Tokyo Shibaura Denki Kabushiki Kaisha

Kabushiki Kaisha Toshiba

Susumu Nishiwaki

Satoru Yanabu

Toshikazu Satoh

Masayuki Ishikawa

Hironori Suzuki

Minoru Saito

Nobuyuki Takahashi

Katsumi Suzuki

Yoshiyasu Itoh

Yoshimasa Sato

Hisatoshi Ikeda

Hideyasu Ando

Eiichi Haginomori

Hitoshi Mizoguchi

Toshiya Imai

Hideyasu Andoh

Hiroshi Kusuyama

Masaru Okamoto

Koichi Futagami

Tsuneharu Teranishi

Yoichi Murakami

Mizuho Yamashita

Tsuyoshi Kokumai

Tsutomu Fujioka

Toru Tamagawa

Susumu Imai

Tadashi Koshiduka

Hirokuni Aoyagi

To suppress the magnetizing inrush current occurring when supplying power of three phases of the transformer are performed simultaneously using three single-phase circuit breakers or a non-phase segregated operation-type circuit breaker, without providing a circuit breaker with a resistor or other equipment. A magnetizing inrush current suppression method for transformer suppresses a magnetizing inrush current occurring at the start of energizing of a three-phase transformer, when a three-phase power supplyis input to a terminal of each phase by means of a three-phase circuit breaker. In the method, by integrating phase voltages or line-to-line voltages on the primary side or the secondary side or the tertiary side when three-phase AC voltages are applied in a steady state to the transformer, steady-state magnetic fluxfor each phase of the transformer is calculated, and the polarity and magnitude of the residual magnetic fluxof each phase of the transformer after the circuit breakershuts off the transformer are calculated, and the three-phase circuit breaker is caused to close simultaneously in a regionin which three phases overlap, each of the three phases having the polarity of the steady-state magnetic fluxequal to the polarity of the residual magnetic fluxfor each phase of the transformer.

Magnetizing inrush current suppression device and method for transformer

A non-linear resistor comprises a sintered body having zinc oxide as a main component, a side-surface high resistance layer arranged at a side-surface of the sintered body, and an electrode arranged at upper and lower surfaces of the sintered body. The side-surface high resistance layer is formed of a specifically selected material. The end-to-end distance between an end portion of the electrode and a nonlinear resistor end portion including the side-surface high resistance layer falls within a range of 0 mm to the thickness of the side-surface high resistance layer+0.01 mm.

Nonlinear resistor and method of manufacturing the same

A nonlinear resistor is formed by forming side surface insulating layer 2 on a sintered body 1 which contains zinc oxide as a main component and providing a pair of electrodes 3 on upper and lower surfaces of the sintered body 1. The electrodes 3 are formed by plasma thermal spraying of less than 10 kW in an atmosphere in which an oxygen concentration is set to 22 volume % or less. The electrodes 3 are formed of aluminum, copper, zinc, nickel, silver, or their alloy whose average particle size is within 5 .mu.m to 50 .mu.m. Preferably porosity is less than 15%, weight percentage of metal oxide is less than 25%, average film thickness is within 5 .mu.m to 500 .mu.m, average surface roughness is less than 8 .mu.m, and resistivity is less than 15 .mu..OMEGA..multidot.cm. Accordingly, the nonlinear resistor having the excellent discharge withstand can be provided.

Nonlinear resistor with electrodes formed by plasma spraying

A disconnector for a gas insulated switchgear in which the disconnector includes, in a metallic container filled with an insulated gas, a stationary electrode having a contact, a stationary electrode shield electrically connected to the stationary electrode to surround the contact, the stationary electrode shield made of an electrically resistant material and having a free end portion and inner and outer surfaces, and a movable electrode arranged to face the contact and being movable into and out of electrical contact with the contact, and in which the stationary electrode shield is arranged to flow discharging current therethrough due to an interelectrode voltage applied between the stationary electrode and the movable electrode. The disconnector includes an annular metallic electrode coaxially mounted on the free end portion of the stationary electrode shield so as to allow the movable electrode to pass therethrough. The metallic electrode has an exposed surface exposed to the insulated gas and the exposed surface of the metallic electrode is adapted to be larger in field strength than the inner and outer surfaces of the stationary electrode shield for producing the discharge between the exposed surface of the metallic electrode and the movable electrode.

Disconnector of gas insulated switchgear

A superconducting current limiting apparatus includes a first container, a superconducting current limiting element accommodated in the first container, a refrigerant filling the first container for cooling the superconducting current limiting element accommodated in the first container, a second container for accommodating the first container in such a manner that the first container is heat insulated, and a conductor for connecting the superconducting current limiting element to an external power supply system. Such a superconducting current limiting apparatus can be used to limit a short-circuit current. It can be incorporated in a short circuit controlling superconducting system.

Superconducting current limiting apparatus

A gas-insulated switching apparatus comprises gas-insulated interrupters, gas-insulated buses and gas-insulated disconnecting switches, whereby the movable electrode side terminals of all the disconnecting switches accommodated in the apparatus are so arranged as to be connected to gas-insulated interrupters to be disconnected from a power source, i.e., to a load line side to be interrupted by the disconnectors.

Gas-insulated switching apparatus

An arrester having at least two stacks of non-linear resistors connected in series, an arcing gap device connected to shunt one stack of resistors when the gap means sparks over, and a hermetically sealed housing enclosing the resistor stacks and arcing gap device and filled with sulfur hexafluoride gas having a gauge pressure not less than 2 kg/cm.sup.2. The impedance of the one resistor stack is from about 15% to about 35% of the total impedance of the two resistor stacks when the arcing gap means sparks over, and the rated voltage of the arrester is not less than about 50 KV.

Lightning arrester

A lightning arrestor comprising at least two stacks of resistor disks juxtaposed within a housing and electrically connected in parallel. The stacks include the same number of disks, at least 35, and preferably 100 or more. Each stack comprises at least two sub-stacks which are aligned end-to-end and electrically connected. Adjacent sub-stacks of parallel stacks are mechanically connected but electrically insulated from each other.

A series circuit of a gap section and a valve block is connected between a transmission line and the ground. The valve block consists of a plurality of nonlinear resistor elements connected in series. A first impedance circuit consisting of a resistor and a capacitor connected in series is connected in parallel to the gap section. Also, a second impedance circuit consisting of another resistor and another capacitor connected in parallel is connected in parallel to the valve block. The ratio of the voltage applied across the gap section to that applied across the valve block is determined by the ratio of the impedance of the first impedance circuit to that of the second impedance circuit. A pair of discharge electrodes included in the gap section, which are a prescribed distance apart from each other, comprise a narrower gap region at which spark is started.

A circuit breaker apparatus of high voltage direct currents is connected in series with an external circuit comprising an AC-DC converting device connected to an AC power supply and a DC reactor connected to the AC-DC converting device, and comprises a circuit breaker connected in series with the external circuit, a disconnecting switch connected to the circuit breaker, and a series circuit connected in parallel with the circuit breaker and constituted of a blocking capacitor and a primary winding in a transformer. A charge storage capacitor is connected to a secondary winding of the transformer through a starting switch and polarity changeover switch, and an AC power supply for charging is connected through a diode to the charge storage capacitor.

Circuit breaker apparatus for high voltage direct currents

An arrester comprises a plurality of blocks connected in parallel between first and second connecting metal plates and each comprised of a plurality of stacked nonlinear resistor elements, at least one block comprised of a plurality of stacked nonlinear resistor elements and connected between the second connecting metal plate and a third connecting metal plate grounded, and a discharge gap connected in parallel with the later-mentioned block and between the second and third connecting metal plates. The discharge gap is provided below one of the blocks connected in parallel between the first and second connecting metal plates.

Arrester

A direct current circuit interrupting apparatus of the type wherein the arc of the circuit interruptor is extinguished by passing an oscillatory current from an oscillating circuit to the interrupted contacts via a switch means which is closed at the time when the circuit interruptor is opened includes a nonlinear resistor comprising a sintered mixture of metal oxides connected in parallel with the oscillating circuit.

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Yokohama, Japan

Susumu Nishiwaki