Experimental Approach to One-Cycle Puffer Type SF6 Gas Circuit Breaker

An experimental model of one-cycle circuit breaker based on the puffer principle has been developed. This experimental model was designed for 242/245kV 4OkA rating for one break per pole, to meet the ANSI and IEC Standard specifications. Through laboratory tests, it demonstrated minimum and maximum interrupting times of 0.5 and 1.3 cycles for both the 90o short line fault (SLF) and 100o breaker terminal fault (BTF) conditions, including symmetrical and asymmetrical current wave shapes. The experimental one-cycle breaker is furnished with a new type of puffer interrupter which is designed to work under high SF6 gas pressure and has a suction chamber as well as the conventional compression chamber, and provided with a newly developed oil hydraulic operating mechanism with a pilot valve driven by a force motor.