Dielectric Loss Factor Measurement in A Gas-Insulated Transmission Line by Using Very Low Frequency Test

Abstract

Very low frequency tan delta measurement (VLF-TD measurement) is one of the insulation diagnosis methods usually uses to diagnosis the condition of electrical cable insulation. However, this research focuses on using VLF-TD measurement with a gas-insulated transmission line (GIL). The 230kV, 2500A, single phase, GIL with 2.0 m length was installed and prepared for experiments. in this paper, VLF-TD experiments were divided into 5 cases, classified by using types of artificial defects as a criterion, i.e. 1) The clean GIL without any defect, 2) The GIL with scratched on the surface of cone insulator, 3) The GIL with tracking path on the surface of cone insulator, 4) The GIL with protrusion on high voltage conductor and 5) The GIL with protrusion on enclosure. The average tan delta, VLF tan delta stability, and VLF differential tan delta were presented and compared in this paper.