JP3121515B2 - Air terminal connection box for power cable - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an aerial terminal junction box for a power cable. In particular, the present invention relates to a technique for reducing a rise in temperature of an aerial terminal connection box which becomes longer in response to an ultra-high pressure.

[0002]

2. Description of the Related Art As an internal insulation system of an aerial terminal connection box for an ultra-high-voltage power cable, a capacitor cone type in which a thin metal foil is concentrically inserted into a reinforcing insulator and used as a capacitor is generally used. In the case of the normal type, the condenser cone is tightly adhered on the cable core through the reinforced insulating oil immersion paper. However, when the current capacity is large, such as for large size cables, it is necessary to reduce the temperature rise in the aerial termination junction box , and therefore, an oil gap of about 10 mm is provided between the cable core and the condenser cone. The insulation oil circulating cooling type is provided, in which the insulation oil warmed by the heat generated from the cable conductor is radiated and cooled while raising the oil gap and lowering the inner surface of the insulator tube, thereby reducing the temperature rise. . This thing is
See, for example, Japanese Patent No. 17498.

[0003]

By the way, the projecting power from the cable side due to the thermal expansion and contraction of the cable has been absorbed by providing the R portion below the snake laying portion of the cable or the aerial terminal connection box. In addition, in the conventional air-terminated junction box, the clearance between the cable core and the condenser cone is small and the condenser cone and the cable core are in close contact with each other via the reinforced insulating oil immersion paper. It is not a problem due to bending or buckling of the cable core in the aerial termination junction box.However, for ultra high voltage cables installed in heavy pollution areas, the length of the insulator tube is naturally longer, and as a measure to reduce the temperature rise. In the case of the insulating oil circulation cooling type with an oil gap between the cable core and the condenser cone, there is a concern that the cable core may be bent or buckled in the oil gap due to the thermal expansion and contraction of the cable core in the insulator tube. was there.

Accordingly, an object of the present invention is to provide an aerial terminal connection box for a power cable which can prevent buckling of a cable core in an insulator tube by ensuring an oil gap between a cable core and a condenser cone. To provide.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, an aerial terminal connection box for a power cable according to the present invention comprises a cable core and a condenser cone provided in an insulator filled with insulating oil. In the aerial terminal junction box for power cables, which has an oil gap that allows the convection of the insulating oil, a spacer is placed in the oil gap between the condenser cone and the cable core to prevent the convection of the insulating oil. Therefore, the convection of the insulating oil and the prevention of the buckling of the cable core are compatible with each other.

The spacer is preferably disposed between a metal pipe extending from the upper part of the condenser cone and the cable core. This is because, on the lower side inside the condenser cone, reinforced oil immersion paper is wound on the cable core to control the electric field in the longitudinal direction, so the bending rigidity of that part is large and buckling does not easily occur, but on the other hand, the condenser cone The upper part is inside a metal pipe (aluminum pipe) that electrically connects the conductor drawing rod and the metal foil of the condenser cone. Especially in the case of a long trunk insulator, the metal pipe becomes longer, so the cable core at that part This is to prevent buckling. The spacers are preferably provided at regular intervals, for example, at intervals of 1 to 2 m.

[0007] Referring further to the buckling of the cable core, the buckling strength (Fc) of the cable core can be expressed by the following equation: Fc = π ² / L ² · EI (π: pi). Here, EI is the bending rigidity determined by the cable, and L is the length between the cable core support points.
Therefore, it is understood that the buckling of the cable core is prevented by reducing the length (L) between the cable core support points. Since the EI is large at the part where the reinforcing insulating paper is wound on the cable core and the condenser cone, buckling may not occur, and therefore, a spacer is provided at the upper part of the exposed cable core to provide a condenser cone or a tip. By integrating it with the attached metal pipe, buckling of the cable core was prevented.

In a preferred embodiment, the spacer is formed in a ring shape from aluminum or a plastic material, and has a slit formed on an inner peripheral surface thereof so as to be an oil passage.

When the power cable is for direct current, the electric field control shares the resistance. If the cable core is eccentric due to thermal expansion and contraction, the size of the oil gap changes, and the resistance changes, so the sharing voltage changes. Therefore, in this case,
The spacer between the cable core and the condenser cone also serves as a component holding the cable core at the center, and is advantageous in terms of improving insulation.

[0010]

FIG. 1 shows a preferred embodiment of an aerial terminal connection box for a power cable according to the present invention, and FIG. 2 shows a cross section of a main part thereof.

In the drawing, reference numeral 1 denotes a cable core exposed by being stripped off, 2 insulator tubes, 3 a condenser cone, 4 a metal pipe (aluminum pipe), 5 a conductor lead rod, 6 a reinforcing insulating paper, and 7 an insulation. 8 is an oil gap, 9 is an epoxy bell mouth, and 10 is a spacer. Then, cable core 1
A conductor extraction rod 5 is connected by compression to the cable conductor 14 exposed at the tip, and the conductor extraction rod 5 is fixed in a penetrating state to the insulator tube 2 with a metal fitting by an upper metal fitting 15.

A reinforcing insulating paper 6 is wound around the cable core 1, and an epoxy bell mouth 9 is mounted thereon.

An oil gap 8 is provided between the cable core 1 and the condenser cone 3. Condenser cone
3, a through hole 30 for an oil passage is provided.
You. The insulating oil 7 warmed by the heat generated by the cable rises in the oil gap 8 and descends down the inner surface of the insulator tube 2 so that it convects more naturally and is circulated and cooled.

The lower part of the condenser cone 3 is a mounting plate 1
It is attached by bolts or the like to 1. A metal pipe (aluminum pipe) 4 is attached to an upper part of the condenser cone 3, and an extension end, that is, an upper end thereof, is an adapter 1.
7 is in contact with the conductor pull-out bar 5.

In this embodiment, a spacer 10 is provided inside the connection between the condenser cone 3 and the metal pipe (aluminum pipe) 4. As shown in FIG. 2, the spacer 10 is formed in a ring shape and provided with a slit processing groove 18 on the inner peripheral surface. The slit processing groove 18 serves as an oil passage and does not hinder the convection and circulation of the insulating oil. It is like that.

In the aerial terminal connection box of this embodiment, the invention is applied to a 500,000 V DC OF cable using an 8 m insulator tube installed in a heavy pollution area, and an aluminum pipe is used as the metal pipe 4 and its length is about 4 m. In such a case, as a result of attaching the spacer of the present invention, prevention of buckling of the cable core could be surely achieved.

FIG. 3 shows an example in which a spacer 10 according to the present invention is provided at a joint of a metal pipe.
0, a projection 10a is provided on the outer periphery of the metal pipe 4a, and the projection 10a is sandwiched between seams of the metal pipes 4a, 4b.
4b is fixed by screwing together.

The mode of the spacer does not need to be limited to the above embodiment, and various types can be considered. For example, it is conceivable to insert several hollow metal pipes or plastic pipes inside the condenser cone or its upper metal pipe. It is also conceivable to bind several thin rods or wires made of plastic vertically along the cable core or to wind them around the cable core in the form of a coil spring.

If the spacer is used in a portion requiring electrical insulation, the spacer is made of an insulating material, for example, an insulating plastic, a material based on insulating paper, or the like.

[0020]

According to the above-described aerial terminal connection box for a power cable according to the present invention as described above, the seat of the cable core in the insulator tube is ensured while ensuring an oil gap between the cable core and the condenser cone. It is possible to achieve the intended object of providing an aerial terminal connection box for a power cable capable of preventing buckling, and it can be said that the practical effect is great.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view of an entire airborne termination box for a power cable according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of an aerial terminal connection box for a power cable according to an embodiment of the present invention.

FIG. 3 is a vertical sectional view of a main part of a power cable submerged connection box according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cable core 2 Insulator tube 3 Condenser cone 4, 4a, 4b Metal pipe (aluminum pipe) 5 Conductor lead-out rod 6 Reinforcement insulating paper 7 Insulating oil 8 Oil gap 9 Epoxy bell mouth 10 Spacer 11 Mounting plate 12 Lower copper pipe 13 Oil tight seal 14 Cable conductor 15 Upper bracket 16 Cable metal sheath 17 Adapter 18 Slit processing groove

Continued on the front page (72) Inventor Ryuji Miyafuji 3-2-2 Nakanoshima, Kita-ku, Osaka-shi, Osaka Inside Kansai Electric Power Co., Inc. (72) Inventor Kazuki Terashima 6-15-1, Ginza, Chuo-ku, Tokyo Power supply development Inside (72) Inventor Kenji Nakayama 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture Inside the Hidaka Plant, Hitachi Cable Corporation (72) Inventor Sumio Koibuchi 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture No. 1 Inside the Hidaka Plant of Hitachi Cable Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H02G 15/22

Claims (3)

(57) [Claims] (1) A casing is provided at an inner center of a porcelain tube filled with insulating oil.
Insert the bull core and further between the cable core and the insulator tube
To the cable core and insulator tube.
The insulation oil is arranged with a predetermined gap
When heated by the heat of the cable, the cable core and
The gap between the condenser cones and the condenser
Convection through the gap between
An aerial termination junction box for power cables configured in
A predetermined distance between the cable core and the condenser cone
Spacer is continuous in the length direction of the above cable core
With a secure passage, and pass through the passage
Flowing the above-mentioned insulating oil into the insulator tube of the insulating oil.
An aerial terminal connection box for a power cable, characterized in that it is configured to allow a convection of the air. 2. A cable from above the condenser cone.
Between the metal pipe extending to the end of the cable and the cable core.
2. The aerial terminal connection box for a power cable according to claim 1, wherein the spacer is arranged. Wherein said spacer is of aluminum or plastic material is molded in a ring shape, a on the inner peripheral surface
With several slits formed along its length , or
Is a few hollow metal pipes or plastic pies
Cable around the cable core and the length of the cable core.
Or several plastics
Place a thin rod or wire around the circumference of the cable core
And attached along the length of the cable core, or
A thin plastic rod or wire around the cable core.
It is one of those wound around in a coil spring shape ,
The underwater junction box for a power cable according to claim 1 or 2.