Abstract: A voltage surge protection device for protection of a high voltage device includes a varistor having a first part and a second part separated by varistor material. The voltage surge protection device further includes an expandable member arranged to act on a movable electrical contact for short-circuiting the voltage surge protection device upon a threshold voltage being applied between the first part and the second part of the varistor. A high voltage circuit breakers includes one or more semiconductor devices connected in series and the voltage surge protection device connected in parallel thereto.

Abstract: A voltage surge protection device for protection of a high voltage device includes a varistor having a first part and a second part separated by varistor material. The voltage surge protection device further includes an expandable member arranged to act on a movable electrical contact for short-circuiting the voltage surge protection device upon a threshold voltage being applied between the first part and the second part of the varistor. A high voltage circuit breakers includes one or more semiconductor devices connected in series and the voltage surge protection device connected in parallel thereto.

Abstract: A land electrode for a high voltage direct current transmission system including a converter station with a grounding point. The land electrode is connected to the grounding point and includes a plurality of electrode sections. A line electrode includes a part interconnecting two electrode sections. The part of the line electrode exhibits a line resistance. Each electrode section includes at least one electrode element.

Abstract: A land electrode for a high voltage direct current transmission system including a converter station with a grounding point. The land electrode is connected to the grounding point and includes a plurality of electrode sections. Each electrode section includes at least one electrode element.

Abstract: Measuring equipment for forming a measured value for voltage representing an ac voltage on a high-voltage conductor. The measuring equipment includes capacitor equipment with a known capacitance for connection between the high-voltage conductor and ground potential. The measuring equipment further includes a current-measurer for sensing a capacitor current flowing through the capacitor equipment and for forming the measured value for voltage in dependence on the capacitor current.

Abstract: Measuring equipment for forming a measured value for voltage representing an ac voltage on a high-voltage conductor. The measuring equipment includes capacitor equipment with a known capacitance for connection between the high-voltage conductor and ground potential. The measuring equipment further includes a current-measurer for sensing a capacitor current flowing through the capacitor equipment and for forming the measured value for voltage in dependence on the capacitor current.

Abstract: A surge arrester comprising a stack of a plurality of cylindrical varistor blocks (10), preferably made of metal oxide, which are arranged one after the other in the axial direction of the varistor blocks between an upper end electrode (11) and a lower end electrode (12) and surrounded by an elongated, electrically insulating external casing (19) of rubber or other polymeric material. The end electrodes (11, 12) are interconnected by means of at least three clamping members (15) of insulating material to achieve the required contact pressure between the different elements (10-14) in the stack. Between the lower end electrode (12) and the first block (10) in the stack of varistors, there is arranged a pivot means comprising a centrally placed pivot member (17), projecting from the lower end electrode (12), said pivot member (17) making contact with a pressure plate (14), resting against the lowermost block (10) in the stack of varistors, to achieve articulation in all transverse directions.

Abstract: A surge arrester includes a stack of varistor blocks (10), for example of zinc oxide, arranged between two end electrodes (11, 12) in an elongated insulating casing (23) of polymeric material, for example silicone rubber. The varistor blocks and the electrodes are axially surrounded by compression loops (14-17) of insulating material for providing the necessary contact pressure between the different elements (10, 11, 12) in the varistor stack. The varistor stack (10) and the compression loops are radially surrounded by a bursting-preventive bandage (21) of insulating material with openings (22) for pressure relief in case of internal short circuit in the surge arrester.

Abstract: A surge arrester with an elongated polymer housing (1) includes a stack of arrester elements (2), for example of zinc oxide. To limit the radial voltage stress which may arise in the polymer material upon pollution, the polymer housing (1) is provided on the outside with field-equalizing control electrodes (6) in the form of bands or rings of metal at regular distances along the arrester. The control electrodes (6) are electrically connected to the ZnO stack (2, 3) inside the housing (1).

Abstract: A surge arrester arrangement comprising includes a surge arrester (4) and a cut-out device (6) arranged in series with the arrester for automatic disconnection of the arrester in the event of arrester failure. The arrester arrangement is intended to be connected in parallel with an insulator (2) arranged for suspension of a power line (1) from a power line tower (3). The surge arrester (4) is connected to the power line (1) via a connecting link (5) in the form of a flexible electric conductor (10) enclosed in a tube of, for example, aluminium, which is divided into several parts, A helical spring (8) which, for example, may be arranged inside the tube, keeps the connecting link at insulation distance from the power line (1) when the arrester has become disconnected by means of the cut-out device (6).

Abstract: The invention relates to a surge arrester assembly with a plurality of parallel-connected arrester units (1) with polymer casing mounted in a rack. The lower and upper parts of the rack consist of bars (4a, 4b) of, for example, aluminium, which are included in the electric circuit. The bars are retained by, for example, support insulators (6) of porcelain or polymer material. The mechanical retention of the stacks of ZnO blocks of the arrester units (1) and the necessary contact pressure between the blocks are ensured by the rack structure. The electrical connections (23, 24) to the rack are arranged in such a way that, if a fault causing a short circuit in one of the block stacks occurs, the arc produced is blown by the current forces along the bars to the opposite end, where arcing horns (38) of a current-resistant material, for example steel, are arranged and where the arc may burn in a controlled manner without involving a risk to the environment. (FIG.