Development of Dielectric Loss Test Device for Aged Insulating Spacer Taken from Long-term Service GIS

In order to solve the current situation that there is no device for high voltage dielectric loss test in the field which is applied to full-size GIS insulating spacer in aging test or substation GIS service. So we develop the full-size insulator test box that can reduce the electromagnetic interference of the insulating spacer and fix the stray capacitance. Compared with the Schering Bridge, the advantage of the current comparator bridge is analyzed, and the stray capacitance around the measured insulating spacer is calculated equivalently, and its influence on the test circuit is also analyzed. The shielding performance of full-size insulator test box is carried out by experimental verification. By measuring the dielectric loss standard device, the measurement error of the test system is calculated. The contrastive test results between the new and five-year long service insulating spacer are studied. The results show that: the current comparator bridge has higher accuracy and can work at voltages of 20kV or higher. The dielectric loss measurement error of this test system is within 2%, which can ensure the effectiveness of the test results. At the voltage of 20kV, the new insulating spacers shows good electrical insulation properties, and the test results of capacitance and dielectric loss have hardly changed. But the test results of five-year long service insulating spacer have changed greatly, especially the change of dielectric loss value is very obvious. Therefore, the test system can monitor the working status of the insulating spacer at different aging times and evaluate the aging status through its values of capacitance and dielectric loss. It is a great significance to the safe operation of the GIS, because of the timely discovery of the insulators that need to be decommissioned.