Abstract: A direct-current interrupter in an embodiment includes a current-carrying path and a current-interrupting path connected in parallel to the current-carrying path. The current-carrying path includes a first switch and a second switch connected in series and a resistor connected in parallel to the second switch. The first switch has a predetermined first withstand voltage property and switches between conduction and non-conduction of current by using no semiconductor switch. The second switch has a second withstand voltage property lower in withstand voltage property than the first withstand voltage property and switches between conduction and non-conduction of current by using no semiconductor switch. The resistor protects the second switch from voltage to be applied to the second switch. The current-interrupting path includes a semiconductor switch and a current source connected in series and a non-linear resistor connected in parallel to a series connection of the semiconductor switch and the current source.

Abstract: According to one embodiment, a tank-type vacuum circuit breaker includes a tank, a vacuum valve provided in the tank, an insulating layer provided on an outer circumference of the vacuum valve, having a fixed side interface connecting portion and a movable side interface connecting portion, a grounding layer provided on an outer circumference of the insulating layer, a fixed side bushing having an interface connecting portion connected to the fixed side interface connecting portion, a fixed side porcelain tube to house the fixed side bushing, a movable side bushing having an interface connecting portion connected to the movable side interface connecting portion, a movable side porcelain tube to house the movable side bushing, and insulation gas filled in the tank, at an approximately atmospheric pressure.

Abstract: A highly efficient electromagnetic actuator which can reduce leakage of the magnetic flux is provided. The electromagnetic actuator comprises a first coil 31, a movable body 2 adapted to move on the central axis of the first coil 31, a first stator 11 covering the top face, bottom face and outer peripheral face of the first coil 31, and a permanent magnet 15 adapted to firmly latch the movable body 2 at one end point of its movable range. A second stator 12 adapted to control the magnetic flux generated from the permanent magnet 15 is provided in succession with the first stator 11. By providing the second stator 12, when releasing the movable body 2 from its firmly latched state, the permanent magnet 15 is not inversely excited or demagnetized.

Abstract: A highly efficient electromagnetic actuator which can reduce leakage of the magnetic flux is provided. The electromagnetic actuator comprises a first coil 31, a movable body 2 adapted to move on the central axis of the first coil 31, a first stator 11 covering the top face, bottom face and outer peripheral face of the first coil 31, and a permanent magnet 15 adapted to firmly latch the movable body 2 at one end point of its movable range. A second stator 12 adapted to control the magnetic flux generated from the permanent magnet 15 is provided in succession with the first stator 11. By providing the second stator 12, when releasing the movable body 2 from its firmly latched state, the permanent magnet 15 is not inversely excited or demagnetized.

Abstract: A needle 2 includes a plunger member 21 and a collar member 22, and is provided to be reciprocable from a latch position to a latch release position inside a stator 1. A first magnet coil 31 has sufficient electromagnetic power to put in a latch state the needle 2 which is in a latch release state on energization. A permanent magnet 4 has sufficient absorption power for absorbing a collar member 22 of the needle 2 put in the latch state by the electromagnetic power of the first magnet coil 31 and maintaining the latch state even when the first magnet coil 31 is in a non-energized state. A second magnet coil 32 can diminish magnetic fluxes of the permanent magnet 4 and change the needle 2 from the latch state to the latch release state on energization. Thus, energy efficiency is improved by varying how to energize the magnet coils according to the state of a load side.