Pneumatic mechanisms for circuit breakers

ANEW AND MORE powerful unit has been added to a line of pneumatic operating mechanisms for power circuit breakers to meet the requirements of a 330-kv 25,000-mva breaker.¹ Three of the largest available mechanisms,² each operating a single pole, would have supplied the necessary power but required the solution of problems of synchronization and interlocking. Consequently, a new mechanism which can operate all three poles in the conventional manner was developed. It has many of the features proved to be effective and desirable in the rest of the line and can operate breakers requiring a closing effort of 160,000 inch-pounds.