, a moving arc-running surface, and a moving conductive rod. There are roughly three types of contact structures: cylindrical contacts, transverse magnetic field contacts with spiral groove arc-running surfaces, and longitudinal magnetic field contacts. Currently, longitudinal magnetic field technology is used, and this type of interrupter has a strong and stable arc-breaking capability.
③ Shielding System The shielding cover is an indispensable component of a vacuum interrupter, and there are various types, including the main shielding cover surrounding the contacts, the bellows shielding cover, and the equalizing shielding cover. The functions of the main shielding cover are: a) to prevent arc products from splashing onto the inner wall of the insulating shell during the arcing process, thereby reducing the insulation strength of the shell. b) to improve the uniformity of the electric field distribution inside the interrupter, which helps to reduce the local field strength and promotes the miniaturization of the vacuum interrupter. c) to condense arc products, absorb some of the arc energy, and help restore the strength of the post-arc gap medium.
Post time: Nov-13-2025
