Let us talk about the breaking process of the vacuum circuit breaker can be divided into three key stages, as follows:
1. Opening process
Arc striking stage (0~3mm)
When the contacts are separated, the arc current quickly changes from the concentrated type to the diffuse type. This stage is crucial to the breaking performance. When the current passes through zero, the insulation strength between the contacts is quickly restored to complete the initial breaking.
Arc extinguishing stage (3~8mm)
When the contacts are separated to 3~4mm, the arc has completely turned into a diffuse type, and the arc extinguishing effect is best at this time. The opening spring is the main power source, pushing the contacts to separate quickly to form an optimal arc extinguishing distance of 3~4mm.
2. Arc extinguishing principle
Vacuum environment destruction: At the moment of contact separation, the vacuum in the vacuum arc extinguishing chamber is destroyed, the arc loses its energy source, and is quickly extinguished.
Magnetic field assistance: The contact is designed with a spiral groove or magnetic field structure to make the arc rotate at high speed (longitudinal or transverse magnetic field).
3. Key parameters
Arc extinguishing time: The entire breaking process is usually completed within a few milliseconds, ensuring high reliability and electrical performance.
Breaking capacity: The rated short-circuit breaking current (such as 10~12 times the rated current) is used as an indicator to reflect the ability of the vacuum circuit breaker to withstand short-circuit faults.
Vacuum circuit breaker achieves efficient arc extinguishing by quickly separating contacts, destroying the vacuum environment, and using magnetic field assistance. Its design focuses on optimizing the contact spacing (3~4mm) and arc extinguishing time control to ensure the safe and stable operation of the power system.
