Abstract: In a rotating electrical machine a stator winding is formed of flexible cables inserted in an open stator in the stator core. The stator slots extend from a radially outermost yoke part of the stator core radially inwards towards the rotor, the stator slots being separated by teeth. The stator slots are shaped as double slots with shoulders arranged in the slot walls such that each cable in the winding is secured between the previous cable in the stator slot and, seen from the slot opening, the next shoulder situated outside that particular cable. In a method for manufacturing such a winding the first cable is inserted through the opening of the stator slot and pressed firmly into a cable slot arranged at the bottom of the stator slot and designed to retain the cable when it has been pressed in.

Abstract: A rotating electrical machine and method for making the machine, where the machine includes a high-voltage stator winding and elongated support devices for supporting the winding. The machine and method employ an arrangement of cable that is made of inner conductive strands, covered with a first semiconducting layer, which is covered with an insulating layer, which is covered with a second semiconducting layer. The cable is wound in slots in the stator such that separate cable lead-throughs are positioned in specific arrangements with respect to each other and in slots of the stator. The arrangement of the cable in the stator protects the integrity of the respective components in the cable and particularly the second semiconducting layer.

Abstract: In a rotating electrical machine a stator winding is formed of flexible cables inserted in an open stator in the stator core. The stator slots extend from a radially outermost yoke part of the stator core radially inwards towards the rotor, the stator slots being separated by teeth. The stator slots are shaped as double slots with shoulders arranged in the slot walls such that each cable in the winding is secured between the previous cable in the stator slot and, seen from the slot opening, the next shoulder situated outside that particular cable. In a method for manufacturing such a winding the first cable is inserted through the opening of the stator slot and pressed firmly into a cable slot arranged at the bottom of the stator slot and designed to retain the cable when it has been pressed in.

Abstract: The invention concerns a method for manufacturing an electrical insulator that includes a body (1) and a coating (5, 5a) of insulating material arranged on the body (1) where the coating is applied onto the body in a screw-like form or a helical-like form, whereby the coating is applied by extrusion directly on the body (1). In this way, the build-up trapped pockets of air between the applied coating and the body (1) is prevented, and good adhesion is achieved. The invention also concerns an apparatus for manufacturing an insulator as well as the use of the said method or apparatus for the manufacturing of a high voltage insulator.

Abstract: A rotating electric machine and method for manufacturing the same in which a high-voltage cable is wound in a stator so as to make a winding. A feature of the high-voltage cable is that the cable includes an inner semiconducting layer, a solid insulation material, and an outer semiconducting layer. A casting compound is supplied in a slot that holds the cable in the stator so as to avoid damaging an outer surface of the cable.

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 tape-formed or sheet-formed insulating material for use in windings and coils of electrical machines includes an insulating layer in the form of a homogeneous film of an organic polymer or in the form of a felt of a paper of fibres of an organic polymer and a protective layer coated on at least one side of the insulating layer which protects the insulating layer against degradation caused by corona. The protective layer comprises an organic polymer containing at least 10 percent by volume of a powdered filler in the form of chromium oxide, iron oxide or a mixture of chromium oxide and iron oxide. The filler preferably has an intrinsic resistivity of 10.sup.4 -10.sup.8 ohm m. The thickness of the protective layer and the total thickness of the protective layer, respectively, are preferably smaller than the thickness of the insulating layer and the resistivity of the protective layer is preferably in excess of 10.sup.10 ohm m.

Abstract: An electrical conductor is provided with an electrical insulation (11) surrounding the conductor (10) and a surrounding protective layer (12) which protects the insulation against degradation caused by corona. The protective layer consists of an organic polymer containing at least 10 percent by volume of a powdered filler in the form of chromium oxide, iron oxide, or a mixture of chromium oxide and iron oxide. The filler preferably has an intrinsic resistivity of 10.sup.4 -10.sup.8 ohm m. The thickness of the protective layer is preferably smaller than the thickness of the underlying insulation (11) and its resistivity preferably exceeds 10.sup.10 ohm m. The conductor is used, among other things, in windings and coils for electrical machines.

Abstract: A coil for arrangement in slots in a stator or rotor of an electrical machine, in particular a high voltage coil, comprising a bundle (17) of a plurality of conductors (18) located adjacent to each other and provided with a conductor insulation (19) for insulation of the conductors from each other as well as a main insulation (14) surrounding the bundle for insulation of the bundle against the machine slot. The main insulation consists of a wrapping of a tape- or sheet-formed insulating material wound in several layers around the bundle and comprising a layer with small mica flakes which, as well as the spaces between layers of mica flakes in the wrapping, contains a cured impregnating resin. At least that part of the impregnating resin located in the spaces between mica layers contains particles of a filler with an intrinsic thermal conductivity of at least 5 W/mK, such as aluminium oxide or boron nitride, and with a grain size of the particles of 0.1-15 .mu.m in at least 90 percent of the filler.

Abstract: A system for HVDC transmission comprises a conductor, stressed by d.c. voltage, which is insulated from a surrounded grounded casing by pressurized SF.sub.6 gas and along part of its length by at least one solid insulator supporting the conductor in the casing and in contact with the gas. By designing the solid insulator as a core of solid insulating material and a coating, provided thereon, with a high surface resistance, it is possible considerably to reduce the dimensions of the casing. The coating consists of a resinous binder containing a powdered filler in the form of chromium oxide or iron oxide, or a mixture of these substances. The coating preferably has a surface resistance between 10.sup.12 and 10.sup.18 ohm/.quadrature. at an electric field strength of 1 kV/mm.

Abstract: A press is adapted for the press tool it is to operate, by means of at least one pad of force-transmitting material formed in situ on a surface adapted to transmit the forming force to the press tool. The pad is formed by locating a tool substitute in the space intended for the tool, defining at least one volume between the tool substitute and the said surface adapted to transmit the forming force with a sealing means and injecting the pad forming material in liquid state into the said volume to allow the same to harden there preferably under a force equivalent to that which will be used in forming a blank when the substitute tool is replaced by the press tool.