Patent ID: 7339132

Claim:
A method of interrupting current of a puffer type gas circuit breaker having at least a pair of arc contacts connected to an operator, the method comprising: by means of the operator, compressing arc quenching gas in a compression chamber formed by a cylinder and piston upon a separation movement of the arc contacts, one of which is slidably connected to the cylinder and piston and blasting the compressed gas guided through an insulating nozzle towards an arc generated between the arc contacts thereby interrupting the current, said method furthercomprising, before blasting the arc quenching gas, a holding step for moving the position of the compression chamber towards the interruption direction, while keeping the volume of the compression chamber substantially the same as when the gas circuit breaker is in an initial switched on state, and then a compressing step for compressing the arc quenching gas at a final stage of the interruption operation, followed by blasting the arc quenching gas, while reducing the volume of the compression chamber.