BUSHEAD AND BUSH-TYPE TRANSFORMER INSULATOR FOR MEDIUM VOLTAGE SWITCHING APPLIED IN METAL AND ISOLATED
IN THE AIR
FIELD OF THE INVENTION The invention relates to bushing supports and bushing current transformers for medium voltage switching devices, insulated to the air and metallicly encapsulated, which are each time arranged on a carrier sheet and with it are detachably attached . BACKGROUND OF THE INVENTION Bushing or bushing guides, and bushing transformers serve in the medium voltage switching apparatuses for the fabrication of an electrical connection, between the accumulation rails or in general between the cable connections. and the switching devices. With bushing current transformers, the individual phases of the medium voltage switching devices are monitored in addition to the current ratios. Both the bushing insulator, as well as the
bushing current transformer, are measured constructively in such a way that they correspond to the mechanical requirements, in view of their carrying capacity and also to the electrical requirements in view of their resistance to volt a e e. SUMMARY OF THE INVENTION The task proposed by the present invention consists in conceiving bushing supports and bushing current transformers for measuring voltages, for example in the range of up to 24 kV, without exceeding in an important way the volume constructive used up to the present for low voltages of such apparatuses. According to the invention, this is achieved by the following characteristics: 1.1 The bushing insulator or bushing and the bushing transformer each have a rectangular bushing opening displaced from the front side outwards, which has a rectangular stairway shape , 1.2 In the passage opening, or bushing, a transverse section provided with a cross section is connected transversely,
preferably rounded with a conductive contact that appears outwards on the upper side, 1.3 The conductive contact is electrically connected by means of a first conductor with a counter-contact, 1.4 The passage opening and the intake part, are constituent parts of a cast resin body,
1. The cast resin body has, in the area on the front side of the passage opening, an external control electrode cast in cast resin and U-shaped, 1.6 The cast resin body is cast in the boundary area between the opening of passage and the intake part, with an internal control electrode protecting the disc-shaped passage opening, which is cast in resin. The increase in the resistance to voltage for the bushing or bushing insulator and the step current transformer is favored, in addition to the staircase shape, of the opening of the bushing for the extension of the leakage path, still further by the existence of two control electrodes, the external U-shaped control electrode and the disk-shaped internal control electrode, the
which are arranged in the cast resin body and there, were fixedly cast. With the rectangular-shaped hub or passage opening that increases from the inside to the outside in the form of a ladder, a contact arm of rectangular shape is introduced which conducts a high voltage, which serves for the production of an electrical conductive connection with the contact in the bushing opening, the electrical resistance in the area of the air section and the cast resin wall is increased in such a way that the field strength in the area of this voltage measurement can no longer act in a damaging manner . This measurement is supported by a common work with the external U-shaped control electrode that is at ground potential, whereby the intensity of the electric field of the counter-contact charged to the voltage is reduced by means of the equipotentiality that it is formed with respect to the external control electrode. Since the external control electrode is arranged directly in the region of the front sheet plate, the usually negative influences that occur with respect to the sheet plates of cutting edges in the voltage transitions and also the partial discharges are also eliminated. strong inside the openings of the bushing or
He passed. With the disc-shaped internal control electrode, the electric field and the equipotential lines in the casting resin are influenced in such a way that the counter-contact acts in a correspondingly increased manner, owing to the reducible air distance for the step opening. The electric field lines of the counter-contact are distributed practically in a spherical way, by the internal control electrode in the form of a disc. According to an advantageous embodiment of the invention, the following characteristics are achieved: 2.1 The external control electrode can be connected in an electrically conductive manner on the one hand, with a connection that is at ground potential and 2.2 The connection to ground potential is arranged on the front side in the area of the carrier sheet. With this, in an advantageous manner, the connection of potential to ground from the outside is reachable at all times, without any additional assembly expense. According to another advantageous embodiment of the invention, the
following characteristics: 3.1 The intake part contains a current transformer core; 3.2 The current transformer core encloses the primary conductor centrally; 3.3 The primary conductor is so electrically connected to the conductive connection that at least one part of the remote current transformer core is protected from the primary conductor. With this constructive conformation of the primary conductor, the voltage resistance is further increased by the corresponding branch of the equipotential lines in the area of the current transformer core. Another advantageous embodiment of the invention is presented by the following characteristics: 4.1 The step transformer or bushing is realized as an annular core transformer and 4.2 The primary conductor is extended in such a way that the entire core
Current transformer is protected to the outside. The resistance to voltage is then increased for the ring core transformer. DESCRIPTION OF THE FIGURES The invention will be explained more clearly by means of two exemplary embodiments shown in the drawings, wherein FIGS. 1 and 2 represent a step or bushing current transformer and FIGS. 3 and 4 show a step insulator support each. in two technical aspects, from the side of the side view in a partial view and in plan view.
DESCRIPTION OF THE INVENTION Figure 1 shows an example of embodiment for the step current transformer DSW disposed on the carrier sheet TBL in a partial cut view, in such a way that the counter-contact GKT with its first conductor PLT can be appreciated. and the LTA conductive connection. Simultaneously, it is recognizable that the primary conductor PLT cast in resin is centrally surrounding the current transformer core S K cast in the
GHK resin body (figure 2) and belonging to the step current transformer DSW and that the junction of the conduit to the LTA conductor contact surrounds at least a partial zone of the current transformer core SK moved upwards from the primary conductor PLT moved towards back, an approximately equal distance. In the lower partial cut zone of the step current transformer DSW, it is recognizable in the region of the DFO passage opening especially the staircase arrangement thereof, to increase the length of the leakage current path. With the front sheet plate shown in the projection, FBP indicates that the step current transformer DSW is fixed in place in the medium voltage switching device by means of an unspecified slot. In addition, the external control electrode SEA is arranged in the area of the front plate FBP, which on the one hand is connected to the earth potential connection EPA, with the potential of the defined earth point. As already indicated, this reduces the intensity of the electric field in the opening of the
DFO step, starting from the active counter-contact GKT with a corresponding control of the equipotential lines, defined with respect to the external control electrode. With this, among other things, the processes of partial discharge and excess tension are prevented, especially in the area of the cutting edges of the front sheet. Figure 2 shows the step-current transformer in a plan view, from which the fixing in place of the cast resin body GHK, inside the front sheet plate FBP, of the voltage switching apparatus is especially evident. half. Likewise, in this figure, the arrangement of the support arm or insulator STA and, in particular, the round cross-sectional contour of the AFT connection part with the LTA conductive contact, which can be reached from the outside, can be recognized in particular. Figure 3 is an exemplary embodiment to appreciate the DFS pitch support with the cast resin body GHK, whose essential function consists only in the preparation of an electrical connection which can be fitted in
the conductive connection LTA by means of its DFO passage opening. A contact arm that has a high voltage potential must thus be safely free of excess voltage, in contact with the counter-contact, not shown, which is placed in the same position as the step current transformer , at the end of the DFO passage opening. The DFS insulation passage support also has a support arm STA for the comparative measurement of the carrier force in relation to the installation not shown, which is in conjunction with the LTA conductor contact. The passage support or DFS insulator is also detachably connected to the carrier sheet TBL. In the plan view depicted in FIG. 4, the preferred rounded cross-sectional contour of the AFT tap portion as well as the LTA conductor contact and the STA support or insulator arm, here disposed as FIG. an arm displaced.