The Vertical-Flow Interrupter and Its Application to ``Oil-Poor´´ Circuit Breakers

The historical background of the development of the vertical-flow interrupter for ``oil-poor´´ circuit breakers is reviewed. A description of the interrupter and its theory of operation is given. The application of two of these interrupters to a 138-kv 1¿-million-kva ``oil-poor´´ porcelain-clad circuit breaker is shown, together with laboratory test results. A review is given of important field tests on a 138-kv single-pole unit, tested line to ground on a large 220-kv operating system up to approximately 2¿ million three-phase kva. Magnetic and cathode-ray oscillograms of these tests are shown.