JPH0541341U - Electrical stress relief device for power cable - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to easily manufacture a stress cone used for a terminal portion or a connection portion of a power cable with a low failure rate, and to eliminate the need to press the stress cone on a reinforcing insulator. You can [Structure] The stress cone 34 comprises a stress cone molded body 32 that is radially compressed and attached between the outer conductor 16 of the power cable 12 and the reinforcing insulating body 36. Power cable 1
It has a cone extension 32a extending in the space between the second outer conductor 16 and the reinforced insulator 36. Further, the stress cone electrode 30 and the electric field suppressing portion 30a are formed from the conductive layer 31 formed continuously from the surface of the stress cone molded body 32 that contacts the outer conductor 16 of the power cable 12 along the surface of the cone extension portion 32a. Made of The stress cone electrode 30 and the electric field suppressing portion 30a are formed by a simple means such as surface coating or vapor deposition.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an improvement in an electrical stress relieving device for a power cable used in, for example, a terminal portion or a connecting portion of a power cable.

[0002]

[Prior Art]

 Generally, as shown in FIG. 3, this type of electrical stress relieving device has a stress cone 34 having a stress cone electrode 30 which is provided, for example, in the terminal portion 20 of the electric cable 12 and is in close contact with the outer conductor 16 of the power cable 12. And a reinforcing insulator 36 that receives the stress cone 34. The stress cone electrode 30 has an electric field suppressing portion 30a that is provided on the stress cone 34 and integrally extends from the stress cone electrode 30. Has an auxiliary electrode 42 provided so as to cooperate with the electric field suppressing section 30a.

The prior art electrical stress relieving device comprises spring pressing means 60 for pressing the stress cone 34 between the insulating layer 18 of the power cable 12 and the reinforcing insulation 36. The stress cone electrode 30 is formed of a conductive rubber exposed on the inner peripheral surface of the stress cone 34 so as to be in close contact with the outer conductor 16 of the power cable 12, and the electric field suppressing portion 30a is formed of a reinforcing insulator. It is molded from a conductive rubber which extends integrally from the stress cone electrode 30 into the stress cone 34 so as to come close to the auxiliary electrode 42 inside. The spring pressing means 60 is composed of a coil spring 66 held by a plurality of spring holding rods 64 fixed to a stress cone pressure contact member 62, and the coil spring 66 is attached to a supporting rod 68 screwed into the reinforcing insulator 36. The stress cone 34 is pressed by the attached washer 70 and pressed to the right in FIG. 3, and is pushed into the tapered space between the insulating layer 18 and the reinforcing insulating body 36 of the power cable 12. In FIG. 3, reference numeral 22 is an insulator tube, 24 is a support insulator, 38 is a metal reinforcing portion of the reinforcing insulator 36, 44 is seal packing, 46 is a set screw for fixing the metal reinforcing portion 38 to the support insulator 24, and 56 is It is a space within the terminal unit 20.

[0004]

[Problems to be solved by the device]

 However, in the electrical stress relieving device for a power cable according to this conventional technique, the stress cone 34 includes stress cone molded bodies 32A and 32B molded from insulating rubber, a stress cone electrode 30 molded from conductive rubber, and an electric field suppressing section. Since the electric field suppressing portion 30a is formed by being embedded between the stress cone molded bodies 32A and 32B, an insulating rubber and a conductive rubber are sequentially manually attached to a core metal having a predetermined diameter. Since the stress cone has to be placed in a mold and then vulcanized and molded after molding, the stress cone is difficult to manufacture, the manufacturing efficiency is poor, and the defect rate is high.

It is an object of the present invention to provide an electric stress relieving device for a power cable, which avoids the above-mentioned drawbacks and allows a stress cone to be easily manufactured with a low failure rate.

[0006]

[Means for Solving the Problems]

 The problem-solving means of the present invention consists of a stress cone having a stress cone electrode that is in close contact with the outer conductor of the power cable and a reinforcing insulator that receives this stress cone. In an electrical stress relieving device for a power cable that has an electric field suppressor that extends all over, a stress cone is installed by compressing it radially between the reinforcing insulator and the outer conductor of the power cable and reinforcing it with the insulating layer of the power cable. It consists of a stress cone molded body made of insulating rubber that has a cone extension that extends in the space between the insulator and the stress cone electrode and electric field suppressor are the outer conductor of the power cable of the stress cone molded body. It is characterized by a conductive layer formed along the surface of the cone extension from the surface in contact with To provide an electrical stress relieving device for a power cable.

[0007]

As described above, the stress cone has the cone extension portion extending in the space between the outer conductor of the power cable and the reinforcing insulator so as to be compressed and attached in the radial direction. If the electrode consists of a conductive layer formed along the surface of the cone extension from the surface of the outer conductor of the stress cone molded power cable, the stress cone can be easily manufactured by simple molding, Further, since no means for pressing the stress cone is required, the terminal portion or the connecting portion of the power cable can be downsized.

[0008]

【Example】

 1 and 2 show a terminal portion 20 of a power cable 12 equipped with a power cable electrical stress relieving device 10 according to the present invention. However, the present invention can be applied to not only the terminal portion of the power cable but also the connection portion as well.

At the end of the power cable 12, the sheath 14, the outer conductor 16 and the insulating layer 18 are sequentially stripped off to expose the conductor, the outer conductor 16 and the insulating layer 18 which are not shown in order. The conductor is compression-connected to a terminal conductor of an electric device to form a terminal portion 20, and the terminal portion 20 includes a porcelain insulator 22. 1 and 2, reference numeral 24 is a support insulator that insulates and supports the porcelain insulator 22, and reference numeral 26 is a protective metal fitting mounted across the power cable 12 and the terminal portion 20. The end portion of the protective metal fitting 26 on the electric power cable side is fixed to the sheath 14 of the electric power cable by an appropriate means, and a waterproof tape or the like is wound over the end portion of the protective metal fitting 26 and the sheath 14 for waterproofing. The layer 28 is formed.

As shown in detail in FIG. 2, the electrical stress relieving device 10 includes a stress cone 34 having a stress cone electrode 30 that is in close contact with the outer conductor 16 of the power cable 12, and a reinforcing insulator that receives the stress cone 34. It consists of 36 and. The reinforcing insulator 36 includes a metal reinforcing portion 38 having a tubular portion 38B extending in parallel to the axial direction from an inner edge of a donut-shaped annular metal plate 38A, and an epoxy resin so as to embed the tubular portion 38B of the metal reinforcing portion 38. The resin reinforcing portion 40 is formed into a tubular shape, and the inner end of the resin reinforcing portion 40 has a tapered portion 40a whose inner diameter is gradually reduced.

The stress cone electrode 30 has an electric field suppressing portion 30 a provided on the stress cone 34 and integrally extending from the stress cone electrode 30. The electric field suppressing section 30a has a function of being in close contact with the outer conductor 16 of the power cable 12 and guiding the electric field of the outer conductor 16 to the right in FIG. 2 to moderate the electric field strength appropriately.

The reinforcing insulator 36 has an auxiliary electrode 42 extending from the metal reinforcing portion 38 and embedded in the resin reinforcing portion 40 so as to cooperate with the electric field suppressing portion 30 a. The metal reinforcing portion 38 is fixed to the support insulator 24 by a set screw 46 so that the metal plate is closely attached to the insulator tube 22 via the seal packing 44. As shown in FIG. 1, the brim-shaped end portion 26a of the protective metal fitting 26 on the porcelain tube 22 side is fixed to the metal reinforcing portion 38 by a set screw 50 so as to be in close contact with the metal reinforcing portion 38 via a seal packing 48. Has been done.

The stress cone 34 is mounted between the reinforcing insulator 36 and the outer conductor 16 of the power cable 12 by being compressed in the radial direction, and is placed in the space between the outer conductor 16 of the power cable 12 and the reinforcing insulator 36. It is composed of a stress cone molded body 32 made of insulating rubber and having a cone extension portion 32a extending in the direction. The stress cone molded body 32 has a concave portion 30b into which an annular holder 54 fixed by a set screw 52 is inserted in the metal reinforcing portion 38 of the reinforcing insulator 36 and is displaced in the axial direction by the annular holder 54. It is held so that it will not come out. Therefore, the compressed portion of the stress cone 34 is formed so as to have a wall thickness larger than the distance between the outer conductor 16 of the power cable 12 and the inner peripheral surface of the reinforcing insulator 36. The stress cone 34 presses the stress cone electrode 30 against the outer conductor 16 of the power cable 12 by the elastic repulsive force of the compressed portion.

In addition, the stress cone electrode 30 and the electric field suppressing portion 30a are formed of a conductive layer formed along the surface of the cone extension portion 32a from the surface of the stress cone molded body 32 in contact with the outer conductor 16 of the power cable 12. Made up of 31. As can be seen from FIG. 2, the electric field suppressing portion 30a is folded back along the rounded portion at the tip from the surface of the cone extension portion 32a facing the insulating layer 18 of the power cable, and the auxiliary electrode 42 of the reinforcing insulator 36 is embedded therein. Extends to the surface facing the raised portion.

As described above, since the stress cone electrode 30 and the electric field suppressing portion 30 a are not embedded in the stress cone 34, the stress cone 34 is molded into the stress cone molded body 32, and then the stress cone molded body 32 is molded. The stress cone electrode 30 and the electric field suppressing portion 30a can be formed by applying a conductive coating material on the surface of or by depositing a conductive metal.

Insulating oil or insulating gas is filled in the space 56 surrounded by the porcelain insulator 22, the reinforcing insulator 36, the stress cone 34, and the like. Therefore, the electrical insulation performance of the terminal portion 20 of the power cable 12 can be sufficiently maintained.

[0017]

[Effect of the device]

 According to the present invention, as described above, the stress cone is provided between the outer conductor of the power cable and the reinforcing insulator by being compressed and installed in the radial direction so as to have a cone extension portion extending in both spaces. In addition, since the stress cone electrode and the electric field suppressing section are made of a conductive layer which is continuously formed from the surface of the outer conductor of the power cable of the stress cone molded body along the surface of the cone extension, The stress cone can be easily manufactured by simple molding, and the stress cone electrode can be easily formed by simple means such as surface coating or vapor deposition, thus making the stress cone highly accurate and efficient. It is well manufactured and the stress cone is installed by compressing it radially between the power cable and the reinforced insulation, compressing the stress cone previously required. Since the pressing means is not required, there is a practical benefits that it is possible to miniaturize the terminal unit or the connecting section of the power cable.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an upper half of a terminal portion of a power cable including an electrical stress relieving device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a main part of the electrical stress relieving device of the present invention.

FIG. 3 is a cross-sectional view showing, in an enlarged manner, a part of a conventional electrical stress relieving device for a power cable.

[Explanation of symbols]

 10 Electrical Cable Stress Relief Device 12 Power Cable 14 Sheath 16 Outer Conductor 18 Insulating Layer 20 Terminal Part 22 Insulator Tube 24 Support Insulator 30 Stress Cone Electrode 30a Electric Field Suppression Section 30b Recess 32 Stress Cone Molded Body 32a Cone Extension 34 Stress Cone 36 Reinforcing Insulator 38 Metal Reinforcing Part 40 Resin Reinforcing Part 40a Tapered Part 42 Auxiliary Electrode 44 Seal Packing 46 Set Screw 52 Set Screw 54 Annular Holder

Claims (1)

[Scope of utility model registration request] 1. A stress cone having a stress cone electrode that adheres to an outer conductor of a power cable, and a reinforcing insulator that receives the stress cone. The stress cone electrode is provided on the stress cone and is formed from the stress cone electrode. In an electric stress relieving device for a power cable having an electric field suppressing portion extending integrally, the stress cone is attached by being compressed in a radial direction between a cylindrical portion of the reinforcing insulator and an outer conductor of the power cable. The stress cone electrode and the electric field suppressing section are made of an insulating rubber stress cone molded body having a cone extension section extending in a space between the taper section of the insulator and the insulating layer of the power cable. From the surface of the stress cone molded body that contacts the outer conductor of the power cable to the surface of the cone extension An electric stress relieving device for a power cable, characterized by comprising a conductive layer formed along the electric line.