What is the working principle of VCB?
What is the working principle of VCB?
The vacuum circuit breaker (VCB) is a special type of circuit breaker. The arc extinguishing is carried out by vacuum. The operation and closing of the current-carrying contacts and the arc-related disturbances take place in the vacuum chamber of the circuit breaker. This is called a vacuum interrupter.
The vacuum used as an arc extinguishing device in a circuit breaker is called a vacuum circuit breaker. This is because the vacuum superior arc has high dielectric strength due to its decorative properties. Most of them are suitable for standard voltage applications. This technology has only been developed for high voltages. Although it is not commercially possible.
The current-carrying conductors and their corresponding arc interruptions operate within the vacuum chamber of the circuit breaker. This is called a vacuum interrupter. The center of this resistive symmetric ceramic insulator contains a steel arc chamber. The vacuum pressure inside the vacuum interrupter is maintained at 10–6 bar. The operation of the vacuum circuit breaker is mainly dependent on the material used for the current-carrying contacts.
Vacuum circuit breakers work on the principle that once the circuit breaker opens within the contact vacuum, the metal vapor in the contacts ionizes and an arc develops between the contacts. But the arc is easily extinguished. This is because fast electrons, ions and metal vapors are generated on the outside of the circuit breaker contacts, so dielectric strength can be reached quickly.
The most important feature of vacuum is that once an arc is generated inside the vacuum, it can be extinguished quickly due to the rapid rate of increase in the dielectric strength of the vacuum.
Vacuum circuit breaker contact material:
The vacuum circuit breaker contact material must meet the following characteristics.
- Contact resistance must be low.
- high density.
- The conductivity must be high to pass normal load current without any overheating.
- Thermal conductivity is increased to quickly dissipate large amounts of heat generated during arcing.
- The thermionic function should be high to allow disruption to start the arc.
- The trend must be to reduce welding.
- Low current chopping level.
- Resistant to high arc capacity.
- The boiling point should be high to prevent arc corrosion.
- The gas content must be given below to ensure a long service life.
JGGY Electrical mainly specializes for 6~42kV medium voltage electric (outdoor and indoor): load break switch, Disconnector, cutout fuse, Surge Arrester, vacuum circuit Breaker, ..
several years, with the strength, with good quality and pretty competitive price. Should you have any questions, pls do not hesitate to contact me.
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