Abstract: A network node for a substation or a local network station has a control transformer with a primary side and a secondary side, an input line connected to the primary side, and an output line connected to the secondary side. A protective switch is provided in the input line or in the output line, and a sensor detects an electrical parameter in the input line or in the output line and generate a measurement signal. A controller coupled to the control transformer, to the protective switch, and to the sensor, serves to operate the control transformer in dependence on the measurement signal such that the control transformer has a predetermined transmission ratio and open the protective switch in dependence on the measurement signal as soon as the control transformer has the predetermined transmission ratio.

Abstract: The invention relates to a switching arrangement (15) with a pre-selector (28) for a power transformer (10, 40) which has multiple windings (12, 14). The pre-selector is designed to optionally connect at least one first winding (12) to one of the two end contacts (30, 32) of at least one second winding (14). At least one first switch is arranged in the connection between the pre-selector (28) and the first winding (12), thereby allowing the pre-selector to be switched in an arc-free manner and thus in a gas-free manner as well.

Abstract: The invention relates to an on-load tap changer (2) according to the reactor switching principle for uninterrupted load switching between different tap windings of a tapped transformer (1), comprising: —an inductor (3) which is designed as an inductive transition reactance; —the inductor (3) being part of the on-load tap changer (2).

Abstract: The invention relates to a step switch, comprising a pre-selector and a fine selector. The invention is characterized in that the step switch has a connection (36) between the pre-selector and the fine selector (18), at least one coupling switch (38) being arranged in said connection. A pre-selector can be switched in a largely gas-free manner by means of said switchable connection with the aid of the fine selector.

Abstract: A network node (10) for a power grid (19), in particular, for a substation or a local network station, comprises a control transformer (11) with a primary side and a secondary side; an input line (12) connected to the primary side; an output line (13) connected to the secondary side; a protective switch (14) in the input line (12) or in the output line (13); a sensor (15) that can detect an electrical parameter in the input line (12) and/or in the output line (13) and generate a measurement signal; a controller (16) coupled to the control transformer (11), to the protective switch (14), and to the sensor (15), and that is formed such that it can operate the control transformer (11) in dependence on the measurement signal in such a manner that the control transformer (11) has a predetermined transmission ratio; it can operate the protective switch (14) in dependence on the measurement signal in such a manner that the protective switch (14) opens; with the protective switch (14) opening by the controller, be

Abstract: The invention relates to an on-load tap changer (2) according to the reactor switching principle for uninterrupted load switching between different tap windings of a tapped transformer (1), comprising: an inductor (3) which is designed as an inductive transition reactance; the inductor (3) being part of the on-load tap changer (2).

Abstract: The invention relates to a step switch, comprising a preselector and a fine selector. The invention is characterized in that the step switch has a connection (36) between the pre-selector and the fine selector (18), at least one coupling switch (38) being arranged in said connection. A pre-selector can be switched in a largely gas-free manner by means of said switchable connection with the aid of the fine selector.

Abstract: The invention relates to a switching arrangement (15) with a pre-selector (28) for a power transformer (10, 40) which has multiple windings (12, 14). The pre-selector is designed to optionally connect at least one first winding (12) to one of the two end contacts (30, 32) of at least one second winding (14). At least one first switch is arranged in the connection between the preselector (28) and the first winding (12), thereby allowing the pre-selector to be switched in an arc-free manner and thus in a gas-free manner as well.

Abstract: A method for operating an electrical power supply network is described. The power supply network has several levels of different voltages. The levels are interconnected by switches. A first switch is made so that the maximum interruptible short-circuit current of the first switch is smaller than the maximum flowing short-circuit current. In the event of failure, a test is made as to whether the short-circuit current presently flowing through the first switch is smaller than the maximum interruptible short-circuit current. The first switch will remain closed if this is not the case, and the first switch will be opened if this is the case.

Abstract: Mold-free resin-insulated coil windings are obtained by applying continuous fibers embedded in a quasi-solid-state epoxy-resin matrix, e.g. in the form of a tape, to the coil windings. The tape is locally heated up to the melting point of its polymer matrix, and is subsequently pressed against the winding body. The heated and fused resin of the tape, which is pressed onto the coil, flows under pressure into the voids and gaps between the coil windings and fills them up, thereby hermetically insulating the coil windings. After leaving the heating and pressing apparatus the fused epoxy resin becomes solid again. The resulting curing process is thus considerably simplified and shortened, compared to the state of the art.

Abstract: A method for operating an electrical power supply network is described. The power supply network has several levels of different voltages. The levels are interconnected by switches. A first switch is made so that the maximum interruptible short-circuit current of the first switch is smaller than the maximum flowing short-circuit current. In the event of failure, a test is made as to whether the short-circuit current presently flowing through the first switch is smaller than the maximum interruptible short-circuit current. The first switch will remain closed if this is not the case, and the first switch will be opened if this is the case.

Abstract: Mold-free resin-insulated coil windings are obtained by applying continuous fibers embedded in a quasi-solid-state epoxy-resin matrix, e.g. in the form of a tape, to the coil windings. The tape is locally heated up to the melting point of its polymer matrix, and is subsequently pressed against the winding body. The heated and fused resin of the tape, which is pressed onto the coil, flows under pressure into the voids and gaps between the coil windings and fills them up, thereby hermetically insulating the coil windings. After leaving the heating and pressing apparatus the fused epoxy resin becomes solid again. The resulting curing process is thus considerably simplified and shortened, compared to the state of the art.

Abstract: Bulk-modified potting composition based on a curable epoxy resin or on a mixture of these resins, where the resin or the mixture is composed of an epoxy resin, a hardener, where appropriate an accelerator, and also other additives, such as fillers, flexibilizers, and colorants, which potting composition (a) comprises a three-dimensionally crosslinked polysiloxane in disperse form and with a particle size in the range from 0.02 ?m to 50 ?m, which, where appropriate, has reactive groups which can react chemically with the epoxy resin and/or the hardener, (b) a selected linear or branched siloxane compound which has reactive groups which can react chemically with the epoxy resin and/or the hardener, and also, where appropriate, (c) a low-molecular-weight oligomeric siloxane compound, the use of the potting composition as an engineering material or as an insulating material, and the moldings and insulation produced therefrom.

Abstract: The subject of the invention is a high-voltage thick-film high rupturing capacity substrate fuse. The characteristic feature of the inventive fuse is that inside a tubular insulating casing /1/, which is closed at both ends with metal endocarps /2/ and filled with arc quenching medium /3/ there is located at least one insulating substrate /4/, along which there is placed at least one fuse element /5/ in the form of a thin conducting film and which has terminal areas /6/ at its ends, which areas are electrically connected with the end-caps by specially shaped contacts /7/ located inside the end-caps. The fuse element comprises a basic part formed by multiple identical V-shaped modules and two end modules forming electric connections between the basic part and the terminal areas.

Abstract: Curable epoxy resin composition comprising a polyepoxide; an anhydride hardener; a 1-substituted imidazole as catalyst; at least a diol in an amount of from 5 to 50 phr of said polyepoxide; a filler in an amount of from 200 to 600 phr of said polyepoxide and optionally additives. It shows improved crack resistance properties. An improved process for the fabrication of thermoset articles is also disclosed.

Abstract: The impact signaling system (9) is used in a high-voltage protective device and has a housing (13), a spring (16) which is arranged in the housing (13) and has a moveable end, an actuator (17) which can be passed out of the housing (13) and interacts with the moveable end of the spring (16), a high-resistance resistor wire (12) which is connected in parallel with a fusible wire of the protective device, and a holder which absorbs the prestress of the spring (16). The holder contains a section of the high-resistance resistor wire (12) which is in the form of a winding (18) and is passed at least once around the moveable end of the spring (16) in order to form the prestress, and which is at least partially in thermally conductive contact with the material of the activator (20). Above a limit temperature, the activator (20) lifts, for example by destruction of the winding (18) or by melting through, the holder and activates the impact signaling system (9) by reducing the load on the spring (16).

Abstract: Bulk-modified potting composition based on a curable epoxy resin or on a mixture of these resins, where the resin or the mixture is composed of an epoxy resin, a hardener, where appropriate an accelerator, and also other additives, such as fillers, flexibilizers, and colorants, which potting composition (a) comprises a three-dimensionally crosslinked polysiloxane in disperse form and with a particle size in the range from 0.02 &mgr;m to 50 &mgr;m, which, where appropriate, has reactive groups which can react chemically with the epoxy resin and/or the hardener, (b) a selected linear or branched siloxane compound which has reactive groups which can react chemically with the epoxy resin and/or the hardener; and also, where appropriate, (c) a low-molecular-weight oligomeric siloxane compound, the use of the potting composition as an engineering material or as an insulating material, and the moldings and insulation produced therefrom.

Abstract: Mold-release agent for producing thermoset moldings with a hydrophobicized surface, where the agent comproses (I) at least one compound with mold-release action, and also (ii) at least one reactive, where appropriate hydrolyzable, silane compound, which is capable of reacting chemically in situ with the thermoset surface which forms during the molding process. The use of a mold-release agent of this type in a molding process and/or in a post-curing process for the production of thermoset moldings with a hydrophobicized surface, and also the moldings produced in this way.

Abstract: A fuse has a fuse element (6) with a fusible conductor (7) of a conductor material (8) such as Ag, Cu or Al and is provided with doping points (9) following one another at regular intervals. There, the conductor material (8) has a directly adjoining layer of a first compound (10) of the same with a doping material such as In or Ge. It forms mixed crystals which contain the conductor material (8) and the doping material in a fixed stoichiometric ratio, such as for example Ag2In, and is separated from said conductor material by a stable phase boundary. The doping points (9) weaken the fusible conductor by lowering the melting point to below 250° C., so that arc formation rapidly occurs there when there are short-circuit currents, although its electrical resistance per unit of length is under some circumstances only a few percent greater than in the remaining region. The fusible conductor (7) bears a continuous layer of a burn-up material (12).

Abstract: In a fuse chamber (8) there is arranged as a quenching gas source a burn-off element (11), which concentrically surrounds an arc chamber (10) and is separated from it by a fuse element (9), which consists of metal foil, preferably silver foil, and the outer side of which is adjoined by the burn-off element (11). The latter consists of an igniting material (12), arranged in the form of a ring running around centrally, and a gas-evolving material (13). Both materials consist, for example, of guanidine or guanidine derivatives as the combustible material and an oxidant, the proportion of which in the igniting material (12) is hyperstoichiometric. The arc chamber (10) is bounded at opposite ends by nozzles (7a,b), which connect it to exhaust volumes (4a,b). When there is an overcurrent, the fuse element (9) heats up to the igniting temperature of the igniting material (12) and is torn open centrally.