Kabushiki Kaisha Toshiba

Sony Corporation

Yoshimasa Sato

Minoru Saito

Hiroyuki Maehara

Tadashi Koshizuka

Hiroshi Kusuyama

Shiro Maruyama

Koichi Futagami

Kenji Yamazaki

Nobuyuki Takahashi

Susumu Nishiwaki

Taizo Takiguchi

Minoru Saitoh

Keisuke Udagawa

Tadashi Koshiduka

Tsuyoshi Kokumai

Koso Kashima

According to one embodiment, there is provided an inrush current suppression apparatus that suppresses an inrush current generated when shunt capacitors are connected to a power system, the apparatus including a voltage measurement unit measuring power source voltages, a current measurement unit measuring circuit breaker currents, a polarity determination unit determining the polarities of residual voltages, a phase section detector detecting a phase section in which the polarities of the residual voltages match the polarities of the power source voltages, and a circuit breaker closing unit closing the circuit breaker within the phase section.

Inrush current suppression apparatus

According to one embodiment, there is provided an inrush current suppression apparatus that suppresses an inrush current generated when shunt capacitors are connected to a power system. The apparatus includes a power supply voltage measurement unit measuring a power supply voltage, a circuit breaker current measurement unit measuring a circuit breaker current, a residual voltage polarity determination unit determining the polarities of three phases of a residual voltage, a specific phase determination unit determining a specific phase, a closing phase detector detecting a closing phase, and a circuit breaker closing unit closing the circuit breaker in the closing phase.

A residual magnetic flux estimation deviceincludes a DC power-source control devicewhich controls a DC power sourceto apply a DC voltage across two terminals of a &#x394; connection that is a secondary winding or a tertiary winding, a voltage measuring devicewhich measures a terminal voltage at the primary side of a three-phase transformera computing devicethat determines a phase having a high voltage between the two phases other than the phase to which the voltage is applied, and a residual magnetic flux measuring devicethat measures a phase-to-phase residual magnetic flux between the two phases other than the high-voltage phase, and estimates a measured value of the phase-to-phase residual magnetic flux as a maximum residual magnetic flux in the measurement-target three-phase transformer.

Method of estimating the residual magnetic flux of transformer and residual magnetic flux estimation device

A switching controller for circuit breaker in which a switching control arithmetic operation unit performs arithmetic operations to determine for each circuit breaker a synchronous delay count value which is sent to each switching command control unit of the corresponding circuit breaker, which upon receiving a switching command signal from a superordinate device, counts the synchronous delay count value D, to turn on a semiconductor switch of the switching command output unit after counting completes. The switching command signal (circuit breaker drive current) is output after the synchronous switching control to the circuit breaker drive coil of the circuit breaker. The switching controller can implement cost saving and space saving, even if switching of a circuit breaker in a lower branch system, such as a power distribution system, is controlled.

Switching controller and switching control system for circuit breaker

In some embodiments, a method is disclosed that includes measuring a waveform of a power source side voltage of a circuit breaker; measuring a waveform of a transmission line side voltage of the circuit breaker; calculating a waveform of a voltage between contacts of the circuit breaker that is a difference between the waveform of the power source side voltage and the waveform of the transmission line side voltage; calculating a waveform of an absolute value of the waveform of the voltage between contacts; extracting a waveform of a component in a frequency band which is lower than a frequency of the power source and higher than a frequency of a DC component from the waveform of the absolute value; detecting a cycle of the extracted waveform; and closing the circuit breaker based on the cycle.

Overvoltage suppressing device

An overvoltage suppression device which suppresses overvoltage that occurs when breakers which turn on/off the connection between a power source bus and a power transmission line, are turned on after the breakers are turned off. The overvoltage suppression device measures the waveform of voltage on the side of the power source and the voltage on the side of the power transmission line, and extracts the waveform of a component in a predetermined frequency band on the basis of the waveform obtained by multiplying the wave shape of the voltage on the side of the power source by the waveform of the voltage on the side of the power transmission line. The breakers are turned on on the basis of a cycle wherein the waveform is peaked.

Over-voltage suppression apparatus

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 first calculation part calculates the phase-to-phase steady-state magnetic flux of the three phases of the power supply. A second calculation part calculates the phase-to-phase residual magnetic flux of the three phases in the primary windings side of the transformer when the circuit breakers interrupt the transformer. A phase detection part detects a voltage phase at which polarity and magnitude of the calculated steady-state magnetic flux and residual magnetic flux coincide. Closing control part firstly causes only the circuit breakers of the two phases to close at the detected voltage phase, and then causes the circuit breaker of the remaining one phase to close.

Magnetizing inrush current suppression device for transformer and control method of same

Test pattern data is recorded on a track of the optical disc, and the other pattern data is recorded on the neighboring track. A focus bias value providing the minimum jitter amount when the test pattern data is reproduced with varying the focus bias, is obtained. Just focusing condition is attained by the focus servo using the focus bias. When the test pattern data is reproduced, the data of these neighboring track is also reproduced simultaneously because the pattern data of the type different from the test pattern data is also recorded on the neighboring track. Particularly, under the defocusing condition, crosstalk amount becomes larger because the beam shape is distorted. With reference to jitter amount, such a mistake that the defocusing condition is erroneously determined as the just focusing condition can be eliminated. That is, the focus servo signal providing the accurate just focusing condition can be obtained.

Growing community of inventors

Kawasaki, Japan

Yoshimasa Sato