Comparative Testing of Simple Terminations of High-Voltage Cables

Comparative testing of simple terminations of high-voltage cables has been reported. Cable terminations are one of the weakest links. The majority of failures occur on the ground shield side. Several termination types for polyethylene HV cables were tested for dielectric strength and LC, down to the picoampere level. High-voltage leads of all cables were connected physically to the HV electrode of a voltage divider capable of corona suppression up to 130 kV. The cable-insulating system comprising PE, SHT, and air is difficult to analyze because of its ill-defined geometry and the nonlinear electrical characteristics of some of the materials. Stress-grading tapes reduce (and greatly stabilize) leakage currents, at a level around 1 nA at 100 kV and room temperature. They also increase the breakdown voltage to approximately 130 kV for a 15-cm length of insulation.