喷口型面及尺寸对SF_6高压断路器介质强度恢复特性的影响

The Influence on Dielectric Strength Recovery Property in SF_6 Circuit Breaker by Altering the Dimension and Profile of the Nozzle in Arc Quenching Chamber

SF6高压断路器的喷口对断路器开断过程中吹弧气体的流动特性起着控制作用,从而成为灭弧室的心脏。该文以252kVSF6断路器为研究对象,研究了改变喷口喉部下游仰角、长度对灭弧室吹弧气体流动特性、介质强度恢复特性的影响;应用激波理论和拉伐尔喷口中流速与截面比的关系,研究了局部"放-收"型面及2段型面对吹弧气体的控制作用及对介质强度恢复速度的影响;比较了在不同的喷口尺寸及型面下介质强度的恢复速度,得出喷口下游的型面对开断过程中介质强度恢复速度影响显著的结论。这对SF6高压断路器喷口的优化设计及灭弧室小型化设计具有重要的实际意义。

The arc nozzle of SF6 circuit breaker is thought as the kernel of arc quenching chamber, because of its controlling effect on gas flow property during the breaking process. The 252 kV SF6 circuit breaker is taken as the investigation subject. The influences on gas flow and dielectric strength recovery properties, which are caused by altering the angle of elevation, the dimension and the profile of arc nozzle of SF6 circuit breaker, were investigated. According to the theory of shock wave and the relation between flow velocity（Mach number）and ratio of section area in Laval nozzle, the influences on controlling effect of gas flow and dielectric strength recovery properties, which are caused by local ＂expand-shrink＂ nozzle and＂two-segment＂ profile nozzle, were investigated. And the dielectric strength recovery properties of different profile and dimension of arc nozzle were compared. The result shows that the profile of arc nozzle affects remarkably dielectric strength recovery property during the breaking process. The conclusion is very valuable for the optimum design for arc nozzle of SF6 circuit breaker and miniaturization design for arc quenching chamber.