Kabushiki Kaisha Toshiba

Minoru Saitoh

Hiroyuki Maehara

Tadashi Koshizuka

Shiro Maruyama

Tomonori Nishida

Keisuke Udagawa

Yoshimasa Sato

Shigeki Katayama

Noriyuki Nagayama

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

According to one embodiment, there is provided a magnetizing inrush current suppression apparatus including an interrupting phase detection unit that detects a phase when the transformer that converts a three-phase alternating-current voltage to a single-phase alternating-current voltage is disconnected, a single-phase alternating-current voltage measurement unit that measures the single-phase alternating-current voltage on the power system side of the circuit breaker, and a closing unit that closes the circuit breaker in the detected phase, based on the measured single-phase alternating-current voltage.

Magnetizing inrush current suppression apparatus

According to one embodiment, there is provided a breaker-phase-control switching system including a merging unit, a superordinate unit, and a circuit-breaker control unit. The circuit-breaker control unit includes a waveform-zero-point-calculation processing unit configured to calculate a current phase, based on absolute time kept by an internal clock and waveform data, and a predicted-breaker-operating-time-calculation processing unit configured to predict a predicted operating time. Further, a command-output-timing-determination processing unit is included which determines a timing for electrically conducting a coil from the absolute time, a preset target phase, a current phase, and a predicted operating time.

Breaker-phase-control switching system and circuit-breaker control unit

A current transducer system for measuring AC current in a high-voltage main circuit having a circuit breaker and a disconnecting switch in an integrated gas-insulated switchgear. The system comprises a current sensor for detecting the AC current and outputting an analog electric signal representing the AC current, the current sensor disposed near the circuit breaker. The system further comprises a sensor unit including an analog-to-digital converter for converting the analog electric signal to a digital electric signal, and an electric-to-optic converter for converting the digital electric signal to a digital optic signal, the sensor unit disposed near the circuit breaker. The system further comprises optic transmission means for transmitting the digital optic signal.

Growing community of inventors

Kamakura, Japan

Minoru Saitoh