Hitachi, Ltd.

Takehiro Kikuchi

Hiroshi Suzuyama

Jun Ozawa

Seizo Nakano

Minoru Sakaguchi

Kazuaki Oishi

Naoki Amano

Kyuji Yaginuma

Hitoshi Kayaba

Yoshirou Suzuki

Shigeru Fujiya

Syoetu Suda

Tosio Isikawa

An instrument current transformer for a main power cable which is composed of three power cables for three phases disposed in a power cable laying hole and three current transformer coils for the three phases, each of the three current transformer coils surrounding a corresponding one of the three power cables, the instrument current transformer including: a plurality of upper circumferential installation unit members disposed near an end portion of the power cable laying hole along circumference sides of an opening portion of the power cable laying hole, each of the upper circumferential installation members being provided with at least one securing portion extending in a radial direction and the upper circumferential installation unit members being secured to the end portion of the power cable laying hole via respective at least one securing portions; three axial installation members for the three phases, each extending along corresponding ones of the three power cables, first ends of the axial installation members being connected to the upper circumferential installation unit members and the three current transformer coils for the three phases being supported by corresponding ones of the three axial installation members; and a plurality of lower circumferential installation unit members having substantially a same configuration as corresponding ones of the upper circumferential installation unit members, the lower circumferential installation unit members being connected to second ends of the axial installation members opposite from the first ends.

Instrument current transformer for power cables

In a gas insulated switchgear equipment device, at least one gas insulated main bus bar is arranged on an attachment surface and a plurality of feeder units each having one end connected to the gas insulated main bus bar and the other end connected to an insulating terminal are arranged along a longitudinal direction of the gas insulated main bus bar, thereby constituting a substation equipment device. A gas insulated bus-section-unit is arranged on a portion of the gas insulated main bus bar and has at least a circuit breaker and disconnecting switches connected to both ends of the circuit breaker, and one end of the bus-section-unit is connected to the corresponding gas insulated main bus bar and the other end of the bus-section-unit is provided with at least one external lead-out device connectable to an external connecting device. With this arrangement, by the use of the bus-section-unit arranged on the portion of the gas insulated main bus bar, the substation equipment separated or increased can be easily interconnected or renewed.

Gas insulated switchgear with bus-section-unit circuit breaker and

A gas-insulated switchgear apparatus is disclosed, in which a bus bar-dividing unit is interposed through main bus bars between feeder units connected to a transmission line or a transformer. The main bus bars are arranged in substantially the same axis. A circuit breaker of vertical type making up the bus bar-dividing unit includes an upper electric path and a lower electric path. The lower electric path is connected to one of the main bus bars while the upper electric path is connected to the other main bus bar at a position displaced axially of the main bus bar opposed to the circuit breaker of vertical type. This construction with the circuit breakers of vertical type arranged on the same axis facilitates maintenance and inspection.

Gas-insulated switchgear apparatus

A gas insulated switch-gear wherein power circuit breakers, disconnecting switches, earthing switches and the like constituting a power electric sub-station are enclosed in earthed metallic vessels and insulation therein is effected by means of insulated arc-suppressing gas is housed in a switching house, a bushing forming a terminal at the electric power line side is provided separately outside of the switching house, and said bushing located outside and gas insulated switch-gear is electrically connected by means of gas insulated bus bar, to thereby eliminate a wall bushing.

Gas insulated switch-gear apparatus

Spark gap apparatuses are provided at the receiving end or the sending end of an electric power substation, in order to protect electric apparatus in the electric power substation against the surge voltage incoming from the power transmission lines. In the case where the gap of such a spark gas apparatus is placed in electronegative gas, for example SF.sub.6 gas, the spark voltage vs. spark time characteristic varies depending on the polarity of the surge voltage and thus the protecting performance of the spark gap apparatus is poor. The improvement in the protecting performance of the spark gap apparatus is provided by substantially equilizing the maximum electric field developed between the end surfaces of a pair of electrodes which are oppositely disposed to each other to form a spark gap therebetween.

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Hitachi, Japan

Takehiro Kikuchi