Improved Outdoor Oil Circuit Breakers for Medium Voltages [includes discussion]

A new line of improved outdoor oil circuit breakers for 14.4-, 23-, and 34.5-kv service, integrating many years of operating experience into designs stressing reduced maintenance, is now available. Cognizance of the rising costs of power-system maintenance has resulted in the development of a circuit-breaker line not only designed to incorporate performance improvements but also designed to provide low maintenance costs. This paper outlines the objectives established to guide the design program and describes the improved line of oil circuit breakers. Low oil carbonization and decreased contact erosion have been effected by the reduced arcing times of the new interrupters. Inspection and adjustment time have been minimized on interrupter and mechanism assemblies. Accessibility has been increased by simplification of the circuit-breaker framework and linkages. Improved insulation features are provided in bushings and in current transformers. The performance of all ratings has been proved by an extensive test program.