Abstract: A circuit breaker includes a tank grounded and filled with an insulating gas, a first electrical series-connected section having a main conductor and a main breaking section, and a second electrical series-connected section having a resistor and an advance closing contact device. The first electrical series-connected section is coupled electrically in parallel to the second electrical series-connected section. The fixed contact side of the main breaking section is supported by an insulating cylinder and the fixed contact side of the advance closing contact device is supported by an insulating plate from the fixed contact side of the main breaking section. A breaking unit, chiefly composed of the main breaking section and the advance closing contact device, is supported by insulating cylinders. A resistor unit is supported by an insulating cylinder.

Abstract: A gas-insulated switchgear in which a washer 5 is electrically connected with a tank 1 by a conductive material 12 having a high resistivity at a position where the tank 1 and a tank 2 are joined through an insulator 13 of the gas-insulated switchgear. In view of the structure of the switchgear, the reliability is improved, the structure is simplified, the number of parts is decreased, and the profitability is improved because a steep surge is not theoretically induced for a steep surge induced when turning on/off each unit at an electrically insulated position of a joint between tanks through an insulator of a gas-insulated switchgear for an SF.sub.6 gas-insulated closed-type station.