Abstract: In a gas insulated electric apparatus having gas sections filled with insulating gas, a locating device determines a position of a gas section in which an insulation abnormality is detected, on the basis of a detection signal from sensors disposed in each of predetermined gas sections. At the same time a hindering degree diagnosing device diagnoses the degree and the kind of the insulation abnormality, by comparing a detection signal from the sensors with data stored in a data base. A valve control generates a valve control signal, responding to the locating device and the hindering degree diagnosing device, and in response to the valve control signal, a trip circuit generates a valve opening signal to open an electromagnetic valve disposed in a gas section in which an insulation abnormality is detected.

Abstract: A gas insulated switchgear has a container which is filled with an insulating gas, a conductor disposed with the container, an insulator for supporting the conductor. An outer periphery of the insulator is made smooth so as to improve a dielectric strength of the device. The insulator is made of an organic substance base and an inorganic material filler added to the base. In order to improve the dielectric strength, the filler is atomised or the insulator is coated.

Abstract: A power apparatus has a network formed by a plurality of interconnected components being, e.g., one or more high voltage conductors in a casing of a metal filled with an insulating gas. Detectors are provided which detect electromagnetic waves, which are generated if there is a fault. The electromagnetic waves are analyzed to detect the location of the fault. The analysis may make use of attenuation coefficients corresponding to each component of the network to extrapolate between detectors on either side of the fault and/or to compare with predetermined wave strengths. A map of the network may be stored in a suitable memory to assist in the calculation of the fault location, and the memory may also store the attenuation coefficients themselves. The location of the fault may then be displayed by a suitable display, to give the time variation of the fault.