Design and implementation of an SF/sub 6/ interrupting chamber applied to low range generator circuit breakers suitable for interruption of current having a non-zero passage

New types of SF/sub 6/ interrupting chambers, which implement innovative interrupting principles, have been developed during the past years, based on the objectives of reducing the operating energy of the circuit breakers and consequently increasing their reliability. This paper describes the rear-exhaust-type "self blast" double-volume thermal chamber, which was designed with the help of new chamber development software programs, of the physical imaging model of the arc. Simulations and confirmation by laboratories tests the interruption of short-circuit currents and, especially, the testing of short-circuit currents that have a nonpassage by zero on such a new chamber for applications to generator circuit breakers are shown and evaluated.

I. Introduction

Generator circuit breakers, located between the generator and the stepup transformer, have proven to be an economical and efficient solution for the protection of generators and transformers. They are widely used today for generator ratings ranging from 100 to 1300 MVA. SF6 circuit breakers are generally applied when interrupting capabilities of 63 to 120 kA are specified, while air-blast generator circuit breakers are dominant when a higher interrupting capability is required.