Compressed-air circuit breakers in A-C railway service

The increasing interest in compressed air as an interrupting and operating medium for circuit breakers in central-station and industrial service, together with its gratifying record in service periods extending up to five years, warrants investigation of its application to a-c railway service. Previous developments leading up to present standards of requirement for this service are reviewed, and a description is given of a compressed-air breaker designed for highspeed interruption of short circuits on contact line feeders in single-phase 25-cycle railway service at 12,000 volts to ground. Application of the principle to other railway service is discussed.