Abstract: In a DC feed system configured by a plurality of DC electrical circuits being combined, when an arc fault occurs, it is difficult to identify a DC electrical circuit in which an arc has occurred. For this reason, a DC electrical circuit protection apparatus includes: a plurality of DC electrical circuits, each of which has a current sensor provided in at least one of a positive or a negative electrical path and has arc noise absorbing mechanism on the upstream side of the current sensor; and an arc detection device which compares respective arc noise signal strengths of the DC electrical circuits from current signals detected by the current sensors of the DC electrical circuits, and based on the signal strengths, identifies a circuit in which an arc has occurred, wherein a DC electrical circuit in which an arc has occurred is identified.

Abstract: In an electromagnetically moving device 100, a magnetic-flux variation measuring unit 3 is placed at a position which is outside a closed magnetic path established when a movable core 6 and a stationary core 5 are being attached to each other due to permanent magnets 7, and at which a leakage magnetic-flux variation due to movement of the movable core 6 can be measured, so that a behavior of a movable part in a switch, etc. is estimated such that an inflection point time is calculated from the measurement of time-series data of the magnetic-flux variation.

Abstract: In a DC feed system configured by a plurality of DC electrical circuits being combined, when an arc fault occurs, it is difficult to identify a DC electrical circuit in which an arc has occurred. For this reason, a DC electrical circuit protection apparatus includes: a plurality of DC electrical circuits, each of which has a current sensor provided in at least one of a positive or a negative electrical path and has arc noise absorbing mechanism on the upstream side of the current sensor; and an arc detection device which compares respective arc noise signal strengths of the DC electrical circuits from current signals detected by the current sensors of the DC electrical circuits, and based on the signal strengths, identifies a circuit in which an arc has occurred, wherein a DC electrical circuit in which an arc has occurred is identified.

Abstract: This current detection device is configured from: an annular magnetic material core that forms a closed magnetic path around a pair of conducting wires in which conduction currents flow; an excitation coil wound on the magnetic material core; an oscillation circuit unit that applies a rectangular wave output voltage to the excitation coil; a power supply unit that supplies power to an operation amplifier that generates the rectangular wave output voltage in the oscillation circuit unit; and a difference current calculation unit, which detects a power supply current flowing from the power supply unit to the operation amplifier, and which calculates a difference current between the conduction currents flowing in the pair of conducting wires. Consequently, excellent noise resistance is achieved, and the configuration of the current detection device is simplified.

Abstract: This current detection device is configured from: an annular magnetic material core that forms a closed magnetic path around a pair of conducting wires in which conduction currents flow; an excitation coil wound on the magnetic material core; an oscillation circuit unit that applies a rectangular wave output voltage to the excitation coil; a power supply unit that supplies power to an operation amplifier that generates the rectangular wave output voltage in the oscillation circuit unit; and a difference current calculation unit, which detects a power supply current flowing from the power supply unit to the operation amplifier, and which calculates a difference current between the conduction currents flowing in the pair of conducting wires. Consequently, excellent noise resistance is achieved, and the configuration of the current detection device is simplified.

Abstract: In an electromagnetically moving device 100, a magnetic-flux variation measuring unit 3 is placed at a position which is outside a closed magnetic path established when a movable core 6 and a stationary core 5 are being attached to each other due to permanent magnets 7, and at which a leakage magnetic-flux variation due to movement of the movable core 6 can be measured, so that a behavior of a movable part in a switch, etc. is estimated such that an inflection point time is calculated from the measurement of time-series data of the magnetic-flux variation.

Abstract: This current detection device is configured from: an annular magnetic material core that forms a closed magnetic path around a pair of conducting wires in which conduction currents flow; an excitation coil wound on the magnetic material core; an oscillation circuit unit that applies a rectangular wave output voltage to the excitation coil; a power supply unit that supplies power to an operation amplifier that generates the rectangular wave output voltage in the oscillation circuit unit; and a difference current calculation unit, which detects a power supply current flowing from the power supply unit to the operation amplifier, and which calculates a difference current between the conduction currents flowing in the pair of conducting wires. Consequently, excellent noise resistance is achieved, and the configuration of the current detection device is simplified.