Electrode erosion and lifetime performance of a triggered, corona-stabilized switch in SF6, at a repetition rate of 1kHz

This paper describes the work undertaken to investigate the electrode erosion and lifetime performance of an electrically triggered, corona stabilized (TCS) switch. The switch, which had a rod-plane geometry, was filled with SF6 at a pressure of 0.8 bar (1.0bar = 100kPa) absolute and was operated at a pulse repetition frequency (PRF) of 1kHz. The erosion rates of anode and cathode electrode materials such as elkonite (a copper tungsten composite), brass, aluminum and two types of stainless steel was measured, and their surfaces were studied optically, photographed and chemically analyzed. The erosion rate of the anode (rod) electrode materials ranged from 21.39 x 10-6 cm3C-1 for elkonite to 60.4 x 10-6 cm3C-1 for brass, whilst a cathode (trigger disc) erosion rate as high as 51.23 x 10-6 cm3C-1 for aluminum was measured. The lifetime of the TCS switch was experimentally determined for each of the electrode material tested, and was found to be inversely proportional to the erosion rate of the rod electrode. The electrode surface morphology and the gas-electrode compound distribution have also been evaluated to address the erosion mechanism in effect. Additionally, the influence of rod electrode surface conditions and gas deterioration has been investigated in respect to the performance and operational behavior of the TCS switch