Designing the vacuum interrupter for applications at 72.5 kV and above

This paper reviews the design and manufacturing aspects of the high voltage (HV) vacuum interrupters (VI) for the emerging global markets in the voltage ratings at 72.5 kV and above. Some of the key design issues and challenges are identified and discussed for a possible solution. Results of the study of different design aspects, different components processing routes, high vacuum seal-off and post seal-off processing techniques have been presented which help in understanding to improve the quality, performance and the environmental signature of the HV VIs. Based on the study of existing literature and ideas derived from other technologies, novel approaches to design and manufacture VIs have been outlined for possible study and development. For improved VI layout designs, selection of new materials and components such as bellows, ceramic housing, contacts, OFHC copper conductor, getter and other structural materials have been examined. Similarly, processes such as electropolishing, components cleaning and increasing the process seal-off temperature have been looked at. For improving the voltage performance, effect of loose particles due to processes and arcing contacts and processes such as in-process cleaning, HV conditioning have been discussed.