Abstract: An arrangement to control an electrical property of a medium or high voltage AC system including a number n of phases with n being at least two includes a number n of phases, each phase including a series connection of at least two electrical elements with an intermediate connection point between each pair of the at least two electrical elements, where each of the n phases of the arrangement is connected on one side to an original common neutral point and on the other side to one of the n phases of the AC system. The arrangement further includes a number of first switchable interconnections, where the first switchable interconnections are each arranged between two intermediate connection points of two of the n phases of the arrangement, and at least one control unit arranged to control the first switchable interconnections.

Abstract: An exemplary medium or high voltage switch has a first set of contact elements and a second set of contact elements. Each contact element includes an insulating carrier carrying conducting elements. In the closed state of the switch, the conducting elements align to form one or more current paths between terminals of the switch along an axial direction. For opening the switch, the contact elements are mutually displaced by means of one or two drives along a direction perpendicular to the axial direction. The switching arrangement is arranged in a fluid-tight housing in a gas of elevated pressure or in a liquid. The switch has a high voltage withstand capability and fast switching times.

Abstract: A DC current path for DC power transmission includes at least a first switching element and a second switching element connected in series. A resonance circuit is configured to be connectable in parallel to the series connection of the at least one first switching element and second switching element by means of a switch.

Abstract: An exemplary medium or high voltage switch has a first set of contact elements and a second set of contact elements. Each contact element includes an insulating carrier carrying conducting elements. In the closed current-carrying state of the switch, the conducting elements align to form one or more current paths between terminals of the switch along an axial direction. For opening the switch, the contact elements are mutually displaced by through two drives along a direction perpendicular to the axial direction. The switching arrangement is arranged in a fluid-tight housing in a gas of elevated pressure or in a liquid. The switch has a high voltage withstand capability and fast switching times.

Abstract: An arrangement to control an electrical property of a medium or high voltage AC system including a number n of phases with n being at least two includes a number n of phases, each phase including a series connection of at least two electrical elements with an intermediate connection point between each pair of the at least two electrical elements, where each of the n phases of the arrangement is connected on one side to an original common neutral point and on the other side to one of the n phases of the AC system. The arrangement further includes a number of first switchable interconnections, where the first switchable interconnections are each arranged between two intermediate connection points of two of the n phases of the arrangement, and at least one control unit arranged to control the first switchable interconnections.

Abstract: A device for breaking DC currents exceeding 2500 A has a resonance circuit connected in parallel with an interrupter and a surge arrester connected in parallel with the resonance circuit. The resonance circuit has a series connection of a capacitor and an inductance. The relationship of the capacitance in ?F to the inductance in ?H of the resonance circuit is ?1.

Abstract: An apparatus for reactive power compensation in an ac medium voltage power network. The apparatus includes a common connection; a first branch including a first switch, and a first capacitor; and a second branch including a second switch and a second capacitor.

Abstract: A device for reduction of the voltage derivative for an electrical component connected to an electric conductor via an electric bushing. The device protects an electrical component in an electrical apparatus against high voltage derivatives.

Abstract: A rotating electric motor for operating an electric component. The motor is arranged for an operating movement during a limited predetermined angular motion of the rotor of the motor. An electric drive circuit is arranged for the winding of the motor. The electric circuit exhibits at least one branch including an electric energy bank and a thyristor, which are connected in series with the motor winding. Also, a method for breaking, a use of the motor, and an electric switch provided with the motor.

Abstract: An apparatus for reactive power compensation in an ac medium voltage power network. The apparatus includes a common connection; a first branch including a first switch, and a first capacitor; and a second branch including a second switch and a second capacitor.

Abstract: An electric network for generation and transmission of electric power, including a power generating part, a point of common connection for the power generating part, a transmission link, a load network, and a reactive power compensator. The transmission link is coupled between the point of common connection and a grid connection point at the load network. The reactive power compensator is coupled to transmission link. The power generating part includes at least one wind turbine with an electric generator of induction type, coupled to the point of common connection. The reactive power compensator includes a capacitor bank and in parallel coupling to the capacitor bank a controllable inductor having a magnetic core, a main winding for alternating current, and a DC-control winding for direct current. The DC-control winding for control of the magnetic flux is set up by the main winding via orthogonal magnetization of the core.

Abstract: An electric device including an electric switch having a plurality of contact members arranged in series to form a plurality of breaking points arranged in series. One of the contact members at each breaking point is movable. A drive is arranged to actuate each movable contact member. The drive is arranged to effect simultaneous movement of the movable contact members. A commutation circuit is connected in parallel with the electric switch. Each contact member constitutes a part of a contact element, which contact elements are arranged in series. The contact elements have conducting and insulating parts. Every second contact element is movable in relation the others so that movement effects a breaking or closing position of the electric switch. The invention also includes a current limiter such as an electric device and also an electric power network provided with such a current limiter.

Abstract: A rotating electric motor for operating an electric component. The motor is arranged for an operating movement during a limited predetermined angular motion of the rotor of the motor. An electric drive circuit is arranged for the winding of the motor. The electric circuit exhibits at least one branch including an electric energy bank and a thyristor, which are connected in series with the motor winding. Also, a method for breaking, a use of the motor, and an electric switch provided with the motor.

Abstract: An electric network for generation and transmission of electric power, including a power generating part, a point of common connection for the power generating part, a transmission link, a load network, and a reactive power compensator. The transmission link is coupled between the point of common connection and a grid connection point at the load network. The reactive power compensator is coupled to transmission link. The power generating part includes at least one wind turbine with an electric generator of induction type, coupled to the point of common connection. The reactive power compensator includes a capacitor bank and in parallel coupling to the capacitor bank a controllable inductor having a magnetic core, a main winding for alternating current, and a DC-control winding for direct current. The DC-control winding for control of the magnetic flux is set up by the main winding via orthogonal magnetization of the core.

Abstract: An electric plant with a safety device, a method for remedying faults in a switchgear installation, and the use of a closing contact to provide security against faults. The plant includes a switchgear installation, consumer loads connected to the switchgear installation, and at least one feeder cable to the switchgear installation. The plant provides a strong consumer network that still has a high degree of safety against damage caused by short-circuiting faults. The plant includes at least two feeder cables, each connected to its own current source such as a transformer or a generator. At least one of the feeder cables is connected by a branch cable to ground. The branch cable is provided with a closing contact, which is normally open. The closing contact is arranged to be activated, i.e. to quickly close the connection to ground, in the event of short-circuiting in the switchgear installation.

Abstract: A fault current limiting system includes switching means for providing a fast switching operation; a parallel current path comprising a limiting fuse; and a switching system to automatically replace a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred. A method of limiting fault current includes providing a fast switching operation; providing a parallel current path comprising a limiting fuse; and automatically replacing a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred.

Abstract: A fault current limiting system includes switching means for providing a fast switching operation; a parallel current path comprising a limiting fuse; and a switching system to automatically replace a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred. A method of limiting fault current includes providing a fast switching operation; providing a parallel current path comprising a limiting fuse; and automatically replacing a blown set of fuses with an unblown set of fuses after a fault current limiting operation has occurred.

Abstract: The invention relates to an electric device comprising an electric switch (3) having a plurality of contact members arranged in series to form a plurality of breaking points arranged in series. One of the contact members at each breaking point is movable. A drive means (9) is arranged to actuate each movable contact member. The drive means (9) is arranged to effect simultaneous movement of the movable contact members. In accordance with this invention a commutation circuit (2) is connected in parallel with the electric switch (3). Each contact member constitutes a part of a contact element, which contact elements are arranged in series. The contact elements have conducting and insulating parts. Every second contact element is movable in relation the others so that moement effects a breaking or closing position of the electric switch. The invention also relates to a current limiter comprising such an electric device and also an electric power network provided with such a current limiter.

Abstract: A controllable inductor comprises at least a tubular core, a main winding surrounding the core and a control winding passing substantially axially through the core. A yoke of a material having a high magnetic permeability is arranged to extend outside the core and the main winding and together with the core form a closed loop having at the most small air gaps for a main magnetic flux generated in the core by a current in the main winding and extending substantially axially to the core. The control winding comprises first plates of a material having a good electric conductivity extending substantially axially through the core.

Abstract: A controllable inductor comprises at least a tubular core (3), a main winding (1) surrounding the core and a control winding (4) passing substantially axially through the core. It also comprises a yoke (19) of a material having a high magnetic permeability arranged to extend outside the core and the main winding and together with the core form a closed loop having at the most small air gaps for a main magnetic flux generated in the core by a current in said main winding and extending substantially axially to the core. The control winding comprises first plates of a material having a good electric conductivity extending substantially axially through the core.