Abstract: The present invention relates to a method for controlling a motor-driven vacuum circuit breaker. The method comprises initiate opening (S100) the circuit breaker, wherein the circuit breaker moves with an average opening speed of a contact pair of the circuit breaker, from a closed position to an open position of the circuit breaker, and decelerating (S110) the opening speed of the contact pair to below the average opening speed before the open position is reached to avoid overshoot, and initiate closing (S120) the circuit breaker, wherein the circuit breaker moves with an average closing speed of the contact pair, from the open position to the closed position, and decelerating (S130) the closing speed of the contact pair to below the average closing speed before contact touch at the closed position, wherein the circuit breaker moves with the decelerated speed at contact touch. A motor-driven vacuum circuit breaker, a computer program and a computer program product are also presented.

Abstract: The present invention relates to a method for controlling a motor-driven vacuum circuit breaker. The method comprises initiate opening (S100) the circuit breaker, wherein the circuit breaker moves with an average opening speed of a contact pair of the circuit breaker, from a closed position to an open position of the circuit breaker, and decelerating (S110) the opening speed of the contact pair to below the average opening speed before the open position is reached to avoid overshoot, and initiate closing (S120) the circuit breaker, wherein the circuit breaker moves with an average closing speed of the contact pair, from the open position to the closed position, and decelerating (S130) the closing speed of the contact pair to below the average closing speed before contact touch at the closed position, wherein the circuit breaker moves with the decelerated speed at contact touch. A motor-driven vacuum circuit breaker, a computer program and a computer program product are also presented.

Abstract: The present invention relates to a method for controlling a motor-driven vacuum circuit breaker. The method comprises initiate opening (S100) the circuit breaker, wherein the circuit breaker moves with an average opening speed of a contact pair of the circuit breaker, from a closed position to an open position of the circuit breaker, and decelerating (S110) the opening speed of the contact pair to below the average opening speed before the open position is reached to avoid overshoot, and initiate closing (S120) the circuit breaker, wherein the circuit breaker moves with an average closing speed of the contact pair, from the open position to the closed position, and decelerating (S130) the closing speed of the contact pair to below the average closing speed before contact touch at the closed position, wherein the circuit breaker moves with the decelerated speed at contact touch. A motor-driven vacuum circuit breaker, a computer program and a computer program product are also presented.

Abstract: A method for controlling a circuit breaker, the circuit breaker is connected in a three-phase system having an inductive load, and the method includes a method for controlling a circuit breaker, the circuit breaker being connected in a three-phase system having an inductive load, the method includes opening a first phase of the three-phase system before a zero crossing of a current in the first phase, opening the second and third phases of the three-phase system a quarter period after opening the first phase, closing the first and second phase at a peak voltage of a voltage between the first and second phases, and closing the third phase a quarter period after closing the first and second phases. A circuit breaker controller is also presented.

Abstract: A method for controlling a circuit breaker, the circuit breaker is connected in a three-phase system having an inductive load, and the method includes a method for controlling a circuit breaker, the circuit breaker being connected in a three-phase system having an inductive load, the method includes opening a first phase of the three-phase system before a zero crossing of a current in the first phase, opening the second and third phases of the three-phase system a quarter period after opening the first phase, closing the first and second phase at a peak voltage of a voltage between the first and second phases, and closing the third phase a quarter period after closing the first and second phases. A circuit breaker controller is also presented.

Abstract: An electric power distribution switchgear is connected between an electric power grid and an electric power equipment. The switchgear includes a synchronized vacuum switching apparatus configured to break the current to the electric power equipment using a synchronized technique to avoid re-ignition during the breaking and thus any transients caused by such re-ignition; and a surge arrester arrangement connected to the electric power equipment, the surge arrester arrangement being designed and configured to only handle transients caused by the current chopping at the breaking. The surge arrester arrangement can be arranged remote from the electric power equipment, such as e.g. in the same casing as the synchronized vacuum switching apparatus.

Abstract: A passive electronic fuse for protecting a DC application in the event of a fault includes a first leg including a first winding of a mutual inductor and a switch device connected in series, a second leg including a second winding of the mutual inductor. The first leg and the second leg are connected in parallel and a self-inductance of the second winding is lower than a self-inductance of the first winding. The second leg further includes a capacitor connected in series with the second winding of the mutual inductor, and the switch device is a thyristor or a switch device with switching properties of a thyristor.

Abstract: An electric power distribution switchgear is connected between an electric power grid and an electric power equipment. The switchgear includes a synchronized vacuum switching apparatus configured to break the current to the electric power equipment using a synchronized technique to avoid re-ignition during the breaking and thus any transients caused by such re-ignition; and a surge arrester arrangement connected to the electric power equipment, the surge arrester arrangement being designed and configured to only handle transients caused by the current chopping at the breaking. The surge arrester arrangement can be arranged remote from the electric power equipment, such as e.g. in the same casing as the synchronized vacuum switching apparatus.

Abstract: A passive electronic fuse for protecting a DC application in the event of a fault includes a first leg including a first winding of a mutual inductor and a switch device connected in series, a second leg including a second winding of the mutual inductor. The first leg and the second leg are connected in parallel and a self-inductance of the second winding is lower than a self-inductance of the first winding. The second leg further includes a capacitor connected in series with the second winding of the mutual inductor, and the switch device is a thyristor or a switch device with switching properties of a thyristor.

Abstract: A transformer arrangement and transformer for mitigating transient voltage oscillations. The transformer included a transformer core enclosing at least one core leg. A winding is wound around one of the at least one core leg. The winding extends from a first winding terminal to a second winding terminal and includes a first winding section along a first conductor extending from the first winding terminal to a first intermediate end point, and a second winding section along a second conductor extending from a second intermediate end point to the second winding terminal. The transformer arrangement further includes an external passive electric component connected between the first intermediate end point and either the second intermediate end point or the second winding terminal arranged to decrease an effective difference between capacitive and inductive voltage distributions between the intermediate end points such that transient voltage oscillations in the winding are mitigated.

Abstract: A system for transient over voltage protection of a three-phase transformer. Two surge arresters are series connected across each winding of the transformer and the center point connection of the two surge arresters is electrically connected to a middle location of the winding. Three additional surge arresters are electrically connected from each phase to ground in the case of either a delta or Y connected transformer; and/or connected from a neutral point to ground in the case of a Y connected transformer. The system allows for all of the surge arresters to be packaged as an integrated surge arrester system to minimize induced transient over voltages and high stresses on the transformer winding due to internal resonances.

Abstract: A multi-terminal surge arrester which includes an active part extending along a longitudinal direction of the surge arrester, a first electrode resting against a first end of the active part, and a second electrode resting against a second end of the active part, which second end opposes the first end in the longitudinal direction of the surge arrester. The surge arrester further includes an insulating fixing device mechanically connecting and fixing the first electrode and the second electrode, and an insulating housing arranged around the active part. The active part includes at least two metal-oxide based varistor elements and a further electrode arranged between the at least two varistor elements, which further electrode provides an externally accessible electrical connection. Therein, the surge arrester is adapted for being insulated by surrounding air.

Abstract: A transformer arrangement and transformer for mitigating transient voltage oscillations. The transformer included a transformer core enclosing at least one core leg. A winding is wound around one of the at least one core leg. The winding extends from a first winding terminal to a second winding terminal and includes a first winding section along a first conductor extending from the first winding terminal to a first intermediate end point, and a second winding section along a second conductor extending from a second intermediate end point to the second winding terminal. The transformer arrangement further includes an external passive electric component connected between the first intermediate end point and either the second intermediate end point or the second winding terminal arranged to decrease an effective difference between capacitive and inductive voltage distributions between the intermediate end points such that transient voltage oscillations in the winding are mitigated.

Abstract: A system for transient over voltage protection of a three-phase transformer. Two surge arresters are series connected across each winding of the transformer and the center point connection of the two surge arresters is electrically connected to a middle location of the winding. Three additional surge arresters are electrically connected from each phase to ground in the case of either a delta or Y connected transformer; and/or connected from a neutral point to ground in the case of a Y connected transformer. The system allows for all of the surge arresters to be packaged as an integrated surge arrester system to minimize induced transient over voltages and high stresses on the transformer winding due to internal resonances.

Abstract: A multi-terminal surge arrester which includes an active part extending along a longitudinal direction of the surge arrester, a first electrode resting against a first end of the active part, and a second electrode resting against a second end of the active part, which second end opposes the first end in the longitudinal direction of the surge arrester. The surge arrester further includes an insulating fixing device mechanically connecting and fixing the first electrode and the second electrode, and an insulating housing arranged around the active part. The active part includes at least two metal-oxide based varistor elements and a further electrode arranged between the at least two varistor elements, which further electrode provides an externally accessible electrical connection. Therein, the surge arrester is adapted for being insulated by surrounding air.

Abstract: An apparatus is arranged to break an electrical current. The apparatus includes: a mechanical switch leg including a first winding of a mutual inductor and a mechanical switch connected in series; a semiconductor switch leg including a second winding of the mutual inductor and a semiconductor switch connected in series; and an overvoltage protection circuit. The mechanical switch leg and the semiconductor switch leg are connected in parallel and a self inductance of the second winding is lower than a self inductance of the first winding. A corresponding DC circuit breaker and AC current limiter are also presented.

Abstract: An apparatus is arranged to break an electrical current. The apparatus includes: a mechanical switch leg including a first winding of a mutual inductor and a mechanical switch connected in series; a semiconductor switch leg including a second winding of the mutual inductor and a semiconductor switch connected in series; and an overvoltage protection circuit. The mechanical switch leg and the semiconductor switch leg are connected in parallel and a self inductance of the second winding is lower than a self inductance of the first winding. A corresponding DC circuit breaker and AC current limiter are also presented.

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.