How Much Do You Know about Vacuum Interrupters?

A vacuum interrupter is a medium that uses vacuum as an insulating medium and extinguishes the arc,Electric vacuum device with AC current breaking capability used in vacuum switchgear.Also known as vacuum switch tube, vacuum bubble, etc.

The vacuum interrupter is mainly used in the following equipment:vacuun circuit breaker,load switch,contactor,recloser,vacuum fuse,etc.According to voltage class,It can be divided into: low voltage (<3kv), medium voltage (3-24kv), high voltage (above 24kv).The vacuum interrupter is mainly composed of a moving conductive rod, a static conductive rod, a moving contact, a static contact, a bellows, a glass case and a shielding cylinder.Each part of the vacuum interrupter has corresponding functions:

The role of the insulating shell：

1. Sealed with other parts to form a vacuum shell,Ensure the high vacuum environment necessary for the work of the arc extinguishing chamber.

2. Keep the live poles of the switch isolated.

3. Assembly support for shielding systems and conductive loops.

The role of the conductive circuit and the installation interface；

1. Make the arc extinguishing chamber have the current conducting capacity specified by its technical parameters.

2. Make the arc chute installed in the switch reliably.

The role of electrodes and contacts:

1. Arc burns and extinguishes on the contact surface.

2.The electrodes provide the magnetic field that controls the arc.

The role of shielding cylinder:

1. Shields and absorbs arc builders and prevents contamination of insulating enclosures.

2. Balance the electric field distribution of the system and improve the insulation level of the arc extinguishing chamber.

The role of bellows:

1. Make the moving end electrode of the arc extinguishing chamber move within a certain range.

2. Maintain a high vacuum environment inside the arc chute.

Insulation sleeves, guide sleeves, getters and other accessories：

1. The insulating sleeve is mainly used to increase the creepage distance of the arc-extinguishing outdoor surface,The arc extinguishing chamber can work in relatively harsh conditions.Requirements: high dielectric strength, good aging resistance.

2. The guide sleeve is used to guide the movement of the moving conductive rod.High mechanical strength, wear resistance, good lubricity, high temperature resistance and aging resistance are required.

3. The getter is used to absorb the gas generated during the operation of the arc chute,Maintain a high vacuum inside the arc chute.Getters are generally found in all vacuum devices.

The vacuum interrupter is the core component of the circuit breaker.For AC circuits with a frequency of 50HZ,current has zero value 100 times per second,The brief time before and after the current zero-crossing,The metal vapor and electric field energy supporting the arc burning are insufficient to sustain the arc burning,Plasma particles in the arc spread rapidly,Rapid recovery of dielectric strength in vacuum gaps in microseconds.If the rising speed of the power frequency recovery voltage is less than the recovery speed of the insulation strength of the vacuum gap,the vacuum gap no longer broken down,and the circuit can be disconnected.

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