A new milestone in circuit-breaker interrupting capacity 25 million kva at 330 kv

With the tremendous loads considered for 330-kv lines, circuit breakers functioning at this voltage are needed with 2,000 amperes continuous current capacity and an interrupting rating of 25 million kva. The description of a breaker's new design, permitting the full interrupting rating to be demonstrated with present test facilities, and its assembly demonstrate how designers and engineers have solved the problems presented by the power companies. FIVE YEARS ago development progress was reported on circuit breakers rated 10 million kva at 230 kv.^1,2 Since that time breakers of this rating have been built and installed on 138-kv, 161-kv, and 230-kv systems.^3–5 Instead of this rating proving to be a ceiling, an interrupting capacity of 15 million kva has been considered at 161 kv, 230 kv, and 330 kv. Now the heavy loads being projected for 330-kv lines in this country, particularly the tremendous concentration of electric power at the new Atomic Energy Commission plant near Portsmouth, Ohio, have brought a demand for 330-kv breakers with 2,000 amperes continuous current capacity and the unprecedented interrupting rating of 25 million kva. This article describes one way in which this challenge has been met, and in particular how the high arc-rupturing capacity has made necessary a radically new design which will permit the full interrupting rating to be demonstrated adequately with available High Power Laboratory testing facilities.