Selection Principle and Empirical Data of Mechanical Parameters of Vacuum Circuit Breaker (2)
2024-09-09 11:01:49
5. Closing speed
Since the static withstand voltage level of the vacuum interrupter at the rated opening distance is relatively high, the closing speed of the vacuum circuit breaker is significantly lower than the closing speed. In order to minimize the electrical wear of the contacts due to breakdown during the closing process, and to avoid contact welding, it is necessary to have a certain closing speed, but an excessively high closing speed not only increases the closing speed of the operating mechanism At the same time, the closing impact of the vacuum interrupter is increased, which greatly reduces its service life. Under normal circumstances, the closing speed of the 10kV vacuum circuit breaker is 0.4-0.7m/s, and it can be 0.8-1.2m/s if necessary.
6. Contact closing bounce time
The closing time of the vacuum circuit breaker is an important indicator to measure the performance of the vacuum circuit breaker, which is related to the contact bounce pressure of the circuit breaker, closing speed, opening distance and the contact material of the vacuum interrupter. At the same time, it is also related to the structure of the arc extinguishing chamber, the structure of the circuit breaker and the installation and debugging. The smaller the bounce time of the contact when closing, the better its performance. The longer the bounce time, the more serious the electrical wear of the contact, and it is easy to generate closing overvoltage. When closing the short-circuit current or capacitor, the thermal stability test will lead to contact In addition, the longer the single jump time of the contact closing, it will seriously endanger the service life of the bellows of the arc extinguishing chamber. The closing bounce time of the vacuum circuit breaker of the head material can be relatively large, but it should not exceed 5ms.
7. Three-pole synchronicity
The three-pole synchronicity of the vacuum circuit breaker indicates the degree to which the three poles are not closed or separated at the same time. Since the opening and closing synchronicity is relative and the value is not very different, generally only the three-pole closing synchronicity is examined. A circuit breaker with poor synchronization of three poles will seriously affect the breaking capacity of the switch, and it is easy to generate too long arcing time. Due to the fast switching speed of the circuit breaker, the opening distance is small, and it is not easy to meet the requirements of participation through accurate debugging. It is not difficult, a share stipulates that the contract period should not exceed 1ms.
8. Coaxiality of moving and static contacts
The coaxiality of the dynamic and static heads has specific requirements for the vacuum interrupter and can be guaranteed by the manufacturing process. Whether the arc interrupter is installed on the operating mechanism can ensure its coaxiality, and the type and installation process of the operating mechanism. There is a direct relationship. For the county-mounted mechanism, the coaxiality mainly depends on the operating mechanism. For the floor-mounted machine, the influence on the coaxiality is also great. During the installation process, the arc extinguishing chamber must be prevented from being subjected to shearing force. And the effect of shearing force, the coaxiality is generally required to be no more than 2mm.