高频下真空灭弧室纵向磁场仿真

Axial Magnetic Field Simulation of Vacuum Interrupters at High Frequency

真空灭弧室是机械式高压直流断路器的核心部件,为了有利于熄灭电弧,开断直流电流时,通常利用人工过零技术,在直流电流上叠加高频震荡电流,使得开断故障电流过零。由于直流断路器开断电流为高频电流,灭弧室间隙磁场分布对真空断路器的开断有着决定作用,通过建立三维真空灭弧室触头有限元模型,分析计算高频情况下的真空灭弧室的磁场分布情况。结果表明:高频情况下触头间隙磁场大小以及磁场滞后时间受到严重影响,触头间隙纵向磁场大小与平板触头产生效果类似,这对断路器开断效果很不利。

The vacuum interrupters is the core component of the mechanical high-voltage DC circuit breaker.In order to facilitate the arc extinguishing,when the DC current is interrupted,the artificial zero-crossing technology is usually used to superimpose the high-frequency oscillation current on the DC current,so that the fault current crosses zero.Since the breaking current of the DC interrupters is a high-frequency current,the gap magnetic field distribution of of arc extinguishing chamber has a decisive effect on the breaking of the vacuum circuit breaker.By establishing a finite element model of the three-dimensional vacuum interrupters contact,the magnetic field distribution of the vacuum interrupter under high frequency conditions is analyzed and calculated.The results show that the contact gap magnetic field and the magnetic field lag time are seriously affected under high frequency conditions.The axial magnetic field of the contact gap is similar to that of the flat contact,which is unfavorable for the breaking effect of the interrupters.