500kV断路器断口电容及介损测量影响因素研究

Study on Influencing Factors of Measuring Break Capacitance and Dielectric Loss of 500kV Circuit Breaker

500kV断路器的断口电容和介质损耗因素tanδ是反映设备运行状态的重要参数,需定期进行例行试验,但试验数据易受到现场条件影响。某次试验现场分合指定开关后,采用无屏蔽线的正接线测得的断口电容与介损值远超规定的限值范围,根据静电声源初步判定是相邻间隔的感应电压影响,并同时考虑油漆层电阻的影响。采用ATP-EMTP软件对这两种因素进行了仿真建模计算,结果表明,断口电容和介损值与感应电压呈线性关系,并随感应电压相位变化而上下振荡;正常情况下,油漆层和氧化层产生的接触电阻对电容值测量结果产生的影响很小,可忽略不计。本文所得研究成果对变电站现场电气设备试验具有一定的参考意义。

The break capacitance and dielectric loss factor tanδ of 500 kV circuit breaker are important parameters reflecting operation condition of the equipment. Routine tests shall be carried out periodically, but the test data is susceptible to on-site conditions. At a test site,after breaking the designated switch, the breakcapacitance and dielectric loss measured by the positive connection of the unshielded wire is well beyond the limit range which, according to preliminary judgment of electrostatic noise, is the inductive voltage influence of adjacent bay and, at the same time, the influence of paint layer resistance is also considered. Such two factors are simulated and modeled by the use of ATP-EMTP software. It is shown by the result that the capacitance and dielectric loss across open contacts shows linear relationship with inductive voltage and oscillates up and down with the variation of the inductive voltage. Under normally condition, the influence of the contact resistance generated by the paint layer and the oxidization layer is very less on the measurement result of capacitance and can be neglected. The study result in this paper has definite reference significance for the test of electrical equipment at substation site.