Vacuum interrupter, also known as the vacuum switch tube, is the core component of the medium-high voltage power switch. The main function of vacuum interrupter is to make the medium and high voltage circuit cut off the power supply of the vacuum arc extinguishing chamber of ceramic shell through the excellent insulation of the vacuum inside the tube, which can quickly extinguish the arc and suppress the current, so as to avoid accidents and accidents.
Vacuum circuit breaker has a high insulating medium for arc extinction as compared to the other circuit breaker. The pressure inside the vacuum interrupter is approximately 10-4 torrent and at this pressure, very few molecules are present in the interrupter. The vacuum circuit breaker has mainly two phenomenal properties.
High insulating strength: In comparison to various other insulating media used in circuit breaker vacuum is a superior dielectric medium. It is better than all other media except air and SF6, which are employed at high pressure.
Strictly control the closing and opening speed of vacuum circuit breaker.
For the vacuum circuit breaker with a certain structure, the manufacturer has specified the best closing speed. When the closing speed of vacuum circuit breaker is too low, the wear of contact will increase due to the extension of pre breakdown time; When the vacuum circuit breaker is disconnected, the arcing time is short, and its maximum arcing time does not exceed 1.5 power frequency half wave. It is required that when the current crosses zero for the first time, the arc extinguishing chamber should have sufficient insulation strength. Generally, it is expected that the stroke of the contact in the power frequency half wave will reach 50% - 80% of the full stroke during circuit breaking. Therefore, the opening speed of the circuit breaker should be strictly controlled. As the arc extinguishing chamber of vacuum circuit breaker generally adopts brazing process, its mechanical strength is not high, and its vibration resistance is poor. Too high closing speed of circuit breaker will cause greater vibration, and will also have greater impact on bellows, reducing the service life of bellows. Therefore, the closing speed of vacuum circuit breaker is usually set as 0.6 ~ 2m / s.