JPH08223770A - Air termination joint box for power cable - Google Patents

Abstract

PURPOSE: To protect a cable core in an insulator against buckling while ensuring an oil gap between the cable core and a capacitor cone by disposing a spacer in the oil gap such that convection of insulation oil is not impeded. CONSTITUTION: A spacer 10 is disposed inside a joint between a capacitor cone 3 and a metal pipe 4. A ring spacer 10 having a slit 18 in the inner circumferential face thereof is employed. Since the slit 18 serves as an oil channel, convection and circulation of insulation oil 7 is not impeded. With such structure, a cable core 1 in an insulator 2 can be protected against buckling while ensuring an oil gap 8 between the cable core 1 and the capacitor cone 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an air termination junction box for power cables. In particular, the present invention relates to a technique for reducing the temperature rise of an air termination junction box, which is lengthened in response to an increase in ultrahigh pressure.

[0002]

2. Description of the Related Art As an internal insulation method for an air termination junction box for an ultra-high voltage power cable, a condenser cone type is generally used in which a thin metal foil is concentrically inserted into a reinforced insulator. In the conventional type, the condenser cone is adhered onto the cable core via a reinforcing insulating oil-impregnated paper. However, when the current capacity is large, such as for large-sized cables, it is necessary to reduce the temperature rise in the air termination connection warehouse, and for that reason, an oil gap of about 10 mm is provided between the cable core and the condenser cone. As the insulating oil circulation cooling type, the insulating oil warmed by the heat generated from the cable conductor is radiatively cooled while raising the oil gap and lowering the inner surface of the porcelain tube. I was there. This one is actually
See Japanese Patent No. 17498, for reference.

[0003]

By the way, the rush output 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 air termination junction box. In addition, in a normal type air termination 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 through the reinforcing insulating oil-impregnated paper, so the bending rigidity of the entire cable Is large and does not cause a problem due to the bending or buckling of the cable core in the air termination junction box, but for ultra-high voltage cables installed in heavily polluted areas, of course, the porcelain tube length becomes longer and as a measure to reduce the temperature rise. In the case of an insulating oil circulation cooling type with an oil gap provided between the cable core and the condenser cone, there is a concern that the cable core may bend or buckle in the oil gap due to thermal expansion and contraction of the cable core in the porcelain tube. was there.

Therefore, an object of the present invention is to provide an aerial termination connection box for power cables, which can prevent buckling of the cable core in the porcelain tube while ensuring an oil gap between the cable core and the condenser cone. To provide.

[0005]

The air termination junction box for electric power cables of the present invention, which has been made to achieve the above object, is a cable core and a condenser cone provided in an insulator tube filled with insulating oil. In an air-termination box for power cables, which has an oil gap that allows convection of insulating oil between the capacitor cone and the cable core, a spacer is used to prevent convection of insulating oil. By interposing so as not to exist, convection of insulating oil and prevention of buckling of the cable core are both achieved.

Such a spacer is preferably arranged between the metal pipe extending from the upper part of the condenser cone and the cable core. This is because the reinforcing oil-impregnated paper is wrapped around the cable core on the lower side of the condenser cone to control the electric field in the longitudinal direction, so the bending rigidity of that portion is large and buckling does not easily occur, but on the other hand, the condenser cone The upper part of the inside is inside the metal pipe (aluminum pipe) that electrically connects the conductor drawing rod and the metal foil of the condenser cone. Especially, in the case of long porcelain insulation pipe, the metal pipe becomes longer, so the cable core at that part This is to prevent the buckling of. Spacers may be provided at regular intervals, for example, at intervals of 1 to 2 m.

Further referring 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: circular constant). Here, EI is the flexural 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 can be prevented by reducing the length (L) between the cable core supporting points. Since the EI is large in the part where the reinforcing insulating paper is wrapped around the cable core and the capacitor cone, it can be considered that buckling does not occur. Therefore, a spacer is provided at the upper part of the exposed state of the cable core and the capacitor cone or the tip of By integrating with the attached metal pipe, the buckling of the cable core was prevented.

A preferred embodiment of the spacer is a ring-shaped molding made of aluminum or a plastic material, and the inner peripheral surface of which is slit so that an oil passage can be formed.

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

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a preferred embodiment of an air termination junction box for electric power cables according to the present invention, and FIG.

In the figure, 1 is a cable core exposed by stripping, 2 is a porcelain tube, 3 is a condenser cone, 4 is a metal pipe (aluminum pipe), 5 is a conductor drawing rod, 6 is reinforced insulating paper, and 7 is insulating. Oil, 8 is an oil gap, 9 is an epoxy bell mouth, and 10 is a spacer. Then, cable core 1
A conductor lead-out rod 5 is connected by compression to the cable conductor 14 exposed at the tip of the conductor, and the conductor lead-out rod 5 is fixed in a penetrating state to the porcelain insulator 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 attached thereon.

An oil gap 8 is provided between the cable core 1 and the condenser cone 3. The insulating oil 7 heated by the heat generated by the cable rises in the oil gap 8 and rises to the insulator 2
It is more naturally convected by descending the inner surface of the and cooled by circulation.

The lower part of the condenser cone 7 is the mounting plate 1.
A bolt or the like is attached to 1. A metal pipe (aluminum pipe) 4 is attached to the upper part of the condenser cone 3, and its extension end, that is, the upper end, is the adapter 1.
It is in contact with the conductor extraction rod 5 via 7.

In this embodiment, a spacer 10 is provided inside the connecting portion between the condenser cone 3 and the metal pipe (aluminum pipe) 4. As shown clearly in FIG. 2, the spacer 10 has a ring shape and is provided with a slit processing groove 18 on the inner peripheral surface thereof, and the slit processing groove 18 serves as an oil passage for convection of insulating oil; Is done.

The air termination junction box of the present embodiment is applied to a 500,000 V DC OF cable using an 8 m porcelain tube grounded in a heavily polluted area, and an aluminum pipe is used as the metal pipe 4 and its length is about 4 m. In this case, as a result of attaching the spacer of the present invention, the buckling prevention of the cable core could be reliably achieved.

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

The form of the spacer need not be limited to the above embodiment and various forms are conceivable. It is also possible, for example, to insert several hollow metal or plastic pipes inside the condenser cone or its upper metal pipe. Further, a method of binding several thin plastic rods or wires vertically on the cable core, or winding them in a coin spring shape on the cable core is also conceivable.

The spacer is made of an insulating material, for example, an insulating plastic or a material having insulating paper as a base material, if it is used in a portion requiring electrical insulation.

[0020]

As described above, according to the air termination junction box for a power cable of the present invention, the seat of the cable core in the porcelain tube is ensured in a state where the oil gap between the cable core and the condenser cone is surely secured. It is possible to achieve the intended purpose of providing an air termination junction box for a power cable capable of preventing bending, and it can be said that the practical effect is great.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view of the main part of an air termination junction box for a power cable in an embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a main part of a power cable air termination junction box according to another embodiment of the present invention.

[Explanation of symbols]

 1 Cable Core 2 Insulator Tube 3 Condenser Cone 4, 4a, 4b Metal Pipe (Aluminum Pipe) 5 Conductor Drawbar 6 Reinforced Insulating Paper 7 Insulating Oil 8 Oil Gap 9 Epoxy Bell Mouth 10 Spacer 11 Mounting Plate 12 Lower Copper Tube 13 Oiltight Seal 14 cable conductor 15 upper bracket 16 cable metal sheath 17 adapter 18 slit groove

Front page continuation (72) Inventor Ryuji Miyato 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. (72) Inventor Kazuki Terajima 6-15-1, Ginza, Chuo-ku, Tokyo (72) Inventor Kenji Nakayama 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Hidaka Factory (72) Inventor Sumio Koibuchi 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Cable Co., Ltd. Hidaka factory

Claims (3)

[Claims] 1. An air-termination terminal box for a power cable, comprising an oil gap for allowing convection of insulating oil between a condenser core and a cable core provided in a porcelain insulator tube filled with insulating oil. An air termination junction box for a power cable, characterized in that a spacer is interposed in an oil gap between the condenser cone and the cable core so as not to prevent convection of insulating oil. 2. A spacer is disposed between the metal pipe extending from the upper part of the condenser cone and the cable core,
An air termination junction box for a power cable according to claim 1. 3. The air termination junction box for a power cable according to claim 1 or 2, wherein the spacer is formed of aluminum or a plastic material in a ring shape, and has an inner peripheral surface slitted so as to serve as an oil passage. .