真空灭弧室内部屏蔽罩间隙雷电冲击击穿特性的面积效应

Area Effect on Breakdown Characteristics of Shield Gap in Vacuum Interrupter under Lightning Impulse Voltage

随着真空灭弧室电压等级的提升,其内部屏蔽罩间隙的尺寸增加将产生击穿面积效应,这将成为制约真空灭弧室绝缘性能的关键因素之一。本文研究了真空屏蔽罩间隙在不同间距条件下雷电冲击击穿特性的面积效应,实验中采用了三种直径的典型屏蔽罩结构,直径分别为40、60和80 mm,电极材料为不锈钢。结果表明,在恒定间距条件下,随着有效面积的增加,真空屏蔽罩间隙的绝缘强度呈下降趋势,并且下降速度逐渐增大。当间距增大时,一方面任意有效面积下屏蔽罩间隙的击穿电压显著提升;另一方面,由于有效面积的增大对击穿电压的削弱作用逐渐降低。本文的研究结果不仅可以指导真空灭弧室内部屏蔽罩间隙的绝缘设计,也可以为具有不同电极结构真空间隙的绝缘评估提供理论依据。

With the voltage level increase of vacuum interrupters,the breakdown voltage of the internal shield gap with large size will have area effect,which is one of the key factors restricting the insulation performance of vacuum interrupters.The area effect on the breakdown characteristics of shield vacuum gaps with different gap distances under lightning impulse voltage is investigated.Shield electrodes with three diameters of 40,60 and 80 mm are used.The electrode material is stainless steel.The experimental results reveal that,under a constant gap distance,with the increase of effective area,the dielectric strength of shield vacuum gap shows a decrease trend and the descent speed gradually increases.When the gap distance increases,the breakdown voltage of shield gap is significantly improved under any effective area,and the weakening effect of increasing effective area on the breakdown voltage gradually decreases.The research can not only guide the insulation design of the shield gap in vacuum interrupters,but also provide a theoretical basis for the insulation estimation of vacuum gaps with different electrode structures.