CHARGE ACCUMULATION ON INSULATING SPACERS FOR HVDC GIS

A technique to design, fabricate and test dc gas-insulated switch-gear has been developed to apply the advantages of compressed gas insulation to metal-enclosed HVDC equipment. Charge accumulation on solid insulators is one of the fundamental problems which have to be solved in establishing the design stress for HVDC equipment. The present paper is a review of the studies which have been performed in the development of a +/- 125 kV HVDC gas-insulated converter station and +/- 500 kV HVDC-GIS. The properties and mechanisms of surface charging, the optimum design of the spacer and its breakdown characteristics are summarized. Problems associated with capacitive probe measurement of surface charge and a practical solution to obtain the charge distribution on the spacer, are presented.