High-Voltage Oil Circuit Breakers for 5,000,000- to 10,100,000-Kva Interrupting Capacity

The paper describes some of the special design features for steel-tank oil circuit breakers rated 5,000,000 kva at 138 kv, 161 kv, and 230 kv, and rated 7,500,000 or 10,000,000 kva at 230 kv. The method of verifying these interrupting capacities both in the manufacturers´ high-power laboratory and by field tests on a customer´s property is outlined, with special consideration given to the problems of switching line-charging currents and of interrupting high power repeatedly, under both standard duty and rapid reclosing duty cycles.