并联电容对正接法测量高压电气设备介质损耗值的影响分析

Influence of Shunt Capacitor on the Dielectric Loss Factor of HV Equipment Measured by Positive Connection Method

介质损耗试验时,传统做法和理论分析均采用正接法,因为正接法对并联在被试设备两端的电容有良好的屏蔽作用。但试验发现并联电容易造成介损值偏大。通过试验和理论分析发现,由于套管氧化层电阻的影响。如果在回路中串联了接触电阻,则并联在被试设备两端的电容就会对整个测量系统造成影响,且电容量在回路中占总电容量的比例越大,对介损值的影响也就越大。

Positive connection method for dielectric loss test used in conventional practice and theoretical analysis can have good shielding effect on the capacitor shunted at two ends of tested equipment.The dielectric loss factor is found too large due to the parallel capacitor and the influence of oxide resistance in the casing pipe.Test and theoretical analysis indicate that if test circuit is in series with contact resistance,the capacitor shunted at two ends of the equipment can affect the whole capacitance measuring system and the larger is the proportion of capacity in the circuit,the bigger the effect on the dielectric loss factor is.