Investigation of an SF6 ultra high voltage circuit breaker using an opening resistor and auxiliary interrupter

Stresses of an interrupter during current interruption with a resistor in a UHV power system were calculated with a simple method. Interrupting abilities of some interrupters were compared by interrupting tests. A small puffer type interrupter showed the most suitable characteristics for the resistor interrupter. To realize a time interval of 28 ms from the opening of the main interrupter to the opening of the resistor interrupter, a delayed operating mechanism was constructed with independently movable parts. The operating characteristics of the mechanism were measured, and the required delay time was achieved