Research on Insulation Defect Detection Effectiveness of On-site Impulse Voltage Test for GIS Equipment

摘要

Increased operating voltages and more extensive power grids have given rise to increased gas-insulated metal-enclosed switchgear (GIS) failure rates. Kinds of insulation defects in GIS may occur in the process of transportation and installation; they cause insulation accidents. On-site lightning impulse (LI) test, which is particularly sensitive to abnormal field configurations, is, therefore, essential before GIS equipment is put into operation. The on-site LI waveform, restricted by the large load capacitance and impulse generator inherent inductance, has a long wavefront time T_f compared with standard LI, called non-standard LI. The non-standard LI test has been carried out in the field. But its insulation defect detecting effectiveness is not clear. In order to evaluate the effectiveness of the non-standard LI test in detecting defects in GIS, we investigated the breakdown characteristics of SF6 in a highly inhomogeneous electric field.