Abstract: A power conversion system including: a self-excited power converter that converts power between an alternating-current (AC) power system and a direct-current (DC) line; an AC circuit breaker disposed between the AC power system and the self-excited power converter; an arrester connected between the DC line and a ground or between an AC line and the ground, the AC line connecting the AC circuit breaker and the self-excited power converter; and a control device. The control device causes the self-excited power converter to stop a switching operation when the control device detects a ground fault accident on the DC line, and opens the AC circuit breaker after the self-excited power converter stops the switching operation.

Abstract: An objective is to prevent excessive temperature decrease of cooling water and to reduce energy loss by a heater. A water-cooled electrical apparatus includes an electrical device 2 placed indoors, a pump 3 for circulating cooling water for cooling the electrical device, a cooler 5, placed outdoors, for cooling the cooling water, a heater 6 for heating the cooling water, and a main pipe 4 forming a closed loop so that the cooling water circulates through the electrical device, the pump, the cooler, and the heater. The water-cooled electrical apparatus further includes a bypass pipe 11 bypassing between bifurcations 9 and 10, provided at inlet and outlet sides of the cooler, for flow-dividing the cooling water, and at least one of a first flow amount control valve 7 provided along the main pipe between the bifurcations, and a second flow amount control valve 12 provided along the bypass pipe.

Abstract: An inverter apparatus converts a DC power of a capacitor charged via a rectifier circuit connected to a first AC power system into an AC power, and supplies the AC power to a second AC power system. The inverter apparatus includes a discharge circuit, a control circuit, a trigger circuit, a first voltage-sag detection circuit, a control power circuit, and a second voltage-sag detection circuit. When the second voltage-sag detection circuit detects a voltage sag of the control power circuit below a threshold, the trigger circuit generates a discharge command signal for causing the discharge circuit to discharge a charge from the capacitor.

Abstract: A SVC control section detects a bus voltage from an instrument transformer, and adjusts reactive power generated by a SVC according to the detected bus voltage. A cooperative control section generates a control command for controlling the interconnection and parallel-off of a phase lead capacitor and a phase lag reactor on the basis of the amount of reactive power generated by the SVC and the bus voltage detected by the instrument transformer and a voltage sensor. A voltage comparator compares the bus voltage with a predetermined threshold voltage set to a voltage lower than a lower limit value of a steady state fluctuation range of the bus voltage and outputs the comparison result to a circuit breaker control section. When the bus voltage is lower than the threshold voltage, the circuit breaker control section locks the control command from the cooperative control section.

Abstract: An inverter apparatus converts a DC power of a capacitor charged via a rectifier circuit connected to a first AC power system into an AC power, and supplies the AC power to a second AC power system. The inverter apparatus includes a discharge circuit, a control circuit, a trigger circuit, a first voltage-sag detection circuit, a control power circuit, and a second voltage-sag detection circuit. When the second voltage-sag detection circuit detects a voltage sag of the control power circuit below a threshold, the trigger circuit generates a discharge command signal for causing the discharge circuit to discharge a charge from the capacitor.

Abstract: A light wavefront measuring apparatus (2, 2a, 42) includes a separating element (7a, 47a) for separating a flux of light which exits from an optical head (1, 31) into a first beam and a second beam, a first interference fringe display section (21, 21a) for displaying interference fringes formed from the first beam, a Dove prism (13, 53) for rotating a wavefront of the second beam around its optical axis (AX2), and a second interference fringe display section (22, 22a) for displaying interference fringes formed from the second beam which passed through it. In adjustment of the light source device, position of a collimator (5) in the optical head (1, 31) is adjusted in optical axis direction so as to approximate the interference fringe patterns displayed in the interference fringe display sections (21, 22, 21a, 22a) each other.

Abstract: A SVC control section detects a bus voltage from an instrument transformer, and adjusts reactive power generated by a SVC according to the detected bus voltage. A cooperative control section generates a control command for controlling the interconnection and parallel-off of a phase lead capacitor and a phase lag reactor on the basis of the amount of reactive power generated by the SVC and the bus voltage detected by the instrument transformer and a voltage sensor. A voltage comparator compares the bus voltage with a predetermined threshold voltage set to a voltage lower than a lower limit value of a steady state fluctuation range of the bus voltage and outputs the comparison result to a circuit breaker control section. When the bus voltage is lower than the threshold voltage, the circuit breaker control section locks the control command from the cooperative control section.

Abstract: A light wavefront measuring apparatus (2, 2a, 42) includes a separating element (7a, 47a) for separating a flux of light which exits from an optical head (1, 31) into a first beam and a second beam, a first interference fringe display section (21, 21a) for displaying interference fringes formed from the first beam, a Dove prism (13, 53) for rotating a wavefront of the second beam around its optical axis (AX2), and a second interference fringe display section (22, 22a) for displaying interference fringes formed from the second beam which passed through it. In adjustment of the light source device, position of a collimator (5) in the optical head (1, 31) is adjusted in optical axis direction so as to approximate the interference fringe patterns displayed in the interference fringe display sections (21, 22, 21a, 22a) each other.

Abstract: An optical recording and reproducing apparatus for optically recording and reproducing information on and from a disk includes a light source for generating a parallel beam. A movable optical system condenses the parallel beam from the light source on the disk, splits the beam into two different beams, and moves in the radial direction of the disk. A split-beam detecting device has two light receiving surfaces which receive part of the two different beams obtained in the movable optical system. A and a control device effects tracking control by moving the movable optical system in the radial direction of the disk in accordance with respective detection signals output from the two light receiving surfaces.

Abstract: A wavelength selective optical recording and reproducing method includes an optical recording and reproducing step of information composed of time series signals on a recording medium having recording tracks as position series signals with light having a variable wavelength while switching the wavelength between predetermined values.

Abstract: An optical recording and reproducing apparatus includes a light source for generating a parallel beam. A movable optical system condenses the parallel beam from the light source on the disk, splits the beam reflected by the disk into a first and a second beam, spatially inverts the second beam, and moves in the radial direction of the disk. A first split-beam detecting device has two light receiving surfaces which receive the first beam. A second split-beam detecting device has two light receiving surfaces which receive the second beam inverted in the movable optical system. A control device performs tracking control by moving the movable optical system in the radial direction of the disk in accordance with detection signals output from the first and second split-beam detecting devices.

Abstract: An optical head for use in an optical information recording/reproducing apparatus includes an optical system comprising a plurality of optical elements including a light-emitting element, and a casing which securely mounts at least part of the optical elements. The casing is provided with a vibration damping material which is effective to damp vibrations of the casing.

Abstract: The present invention relates to an optical recording and/or reproducing apparatus which optically carries out operations of recording and/or reproducing of information on a data carrier, by irradiating a beam from an optical head to the data carrier. In the apparatus according to the present invention, the angle between the optical axis of the beam from the optical head and the surface of said data carrier is detected, and a temperature adjusting device brings about a difference in temperature between both surfaces of the data carrier on the basis of the detected result in respect to the angle. Then, the difference in temperature generates a thermal strain, and this thermal strain functions to cancel the strain which the data carrier has previously had. As a result, the surface of the data carrier is kept on a level, so that this surface can be vertical to the optical axis of the beam from the optical head.

Abstract: A magneto-optic information-carrying medium comprises three magnetic layers. A magnetic bias field is generated by a third layer which is premagnetized in the direction parallel to the thickness thereof.

Abstract: A focusing error detecting apparatus comprises an objective lens system for focusing a ray flux on a surface of an optical recording disk, two photo detectors, an optical means including the lens system and a beam splitter, for focusing a ray flux reflected from the optical recording disk so that the ray flux comes to the middle of a space formed between the two photo detectors when the focal point is formed on the optical recording disk, a combination of two interruption/deflection elements and a control device for switching the ray flux transmitted from the optical recording disk at the two positions which correspond to said two photo detectors, two sampling/holding circuits respectively hold differences of output of the two photo detectors in correspondence to the switching operations of the interruption/deflection elements and the control device, and a subtracting circuit for outputting a focusing error signal on the basis of the outputs of the sampling/holding circuit.

Abstract: Provided is an optical recording and reproducing apparatus in which a collimator lens collimates divergent light fluxes from a light source to emit parallel light fluxes and then an objective lens converges the parallel light fluxes onto an information carrier. The collimator lens comprises a first lens having a first predetermined focal distance and a second lens having a second predetermined focal distance which is longer than the first predetermined focal distance. The second lens can be moved in the optical-axis direction so as to adjust the relative position of the collimator lens and the light source.

Abstract: An information-carrying medium with first, second and third ferromagnetic layers is enclosed in a housing, in which an initializing magnet is disposed. The second layer of the information-carrying medium is magnetized by the initializing magnet premagnetized in a uniform direction and is used as a bias layer.

Abstract: An information-carrying medium having the form of a disc is rotated around a central axis. The temperature of the disc is controlled by a temperature-adjusting element facing the surface of the disc.

Abstract: Information is recorded by creating recording hole at a predetermined wavelength position on a memory element with a characteristic of wavelength selective optical data storage. Because the memory element is pit-like, it causes diffraction of a light beam transmitted through or reflected by it. The diffracted beams are detected for positioning a beam spot right on the selected memory element.

Abstract: A recording medium for wavelength selective optical data storage has at least one memory element on which information is recorded by creating recording holes on the absorption spectrum thereof. The spectrum has at least one prerecorded hole for identifying the wavelength positions of the recording holes.