Abstract: A switchgear has an insulating container filled with an insulating gas, a fixed current-carrying shaft fixed airtightly to one opening of the insulating container, a fixed contact provided on an end of the fixed current-carrying shaft in the insulating container, a movable contact configured to separably contact the fixed contact, a movable current-carrying shaft having the movable contact provided on an end and airtightly movably penetrating the other opening of the insulating container, and an operation mechanism coupled with the movable current-carrying shaft at an outside of the insulating container. The insulating container is constituted by a plurality of insulating layers, and the insulating layers are higher in dielectric constant as closer to an inside of the insulating container.

Abstract: A third electrode (8A) is soldered, via a support fitting (9) onto the inner surface of a support part (1a) which projects into the intermediate part of the inner surface of an insulation tube (1A). An arc generated between the fixed-side contact (5A) and the movable-side contact (5B) when the switch is opened is led from the outer periphery of the fixed-side contact (5A) via the third electrode (8A) to the movable-side contact (5B), in a so-called two-point switch, and the dielectric breakdown probability is thus reduced, particularly at low voltages. The third electrode may have its outer periphery exposed from the insulation tube and be used as one electrode when conditioning is carried out. By the use of this structure, the present invention is capable of meeting the demands for environmental protection and insulation reliability.

Abstract: A third electrode (8A) is soldered, via a support fitting (9) onto the inner surface of a support part (1a) which projects into the intermediate part of the inner surface of an insulation tube (1A). An arc generated between the fixed-side contact (5A) and the movable-side contact (5B) when the switch is opened is led from the outer periphery of the fixed-side contact (5A) via the third electrode (8A) to the movable-side contact (5B), in a so-called two-point switch, and the dielectric breakdown probability is thus reduced, particularly at low voltages.

Abstract: In this vacuum interrupter device, one or more upper terminals and lower terminals connected to a vacuum interrupter built in the device are attached to an insulating barrier which is provided with a plurality of chambers opening outward and capable of being closed by removable covers. In each of said chambers is placed one of non-linear resistors as many as said upper or lower terminals, one end of each of said resistors being connected to one of the upper or lower terminals corresponding thereto which is connected to the electric load, thereto and another end of each of said resistors being grounded through a switch.