A 2,500,000-kva compressed-air powerhouse breaker

THE use of compressed-air breakers for indoor service has become established by several field installations since the presentation of papers1,2 describing these devices two years ago. At that time complete tests had been made justifying ratings to 1,500,000 kva. Since then, powerhouse requirements have demanded the development of similar breakers for 2,500,000 kva. During the same interval new laboratory facilities have been provided3 which are capable of completely testing these large breakers. This paper describes the theory and construction of this new breaker and for the first time presents test results of full 2,500,000 kva under three-phase fault conditions, together with a study of associated voltage recovery rates.