触头烧损对SF_6断路器介质恢复特性的影响

Dielectric Recovery Characteristics of SF_6 Circuit Breaker Considering Contact Burning Loss

为研究126 kV SF6断路器在多次切合补偿设备过程中的介质恢复特性,根据电流较小时电离不充分的特点,建立了SF6双温度电弧等离子体模型并将它应用到气流场计算中。根据多次开断过程中静弧触头的实际烧损情况,建立了灭弧室内电场及气流场的数学模型。采用流注理论临界击穿判据计算开关的介质恢复特性曲线并分析触头烧损对其影响。在此基础上,考虑动弧触头对静弧触头的挤压磨损,通过对灭弧室进行3维电场分析,分析了不同烧损情况对电场分布的影响。研究结果表明:触头烧损对临界击穿电压的影响十分明显,当开距为67 mm时,烧损角θ=60°的临界击穿电压与无烧损情况相比降低了180%;随着θ增大,静弧触头表面的电场畸变愈加严重,当烧损角θ=80°时,静弧触头表面某点的电场强度是无烧损情况下的8.91倍。根据以上分析,提出了改善SF6断路器中触头烧损对介质恢复特性影响的方法。

To obtain the dielectric recovery characteristics of 126 kV SF6 circuit breaker in repeatedly breaking andclosing processes, we established an SF6 double-temperature arc plasma model due to the fact that ionizing is inadequatewhen current is small, and then used it in flow field calculation. According to the actual burning losses of the breakers, wealso established mathematical models of electric field and flow field. In the light of the gas breakdown criterion in thestreamer theory, we researched the breakers＇ dielectric recovery characteristic curves as well as the influences of contactwear on them. Furthermore, taking the extrusion and attrition of static contact attributed to moving arc contact into con-sideration, we analyzed the effect of burning loss on the electric field distribution in interrupter through three-dimensionalelectric field simulations. Results illustrate that contact burning loss obviously impacts critical breakdown voltage. It isobtained that, for a pair of contact spaced by 67 mm, compared with non-burning loss condition, when burning loss angleθ is 60°, the critical breakdown voltage is reduced by 180%. Plus the electric field distortion gets more severe with in-creasing θ： when θ is 80°, the electric field intensity at a point on static arc contact could reach 8.91 times as much as thatof non-burning loss condition. Thereby, we proposed some methods to deal with the influences brought by contact burn-ing loss on the dielectric recovery characteristics.