JP4371973B2 - Conductive bushing - Google Patents

Description

  The present invention relates to a conductive rod bushing having a center clamp structure in which a rod exposed to the outdoors is a conductive rod among the bushings used for insulating and supporting a high-voltage power line and the like.

  A bushing that insulates and supports high-voltage power lines, etc. is provided with a porcelain steel pipe between the ground-side metal fitting and the high-voltage metal fitting. It has a structure that is sealed to ensure insulation. In order to prevent leakage of these insulating gases and insulating oils, gaskets are provided on both upper and lower end surfaces of the soot tube. These gaskets are housed in a compressed state inside the gasket groove, and exhibit a sealing function by a reaction force generated by being crushed. However, during many years of use, the gasket may deteriorate and lose reaction force, and the sealing function may deteriorate and lead to oil leakage.

  Therefore, instead of the reaction force of the gasket itself, the gasket interposed between the upper end surface of the soot pipe and the high-pressure side metal fitting and between the lower end surface of the soot pipe and the ground side metal fitting is compressed by the tension of the center pipe to seal it. A bushing having a center clamp structure to be performed (Patent Document 1) has been developed. In this center clamp type bushing, tension is always applied to the center pipe by the spring built in the high-pressure side metal fitting, and the compression force, which is the reaction force, acts on the high-pressure side metal fitting, vertical pipe, and grounding side metal fitting. At the same time, the gasket is compressed. Since the gasket is compressed by the spring in this way, there is an advantage that the sealing function of the gasket is not impaired even when used for many years.

  On the other hand, a bushing has been developed in which a soot pipe exposed to the outdoor side is a conductive soot pipe. The conductive soot tube is a soot tube made of porcelain soot with a conductive glaze surface. It exhibits excellent antifouling performance due to the heat generation effect caused by the weak current flowing in the glaze layer and the uniform voltage distribution effect. The generation of corona can be prevented. For this reason, if it uses for the bushing installed in a pollution environment, there exists an advantage which can improve antifouling performance.

  However, when a conductive soot pipe is used for the bushing of the center clamp structure, a gasket is interposed between the high-voltage side metal fitting and the soot pipe, and between the ground side metal fitting and the soot pipe. However, the above weak current does not flow through the glaze layer, and the desired antifouling performance cannot be obtained. Therefore, as shown in Patent Document 2, a ring-shaped elastic clamp fitting is fitted on the outer periphery of the end of the conductive soot tube, and the ring-shaped elastic clamp fitting and the ground-side fitting are electrically connected by a bond line. Has been developed. Although it was thought that this could avoid the above-mentioned problem, subsequent studies have revealed that there are two problems with the conductive bushing having the structure of Patent Document 2.

  First, the ring-shaped elastic clamp fitting is in close contact with the glaze surface of the conductive bushing due to the elastic force, but the contact resistance increases to several tens to several hundreds of MΩ unless it is brought into close contact with a considerably strong pressure. The meaning of using bushing is lost. That is, the conductive soot tube exhibits excellent antifouling performance when the overall resistance value is set to 30 to 60 MΩ, and the contact resistance between the ring-shaped elastic clamp fitting and the glaze surface is several tens to several hundreds. When it becomes MΩ, there is no meaning using a conductive bushing. Even if appropriate conduction is obtained at the beginning, the contact resistance may increase if the elasticity of the ring-shaped elastic clamp fitting deteriorates during long-term use.

Secondly, electrical equipment using a bushing, such as a transformer, is periodically inspected for deterioration of insulation. However, in the conductive bushing having the structure of Patent Document 2, there is electrical conduction between the high-voltage side metal fitting and the ground-side metal fitting. Since it is connected by a soot tube, it is impossible to measure the insulation resistance and dielectric loss tangent between the high-voltage side metal fitting and the ground-side metal fitting, which is an indicator of the insulation deterioration state as it is. Therefore, in the periodic inspection, it is necessary to cut the bond line or remove the ring-shaped elastic clamp fitting, which increases the number of work steps.
Japanese Patent Publication No. 8-3969 Japanese Patent Laid-Open No. 11-144541

  The present invention solves the above-mentioned conventional problems, and the anti-fouling performance of the conductive rod bushing by electrically connecting the glaze surface of the conductive rod tube and the high-voltage side metal fitting and the ground side metal fitting with stable contact resistance. The present invention has been made in order to provide a conductive bushing having a center clamp structure that can sufficiently exhibit the above-described characteristics and can easily check the insulation deterioration state of an electrical device using the bushing.

In order to solve the above-mentioned problems, the present invention uses an outdoor side pipe as a conductive pipe, and has gaskets interposed between the upper end surface and the high-voltage side metal fitting and between the lower end surface and the ground side metal fitting, respectively. a is allowed to guide Den釉bushing center clamp structure compressed by the tension of the central pipe, the upper and lower end portions in the conductive metal conductively bonded and fixed by the respective conductive cement or conductive resin of the conductive釉碍tube, each conductive metal Screw holes are also formed on the outer peripheral surface of the metal plate, and screw holes are also formed on the high-voltage side metal fitting and the ground-side metal fitting, respectively. Bolts are tightened to the holes, and both ends of the lower flexible conductor are bolted to the screw holes of the lower conductive bracket and the screw holes of the ground bracket. Between the brackets Respectively it is characterized in that the electrically connected.

In the conductive bushing of the present invention, the conductive metal fittings are conductively bonded and fixed to the upper and lower ends of the conductive metal pipe with conductive cement or conductive resin , respectively, and between each conductive metal fitting, the high voltage side metal fitting and the ground side metal fitting. Because it is electrically connected by a flexible conductor, unlike the conventional structure using a ring-shaped elastic clamp metal fitting, it electrically connects between the high-voltage side metal fitting, the conductive metal pipe, and the earth-side metal fitting with a stable contact resistance. be able to. In particular, when conductive cement bonding is performed, low contact resistance can be maintained over a long period of time. For this reason, the inherent antifouling performance of the conductive bushings can be sufficiently exhibited.

In the conductive bushing of the present invention, each conductive metal fitting is electrically connected between the high-voltage side metal fitting and the ground-side metal fitting by a flexible conductor having a bolt-clamping end , so that the bolt is not used for periodic inspection. The upper and lower flexible conductors can be easily removed by a method such as loosening. As a result, both the insulation resistance and the dielectric loss tangent between the high-voltage side metal fitting and the ground-side metal fitting can be measured without being affected by the resistance value of the conductive bushing.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 is a cross-sectional view showing an embodiment in which the present invention is applied to an oil-filled bushing, wherein 1 is a ground-side metal fitting provided with a flange 2 for mounting to an electric device such as a transformer, and 3 is exposed to the outdoor side. The conductive soot pipe 4 is a soot pipe inside the apparatus. The conductive soot tube 3 is obtained by applying a conductive glaze to the surface of a porcelain soot body and improving the antifouling performance. Reference numeral 5 denotes a high voltage side metal fitting on the bushing head side, and reference numeral 6 denotes a high voltage side metal fitting on the inside of the apparatus. The high pressure side metal fitting 5 on the head side forms an expansion chamber for insulating oil.

  Gaskets 7 are interposed between the upper end surface of the conductive metal tube 3 and the high-voltage side metal fitting 5, and between the lower end surface of the conductive metal tube 3 and the ground-side metal material 1, respectively. Gaskets 8 are also interposed between the high-pressure side metal fitting 6 and between the upper end surface of the soot tube 4 and the ground-side metal fitting 1. These gaskets 7 and 8 are compressed by the center clamp force described below, and are sealed so that the insulating oil sealed inside the bushing does not leak.

  Reference numeral 9 denotes a center pipe disposed between the high-pressure metal fittings 5 and 6. An electric field relaxation capacitor 10 composed of an electrode layer and an insulating layer is formed on the outer periphery of the center pipe 9, and a lead lead 11 passes through the center pipe 9 in order to allow current to flow. The lower end portion of the center pipe 9 is screwed and fixed to the high-pressure side metal fitting 6 inside the apparatus, but the upper end portion is fixed to the spring receiver 12 inside the high-pressure side metal fitting 5 on the head side by a nut 13. A compression spring 15 is installed between the spring receiver 12 and the spring receiver 14 on the inner bottom surface of the high-pressure side metal fitting 6, and always applies tension to the center pipe 9. As a result, a center clamping force acts on the entire bushing, and the surface pressure of the gaskets 7 and 8 is not lost even if used for many years.

  In such a bushing with a center clamp structure, the high-voltage side metal fitting 5, the conductive metal tube 3 and the ground-side metal material 1 are insulated by the gasket 7, and a weak current is passed through the glaze surface of the conductive metal tube 3. I can't. Therefore, in the present invention, the conductive metal fittings 16 and 17 are conductively bonded and fixed to the upper and lower ends of the conductive rod tube 3, respectively. The conductive fittings 16 and 17 are preferably metal rings, and are bonded to the conductive casing 3 before assembling the bushing.

  As the adhesive 18 of the conductive metal fittings 16 and 17, a conductive adhesive is used, and it is particularly preferable to use a conductive cement that can maintain a stable contact resistance over a long period of time. The conductive cement can maintain a good contact resistance with the conductive rod even in a dry state. The long-term reliability of good contact resistance with cement has been proven since there was no problem in the past 10 years of application to suspension systems. However, if a conductive resin is used, substantially the same effect can be obtained by resin bonding.

The conductive metal fitting 16 and the high voltage side metal fitting 5 are electrically connected by a flexible conductor 19 having a removable end. In this embodiment, an end portion of a bolt fastening mold is adopted as the removable end portion. Similarly, the conductive metal member 17 and the ground side metal member 1 are also electrically connected by a flexible conductor 20 having a bolted end. Screw holes are formed in the outer peripheral surfaces of the conductive metal fittings 16 and 17, and ends of the flexible conductors 19 and 20 are fixed by bolts. Screw holes are also formed in the upper surface of the high-voltage side metal fitting 5 and the side surface of the ground-side metal fitting 1, and the other ends of the flexible conductors 19 and 20 are fixed by bolts. If the lower end of the flexible conductor 20 is bolted to the side surface of the ground side metal fitting 1 in this way, it is not necessary to increase the size of the ground side metal fitting 1 and the conventional ground side metal fitting 1 can be used. it can.

  The conductive bushing of the present invention configured as described above has a center clamp structure in which insulating gaskets 7 are interposed on the upper and lower sides of the conductive rod 3, and the high-voltage side metal fitting 5 and the glaze surface of the conductive rod 3 The ground side metal fitting 1 is electrically connected through the flexible conductor 19 or 20 and the conductive metal fitting 16 or 17. For this reason, in a use state in which a high voltage current is passed through the lead-in lead 11, a weak current flows on the glaze surface of the conductive casing 3, and excellent antifouling performance due to the heat generation effect by the weak current and the uniform effect of voltage distribution And the generation of fouling corona can be prevented. For this reason, it is suitable for installation in a fouling environment.

Further, when carrying out a periodic inspection of an electrical device incorporating the conductive bushing of the present invention, the bolts are loosened as shown in FIG. 2 and the ends of the flexible conductors 19 and 20 are separated from the conductive fittings 16 and 17. To do. As a result, since the high voltage side metal fitting 5 and the ground side metal fitting 1 are insulated without being affected by the conductive flaw, the insulation resistance and dielectric loss tangent between the high voltage side metal fitting 5 and the ground side metal fitting 1 are accurately determined. It becomes possible to measure. As described above, the conductive scissors bushing according to the present invention can easily remove the flexible conductors 19 and 20 by hand, so that it is possible to easily and accurately check the insulation deterioration state of the electrical equipment.

  As described above, the conductive bushing of the present invention employs a center clamp structure to maintain the surface pressure of the gaskets 7 and 8, while the glaze surface of the conductive rod tube, the high-pressure side metal fitting 5 and the ground side. The metal fitting 1 can be electrically connected with a stable contact resistance, and the antifouling performance of the conductive iron bushing can be sufficiently exhibited. Moreover, since the flexible conductors 19 and 20 can be removed manually, it is possible to easily check the insulation deterioration state of the electrical equipment using the bushing. Furthermore, there are many advantages such as no need to change the basic structure of the bushing itself, and no need to increase the size of the grounding metal fitting 1.

It is a center longitudinal cross-sectional view which shows embodiment of this invention. It is a center longitudinal cross-sectional view which shows the state at the time of an inspection.

DESCRIPTION OF SYMBOLS 1 Grounding side metal fitting 2 Mounting flange 3 Conductive soot pipe 4 Equipment inside side soot 5 Head side high voltage side metal fitting 6 Equipment inside high voltage side metal fitting 7 Gasket 8 Gasket 9 Center pipe 10 Capacitor 11 Pull-in lead 12 Spring receiver 13 Nut 14 Spring receiver 15 Compression spring 16 Conductive fitting 17 Conductive fitting 18 Adhesive 19 Flexible conductor 20 Flexible conductor

Claims (1)

Conduction of center clamp structure where the outdoor side pipe is made of conductive pipe, and gaskets are interposed between the upper end surface and the high voltage side metal fitting and between the lower end surface and the ground side metal fitting, respectively, and compressed by the tension of the center pipe. It is a bushing, and conductive metal fittings are conductively bonded and fixed to the upper and lower ends of the conductive metal pipe with conductive cement or conductive resin , screw holes are formed on the outer peripheral surface of each conductive metal fitting, and high voltage side metal fittings Screw holes are also formed in the metal fitting on the ground side and the ground side metal fittings, and both ends of the upper flexible conductor are bolted to the screw holes on the upper electric conduction metal fitting and the screw holes on the high voltage metal fitting. By bolting both ends of the screw to the screw hole of the lower conductive metal fitting and the screw hole of the ground metal fitting, each conductive metal fitting, the high voltage metal fitting, and the ground metal fitting are electrically connected. Characteristic conductivity Bushing.

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