电容式套管局部放电的末屏地线UHF传感

UHF Sensing of Partial Discharge in Condenser Type Bushing from End Shield Grounding Tap

电容式套管是重要的电力设备,局部放电测量对于保证其安全运行具有重要意义。文中提出了在套管末屏接地上进行局部放电UHF传感的方法,在末屏接地线上串联足够小的电感,不影响末屏接地的性能,但能够有效地在UHF频段传感套管的局部放电。对变压器套管油中尖端、变压器套管内部气泡和电流互感器内部气泡等缺陷进行了试验,结果表明,这些绝缘缺陷的局部放电信号具有UHF频率分量,采用末屏地线UHF传感器能够有效进行这些局部放电的UHF信号耦合。

Partial discharge（PD）detection of condenser type bushings is significant for accessing their insulation conditions. In this paper, a PD detection method for condenser type bushing is proposed. The PD is sensed in UHF way with a small inductance which is integrated inside the end shield grounding tap of the bushing and is connected in series in the grounding wire. The inductance is so small that having little influence on grounding performance, but sensitive enough to the UHF PD signals. Tests are performed with three insulation defeats including sharpness in the high voltage terminal of bushing in oil, air voids inside a transformer bushing and air voids inside a current transformer. The test results show that the partial discharges of the three insulation defeats can produce electric signals in UHF band and the inductance integrated inside the end shield grounding tap can pick up the UHF signals effectively.