Abstract: The voltage measuring device includes: a light source; a polarizer polarizing light emitted from the light source; a grounded conductor provided apart from a high-voltage conductor; a crystal end face electrode being out of contact with the grounded conductor and the high-voltage conductor; a Pockels cell transmitting light from the polarizer; an analyzer transmitting light reflected by the Pockels cell; a photodetector detecting light emitted from the analyzer; an intra-crystal electric field measurement unit converting voltage output by the photodetector into intra-crystal electric field; a bias electrode being out of contact with the crystal end face electrode; a bias supply; a bias supply control unit controlling the bias supply to keep internal electric field of the Pockels cell at zero; and a measurement voltage calculation unit obtaining voltage of the high-voltage conductor based on results output by the intra-crystal electric field measurement unit and the bias supply control unit.

Abstract: The voltage measuring device includes: a light source; a polarizer polarizing light emitted from the light source; a grounded conductor provided apart from a high-voltage conductor; a crystal end face electrode being out of contact with the grounded conductor and the high-voltage conductor; a Pockels cell transmitting light from the polarizer; an analyzer transmitting light reflected by the Pockels cell; a photodetector detecting light emitted from the analyzer; an intra-crystal electric field measurement unit converting voltage output by the photodetector into intra-crystal electric field; a bias electrode being out of contact with the crystal end face electrode; a bias supply; a bias supply control unit controlling the bias supply to keep internal electric field of the Pockels cell at zero; and a measurement voltage calculation unit obtaining voltage of the high-voltage conductor based on results output by the intra-crystal electric field measurement unit and the bias supply control unit.

Abstract: In a connecting device of an electrical apparatus in which a first solid insulator and a second solid insulator each molded as a solid insulator on a periphery of a center conductor are connected to each other via a flexible insulator, a high voltage electrode having an outer diameter larger than those of the center conductors is disposed in the second solid insulator, and a ground electrode having an inner diameter smaller than that of an outer ground layer of the second solid insulator and larger than the outer diameter of the high voltage electrode is disposed in the first solid insulator. Electric field directions at an interface between the first solid insulator and the flexible insulator and at an interface between the second solid insulator and the flexible insulator are directions along the respective interfaces.

Abstract: A stator coil accommodated in a slot of a rotary electric machine includes a coil conductor, a main insulating layer, a low resistance corona shield layer, and a stator coil extending outside the slot is provided with a first stator coil at the end of the low resistance corona shield layer has a first nonlinear resistance layer and a second nonlinear resistance layer partially overlapping with an end of the first nonlinear resistance layer, and a lower limit value of an electric resistivity of the second nonlinear resistance layer in a predetermined electric field is larger than an upper limit value of an electric resistivity of the first nonlinear resistance layer by one order of magnitude or more.

Abstract: A stationary induction apparatus includes a core, a winding wound around the core such that the core serves as a central axis, and an annular electrostatic shield disposed adjacent to at least one of ends of the winding in a direction along the central axis. The electrostatic shield includes a conductor and a second insulating coating that coats the conductor. The electrostatic shield has a potential lower than a highest potential in the winding.

Abstract: A plurality of windings each including an electric wire portion and a first insulating coating that coats the electric wire portion. A plurality of electrostatic shields each including a conductor and a second insulating coating that coats the conductor. A stationary induction apparatus satisfies at least one positional relationship among: a relationship in which an outer peripheral end of the conductor in each of the electrostatic shields is located inside an outer peripheral end of the electric wire portion of an adjacent winding among the windings, the adjacent winding being adjacent to the electrostatic shield in the direction extending along the central axis; and a relationship in which an inner peripheral end of the conductor in each of the electrostatic shields is located outside an inner peripheral end of the electric wire portion of the adjacent winding.

Abstract: A stator coil accommodated in a slot of a rotary electric machine includes a coil conductor, a main insulating layer, a low resistance corona shield layer, and a stator coil extending outside the slot is provided with a first stator coil at the end of the low resistance corona shield layer has a first nonlinear resistance layer and a second nonlinear resistance layer partially overlapping with an end of the first nonlinear resistance layer, and a lower limit value of an electric resistivity of the second nonlinear resistance layer in a predetermined electric field is larger than an upper limit value of an electric resistivity of the first nonlinear resistance layer by one order of magnitude or more.

Abstract: In a connecting device of an electrical apparatus in which a first solid insulator and a second solid insulator each molded as a solid insulator on a periphery of a center conductor are connected to each other via a flexible insulator, a high voltage electrode having an outer diameter larger than those of the center conductors is disposed in the second solid insulator, and a ground electrode having an inner diameter smaller than that of an outer ground layer of the second solid insulator and larger than the outer diameter of the high voltage electrode is disposed in the first solid insulator. Electric field directions at an interface between the first solid insulator and the flexible insulator and at an interface between the second solid insulator and the flexible insulator are directions along the respective interfaces.

Abstract: A partial discharge determination method and apparatus, and a partial discharge determination system capable of indicating how much margin is left before dielectric breakdown, in a lighting impulse withstand voltage test, and a power device for which whether partial discharge is caused is determined by them, and a method for manufacturing a power device including the partial discharge determination method. A low-pass filter receives an acoustic signal resulting from application of an impulse voltage and acquired by an acoustic emission sensor, and removes an electromagnetic noise superimposed on the acoustic signal. A mechanical oscillation removal unit removes a mechanical oscillation component of a device under test, from the acoustic signal resulting from application of the impulse voltage which is a high voltage, based on the mechanical oscillation component acquired in advance and included in the acoustic signal resulting from application of the impulse voltage which is a low voltage.

Abstract: A first opposing surface inclination angle of a protruding first solid insulating material of a first high-voltage device is smaller than a second opposing surface inclination angle of a dented second solid insulating material of a second high-voltage device. A hollow truncated-cone flexible insulating material of which the thickness before insertion between the first high-voltage device and the second high-voltage device is the same at every part and the elasticity modulus gradually increases from a small-diameter side toward a large-diameter side, or a hollow truncated-cone flexible insulating material of which the thickness before insertion gradually increases from a small-diameter side toward a large-diameter side and the elasticity modulus is the same at every part, is compressed and sandwiched between the first solid insulating material and the second solid insulating material.

Abstract: A stationary induction apparatus includes a core, a winding wound around the core such that the core serves as a central axis, and an annular electrostatic shield disposed adjacent to at least one of ends of the winding in a direction along the central axis. The electrostatic shield includes a conductor and a second insulating coating that coats the conductor. The electrostatic shield has a potential lower than a highest potential in the winding.

Abstract: A first opposing surface inclination angle of a protruding first solid insulating material of a first high-voltage device is smaller than a second opposing surface inclination angle of a dented second solid insulating material of a second high-voltage device. A hollow truncated-cone flexible insulating material of which the thickness before insertion between the first high-voltage device and the second high-voltage device is the same at every part and the elasticity modulus gradually increases from a small-diameter side toward a large-diameter side, or a hollow truncated-cone flexible insulating material of which the thickness before insertion gradually increases from a small-diameter side toward a large-diameter side and the elasticity modulus is the same at every part, is compressed and sandwiched between the first solid insulating material and the second solid insulating material.

Abstract: A plurality of windings each including an electric wire portion and a first insulating coating that coats the electric wire portion. A plurality of electrostatic shields each including a conductor and a second insulating coating that coats the conductor. A stationary induction apparatus satisfies at least one positional relationship among: a relationship in which an outer peripheral end of the conductor in each of the electrostatic shields is located inside an outer peripheral end of the electric wire portion of an adjacent winding among the windings, the adjacent winding being adjacent to the electrostatic shield in the direction extending along the central axis; and a relationship in which an inner peripheral end of the conductor in each of the electrostatic shields is located outside an inner peripheral end of the electric wire portion of the adjacent winding.

Abstract: A partial discharge determination method and apparatus, and a partial discharge determination system capable of indicating how much margin is left before dielectric breakdown, in a lighting impulse withstand voltage test, and a power device for which whether partial discharge is caused is determined by them, and a method for manufacturing a power device including the partial discharge determination method. A low-pass filter receives an acoustic signal resulting from application of an impulse voltage and acquired by an acoustic emission sensor, and removes an electromagnetic noise superimposed on the acoustic signal. A mechanical oscillation removal unit removes a mechanical oscillation component of a device under test, from the acoustic signal resulting from application of the impulse voltage which is a high voltage, based on the mechanical oscillation component acquired in advance and included in the acoustic signal resulting from application of the impulse voltage which is a low voltage.

Abstract: Each of a plurality of electrostatic shields includes an insulator portion and a conductor portion. The conductor portion includes a flat portion formed in an annular shape and a pair of protruding portions. The insulator portion is provided with a first housing portion housing the flat portion and a pair of second housing portions each housing a corresponding one of the pair of protruding portions. Each of the pair of protruding portions includes: a protruding end portion located along an inner surface of a corresponding one of the pair of second housing portions, and a center portion located adjacent to the protruding end portion. In each of the pair of protruding portions, the protruding end portion and the center portion are electrically connected to each other and are equal in electric potential to each other.

Abstract: Each of a plurality of electrostatic shields includes an insulator portion and a conductor portion. The conductor portion includes a flat portion formed in an annular shape and a pair of protruding portions. The insulator portion is provided with a first housing portion housing the flat portion and a pair of second housing portions each housing a corresponding one of the pair of protruding portions. Each of the pair of protruding portions includes: a protruding end portion located along an inner surface of a corresponding one of the pair of second housing portions, and a center portion located adjacent to the protruding end portion. In each of the pair of protruding portions, the protruding end portion and the center portion are electrically connected to each other and are equal in electric potential to each other.