TD12-40,5/1250A Vakuumschaltkammer 35kV Vakuumröhre

Vacuum interrupters for ZN12, ZW7 and ZN23, also known as vacuum switch tubes, are core components of medium- and high-voltage power switchgear. Their main function is to use high-insulation media in a vacuum environment to realize the opening and closing of circuits, and quickly extinguish arcs when the current crosses zero, thereby safely and reliably cutting off power lines.

I. Basic structure and components

A vacuum interrupter is a sealed electro-vacuum device. Its typical structure mainly includes the following systems:

Hermetic insulating enclosure: Usually made of glass or ceramic, it is used to maintain the high vacuum state inside (usually below 10 Pa) and provide main insulation.

Conductive system: Consists of a static conductive rod, static contact, moving contact, moving conductive rod and so on. The moving contact is connected to an external operating mechanism through the moving conductive rod to realize opening and closing operations.

Contact system: It is the key part for generating and extinguishing arcs. The contact material of vacuum interrupters for circuit breakers usually adopts copper-chromium alloy (copper and chromium each account for about 50%). This material has high breaking capacity, high resistance to electric corrosion and good resistance to welding. The early contact structure was a simple cylindrical shape, while modern ones generally adopt longitudinal magnetic field cup-shaped structures to improve the ability to break large currents.

Shielding system: Mainly composed of shielding covers (cylinders) surrounding the contacts. Its functions include: preventing metal vapor generated during arc combustion from contaminating the inner wall of the insulating enclosure; improving the electric field distribution inside the interrupter; absorbing part of the arc energy and helping to condense arc products, thereby increasing the breaking capacity

Bellows: Thin-walled elastic elements made of stainless steel, welded between the moving conductive rod and the enclosure. Its core function is to maintain the vacuum seal inside the interrupter while allowing the moving contact to move linearly during opening and closing operations, and it is a key component to achieve high mechanical life.

II. Working principle

The working principle of vacuum interrupters is based on the excellent insulation and arc extinguishing performance of high vacuum media:

Closing the circuit: The operating mechanism pushes the moving conductive rod to close the moving and static contacts, and the circuit is conducted.

Generating arcs: When the charged contacts separate, the contact points shrink rapidly, and the current density increases sharply, causing the metal material to melt and evaporate into metal vapor. Under the action of a strong electric field, the metal vapor is ionized to form a vacuum arc.

Extinguishing the arc: The vacuum arc is maintained by the metal vapor evaporated from the contact material. When the alternating current naturally crosses zero, the arc is temporarily extinguished, and the metal vapor particles quickly diffuse and condense on the shielding cover. At the same time, the opening distance of the contacts increases, and the dielectric strength of the gap recovers rapidly, thereby preventing the arc from reigniting and completely breaking the circuit.

III. Main features and advantages

Vacuum interrupter technology has the following significant advantages:

Safe and environmentally friendly: Vacuum is used as the arc extinguishing medium, there is no fire or explosion risk, no toxic and harmful gases are generated, and there is no pollution during operation.

Excellent performance: Fast arc extinguishing speed, strong breaking capacity, long electrical and mechanical life.

Easy maintenance: Small size, light weight, compact structure, basically maintenance-free and reliable in operation.

Energy and material saving: Low energy consumption, small required operating energy and low material consumption.

IV. Application fields

As a core component, vacuum interrupters are widely used in the following fields:

Power system: Mainly used for vacuum circuit breakers in substations and power grid facilities, and vacuum load switches for end users of power grids, covering voltage levels of 10kV, 35kV and even higher.

Industrial field: Widely used in power distribution systems and motor control equipment in industries such as metallurgy, mining, petroleum, chemical industry and railway.