Groove thermometer for electrical machines

RST for the statement of the machines dominant temperatures electrical in the slots is well-known it to build into these special groove thermometers which essentially consist of a temperature sensor, which is embedded in an insulant. As such temperature sensors are thermocouples with one or more Lötste! len, resistance thermometers or temperature-dependent semiconductors usable. Since these groove thermometers are directly at the coil of the electrical machine arranged, a current crossing of the windings can occur into the temperature measuring circle in the trouble. Therefore were so far in each case in or several overvoltage safety devices necessary, which were arranged between the temperature sensor and the Ständereisen, which was relatively complex. Such overvoltage safety devices become redundant by the invention. With a groove thermometer for electrical machines with a temperature sensor embedded in an insulant the insulant of a currentbasic screen from a metal or a Meta is in accordance with the invention! alloy with reduced conductivity surround, which exhibits connection elements for a connection with a grounded machine part. A such screen prevents the crossing of rivers on the temperature sensor also in troubles, since it is not destroyed by the fault currents flowing then and these over the connection elements to grounded machine parts derives. To the temperature measuring circle and the indicating measuring instruments thus no tensions can be transferred, so that an endangerment of the operating personnel with security is avoided. A faulty measurement steps also in the Störungsfa! l not up. The groove thermometer trained in accordance with the invention has further the advantage that by the use of a metallic material with reduced conductivity only small Wirbelstromvertuste arises. In order to reduce these still further, it is advisable to preferably accommodate the groove thermometer in slots with reduced transverse field i.e. in slots, which are occupied with directors/conductors of different phases. By the screen of the groove thermometer this can be arranged also in any place within the groove, how it with advantage to the hottest Ste! le, i.e. e.g. in the center of the groove between the directors/conductors of a Zweischichtwicklung, is brought in. In order the training of closed Krelsstr'. it ömen around the Temperaturflähler to avoid, is appropriate it that the screen contains a gap running in longitudinal direction. The manufacturing of a such screen is simplified still thereby that it consists of two into one another decisive, u-shaped ones parts, which are against each other insulating. This results in very flat training of the shielded groove thermometer, whereby for its employment only little area is necessary. It is advisable further to provide also the screen with an outside insulating layer so that within the groove an isolation of the Ahschirmung is ensured against the Ständereisen and the lamination of the bundle of laminations is not bridged. In the following the invention is described still on the basis a remark example more near, which in the design schematically, partly cut, gesture of! is lt. The groove thermometer --1-- for electrical machines consists of a temperature sensor --2--, e.g. one with platinum wire moldings taped. This temperature sensor --2-- lies in an insulant --3-- embedded. As screen two u-shaped box parts serve --4 and 5-- out of a sheet metal of a Widerstandslegierung, e.g. from copper, manganese and aluminum with reduced conductivity, which possess a resistivity of approximated 0.5 2.mmZ/m. This reduced conductivity prevents larger eddy current formations in the magnetic FeId of the groove. In addition the special koustruktive training of this groove thermometer results in a very flat design, which takes only little area, so that it is suitable in particular for an arrangement between Oberund lower layer of the windings. To the education of the u-shaped box parts --4 and 5-- in addition used sheet metals are insulant-covered in not represented way. The screen is thus from the beginning surrounded with an outside isolation opposite the groove walls. The used design of two Abschirmungsteflen, those by longitudinal column --6-- from each other separated and thus against each other and within the groove in an isolated manner against the Ständereisen, thereby minimum losses are ensured in the magnetic transverse field of the groove. Furthermore are at each u-shaped Kastenteii --4 and/or 5-- flexible braids --7-- fastened, which preferably are because of the place of the withdrawal of the holding wires and outside of the groove are laterally led out directly and fastened to a grounded machine part. The production in accordance with the Er£mdung of trained, represented groove thermometer is simplified when using epoxy resin as Isollerstoff thereby that the two, the screen of forming u-shaped box parts --4 and 5-- as form for the casting resin to be used it can whereby the outside outlines of the groove thermometer are fixed. In accordance with the Erfindnng if trained groove thermometer is to be used with an electrical machine, their coil after inserting into the slots of the machine completely is only soaked, then it is advisable to make at the same time with this soaking the coil isolation also the gate of the temperature sensor between the screen parts. One knows from there the temperature sensor --2-- only with a beschleunigerhaltigen insulating tape umwickehä and then over it the screen parts apply and in an appropriate way specify, e.g. by an outside Umbandelung by insulating tape. This still dry, not groove thermometer filled with Isolierstof£ is then built together with the coil into the machine and is not soaked there together with this.