Interrupting Characteristics of Puffer and Suction Type SF6 Gas Interrupter Especially in Thermal Breakdown Region

Abstract

Interrupting characteristics in thermal region within the range of 30-60kA current levels have been examined with an experimental model breaker under some SF6 gas pressures of 4.5-15 bars. The interrupter tested with the breaker was designed to shorten the arcing time based on the puffer principle with the aid of a suction chamber. Arcing time was shortened with the fastly established gas-flow into the suction chamber in comparison with conventional puffer type interrupters. Interrupting characteristics in short arcing time region were much influenced by interrupter structures, interrupting currents, filling gas pressures and rates of rise of recovery voltage (rrrV). Particularly, in large current region over 50kA, the minimum arcing time was sensitively affected by moving side interrupter structures. Using a newly developed interrupter characterized by a follower type insulating nozzle, it has demonstrated a minimum arcing time of 0.37 cycles for the 63kA 90% short line fault (SLF) condition for two breaks per pole under an SF6 gas pressure of 10 bars, and also has demonstrated 0.33 cycles for the 50kA 90% SLF condition under a pressure of 6 bars.