A novel design for a multistage corona stabilised closing switch

The possibility of controlling the voltage distribution across the gaps of a closing switch based on a cascade of corona stabilised electrodes has been examined. When operating in a corona stabilised mode the corona current flowing in each gap must be equal. By altering the corona characteristics of the gaps, through changing electrode separation and the area of corona emission, it should therefore be possible to control the voltage distribution across the elements of the cascade. A simple theoretical model of the behaviour of corona emission for an electrode with a protruding cylindrical corona generation element has been developed. Experimental tests have confirmed the broad validity of the model. The experimental data for individual electrode geometries has been used to predict the expected self break behaviour of a two gap cascade and the predictions are compared with experimental data. The voltage distribution across the cascade has also been measured and compared with the values predicted from the model.