Abstract: An apparatus for detecting position of internal fault in a gas-insulated bus bar (1) comprises electrodes (30) each of which are provided in section of predetermined length along axial direction of the tubular-shaped housing and the electrodes (30) can detect changes of voltage of a conductor (3) in each section and thereby can detect a point of fault.

Abstract: An arc detector includes a luminous diode 22 for irradiating the space within a vessel 1 containing an electrical device such as a bus bar 5 and filled with insulating gas such as SF.sub.6. A shielded photo-diode 24 receives light reflected back from a fine powder 12 produced when an arc occurs, and drives an indicator 8.

Abstract: A self-extinguishing circuit interrupter wherein a pair of separable contacts is disposed within an arc extinguishing gas. Energy of an electric arc established between the separated contacts is utilized to increase the pressure of the arc extinguishing gas, and the high pressure gas thus generated is introduced into a pressure chamber to be stored therein. When the arc current approaches zero, the high pressure gas within the pressure chamber is puffed to the arc to extinguish it. A plurality of pressure chambers are axially disposed, i.e., in the direction in which the movable contact moves, thereby improving the arc extinguishing capability of the circuit interrupter.

Abstract: A circuit interrupter comprises a pair of contacts in a container filled with a gas for extinction; an insulation nozzle around the contacts to form an arc chamber; a gas chamber which is connected to the arc chamber under departing the contacts. The gas pressure in the arc chamber and the gas chamber is increased by the energy of the arc generated at the departing the contacts. When the arc current is large, the flow-out of the gas from the arc chamber and the gas chamber is decreased by the arc whereas the high pressure gas in the arc chamber and the gas chamber is discharged through the insulation nozzle into the container at the time decreasing the arc current near zero whereby the arc is interrupted by the gas flow discharged.

Abstract: In a gas interrupter, high pressure gas such as air and SF.sub.6 is puffed to an arc so as to perform the extinction of the arc and a part of the passage of the arc is limited to narrow space and the arc voltage is raised at the narrow part and the other part of the passage of the arc is kept in wide space and the puffing rate of the high pressure gas is kept high enough at the wide space.