Abstract: A failure determining apparatus for a gas-insulated electrical appliance where the appliance is a cylindrical metal container with a charged conductor, insulating gas, and a plurality of insulating spaces inside for supporting the conductor and partitioning the container. The failure determining apparatus has a high-speed developing sensor which detects a high-speed phenomenon caused by a failure within the gas sections; a first failure determining circuit which determines the presence of a failure from an output of the high-speed developing sensor; a low-speed developing sensor which detects a low-speed phenomenon caused by a failure within the gas sections; a second failure determining circuit which determines the presence of a failure from an output of the low-speed developing sensor; and an arithmetic control circuit which identifies a gas section of the metal container in which a failure occurs from an output of the first and second failure determining circuits.

Abstract: A failure determining apparatus of a gas-insulated electrical appliance determining a failure, having a cylindrical metal container, a charged conductor housed in the metal container filled with an insulating gas, and a plurality of insulating spaces insulation-supporting the charged conductor from the metal container and partitioning the interior of the metal container into gas sections, comprising a high-speed developing sensor which detects a high-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a first failure determining circuit which determines the presence of a failure from an output of the high-speed developing sensor; a low-speed developing sensor which detects a low-speed phenomenon caused by a failure such as a ground-fault or a short-circuit within the gas sections; a second failure determining circuit which determines the presence of a failure from an output of the low-speed developing sensor; and an arithmetic control circuit which identifie

Abstract: A circuit breaker for opening and closing contacts disposed on each phase of a multiphase electric power line has a photo-diode array and a light emitting diode array disposed on opposite sides of a driving rod of a driving mechanism, with a light passing aperture provided in the driving rod. When the aperture in the rod crosses the respective light paths between the photo-diodes and the corresponding light emitting diodes, the photo-diodes issue electric output signals corresponding to movement of the driving rod. By processing these output signals, any abnormal breaking of the breaker contacts among the phases is detected.