Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Haruhiko Kohyama

Hiroki Ito

Daisuke Yoshida

Yuji Yoshitomo

Kenji Kamei

Takashi Hirai

Hiroyuki Tsutada

Mikio Hidaka

Hiroyuki Sasao

Katsuhiko Horinouchi

Sadayuki Kinoshita

Suenobu Hamano

Yoshiki Hirano

Masaki Hiratsuka

A residual magnetic flux measurement apparatus measures residual magnetic fluxes by using a transformer-voltage measurement means for measuring transformer voltages; a voltage delay means for delaying the measured signals; a DC-voltage-component calculation means for calculating DC voltage components from the latest transformer-voltage signals for a predetermined time period based on calculation-control signals; a voltage integration means for calculating voltage-integration signals by performing voltage integration of signals obtained after separating the DC voltage components from present transformer-voltage signals; a magnetic-flux DC-component calculation means for calculating magnetic-flux DC-components from the latest voltage-integration signals for a predetermined time period based on the calculation-control signals; a magnetic flux calculation means for obtaining magnetic flux signals in which the magnetic-flux DC-components are separated from present voltage-integration signals; and a control means for obtaining residual magnetic fluxes based on contact signals, an interruption mode, the transformer-voltage signals, and the magnetic flux signals.

Residual magnetic flux determining apparatus

A gas circuit breaker includes a grounded tank corresponding to each one of the plurality of phases, a bushing, an upper housing, and a lower housing, those mounted on a base that is supported by a frame. The grounded tank and the upper housing are located on a plane. The lower housing is connected to the grounded tank with a connecting unit such that the lower housing can be moved from a first position for operation lower than the plane to a second position for transportation substantially on the plane.

Gas circuit breaker

A gas-circuit breaker includes a cylinder, a stationary piston, and a moving piston. The cylinder has a moving contact that is fixed on one end of a rod and has a gas exhaust that faces a stationary contact. The rod is inserted into the cylinder. The stationary piston is fixed to the container, and is fitted in an opening of the cylinder to create a puffer chamber. Due to movement of the rod, the stationary piston compresses arc-extinguishing gas, and the gas blows onto the arc through gas exhaust. The moving piston partitions the puffer chamber into a first puffer chamber and a second puffer chamber. Sliding of the moving piston changes the capacity of the first puffer chamber and the second puffer chamber according to the difference in pressure in the first puffer chamber and the second puffer chamber.

Gas-circuit breaker

A target-closing phase-map generating section generates in advance a target closing phase map in consideration of a pre-arc characteristic and variations of a mechanical action of a breaker, and amplitude fluctuations of the load voltage. A target-closing time calculating section calculates a target closing time string from frequencies and phases of the power source voltage and the load voltage, respectively, of the breaker referring to the target closing phase map. A closing control section, when a close commandis inputted, controls the timing of outputting a closing control signal based on a predicted closing time and the target closing time string.

Controlled switching device

A puffer-type gas blast circuit breaker is capable of restraining reduction in creepage insulation resistance of an insulating support and an insulating rod due to insulating gas of high temperature. An electrode section is mounted on a stationary member supported on an insulating support, and a stationary side arc contact and moving side arc contact are disposed facing each other to contact and separate; a hollow piston rod and an insulating rod are connected to the moving side arc contact, and inserted in a stationary member body portion; and a gas flow blocking member is mounted on an end of the piston rod to prevent an insulating gas heated and coming to the stationary side from getting into the insulating rod side. The stationary member body portion is formed cylindrical so that a gap between the body portion of the stationary member and the gas flow blocking member is minimized.

Puffer-type gas blast circuit breaker

The gas insulated switchgear includes a rotary shaft which penetrates a pressure vessel is connected with a moving part which is housed in the pressure vessel by way of a lever, and is connected to the moving part, and brackets which support the rotary shaft and are mounted on a mounting portion which is formed on the pressure vessel. The brackets are fixed to the mounting portion formed on the pressure vessel using a plurality of fixing bolts which are arranged in a spaced-apart manner on an eccentric circle having the center at a point xoffset from the center of rotation xof a rotary shaft and hence, the brackets can be fixed to the mounting portion formed on the pressure vessel at a predetermined angular position which uses the point xoffset from the center of rotation xof the rotary shaft as the center of rotation.

Gas insulated switchgear

Respective contact terminals in respective arc-suppressing spaces of respective breakers are opened at a voltage zero point of any phase of three phases, simultaneously among the three phases. If current breaking is carried out for the three phases at the same time, when the breakers of the three phases are opened, the residual magnetic levels of the respective phases of a transformer can be controlled so that the residual magnetic flux level of the phase opened at the voltage zero point is maximum (for example, &#x2212;2K or +2K) and the residual magnetic flux level of the other two phases are opposite in polarity to the residual magnetic flux level of the phase concerned and equal to substantially the same residual magnetic flux (for example, +K and +K or &#x2212;K and &#x2212;K) which is equal to about one half of the residual magnetic flux level of the phase concerned. Accordingly, by throwing the phase broken at the voltage zero point at a first time, the difference in residual magnetic flux between the second throwing phase and the third throwing phase just after the first phase is thrown can be substantially nullified.

Phase control switching device

A closing phase that produces the smallest energization flux error at a connection input point is calculated based upon a residual flux of the first closing phase and the preliminarily given pre-arc characteristic and closing time deviation characteristic of a three-phase circuit breaker, so that the calculated phase value is set as a target closing phase of the first closing phase. A closing phase that produces the smallest energization flux error when a residual flux of zero is calculated, so that the calculated phase value is set as a target closing phase of the remaining two phases. The total time required from the reference point to the target closing phases of the remaining two phases and a delay time corresponding to an integer multiple of a given cycle of the three-phase power supply is set as a target closing time of the remaining two phases.

Transformer inrush current elimination system

A phase control switch apparatus incorporating a phase-based break/make controller ( A, B, C) for protecting a reactive load such as a transformer ( ) from transient surge phenomena taking place upon power-supply breaking/making operation. The phase control switch apparatus includes a reference phase detecting unit ( ) for predicting phases of the phase-voltage and phases-current waveforms upon closing and opening of the breaker contacts, a residual magnetic flux detecting unit ( ) for predicting residual fluxes in each phase of the transformer ( ) on the basis of time points at which the breaker contacts of the individual phases were opened in the preceding breaking operation and polarities of the phase-currents immediately before the breakage, an operation control unit ( ) for predicting optimal closing time points for the individual phases at which the transient surge can be suppressed to a minimum on the basis of the predicted residual fluxes

Phase control switch apparatus

A synchronous switching apparatus for detecting a source voltage of each phase to close each phase at an electrical phase angle predetermined for each phase, including switching devices provided one for each phase for opening and closing an impedance load, switching devices for closing and opening the switching devices for each phase, measuring transformers for measuring source voltages of the respective phases and phase-to-phase voltages, and phase control devices each for issuing a command for energizing the impedance load at an electrical phase angle in a range predetermined for each phase, when detecting a zero point of a source voltage of each phase or a zero point of each phase-to-phase voltage.

Synchronous switching apparatus for use with a multiple phase power system

A phase control switching system for controlling opening and closing timings of a power switching device to suppress the occurrence of an exciting rush current or a make-and-break surge voltage which is severe to system equipment such as a transformer, a reactor and a capacitor bank, or for controlling an arcing time of a circuit breaker to put the circuit breaker into operation for the arcing time leading to no-re-ignition or for the optimal breaking time. In the phase control switching system, a current measuring section or a current gradient measuring section is provided to measure a current value or a current gradient value of a current to be broken or introduced, and a reference phase detecting section estimates a current zero point of a current waveform on the basis of the measurements. Subsequently, a control section, upon receipt of an opening/closing command, an opening phase control operation using an arbitrary time point after the current waveform estimation as a reference.

Phase control switching system

A switch for use in electric power includes a fixed contact, a moving contact performing a switching operation with respect to the fixed contact, a cylinder working with the moving contact, a piston slidably provided in the cylinder, a buffer chamber which is surrounded by the cylinder and the piston, and is filled with an arc-extinguishing gas, and a second insulating nozzle mounted to an end of the cylinder on the side of the fixed contact, wherein the arc-extinguishing gas in the buffer chamber is sprayed through the nozzle on an arc generating between the fixed contact and the moving contact at an opening time of the moving contact.

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Tokyo, Japan

Haruhiko Kohyama