JPH08251799A - Power cable connection structure and lead method - Google Patents

Abstract

PURPOSE: To make it possible to take heat countermeasures for lead work by a relatively simple work by permitting the configuration of a cable insulating body using only semi-synthetic paper having high reliability. CONSTITUTION: This is a connecting construction for an OF cable 4 having an aluminum cover 2 made of an aluminum corrugated tube in which the aluminum cover 2 and a connection box 6 are sealed with lead work during cable connection. An air gap 10 is formed between the aluminum cover 2 and a cable core 8 by enlarging the diameter of the end portion 2a of the aluminum cover 2 at the connecting side, and an insulation sheet 14 is inserted to the gap 10 and inside of the portion 12 to be worked with lead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power cable connection structure and a lead processing method.

[0002]

2. Description of the Related Art Among electric power cables having a metal sheath in general, in connection with an OF cable in particular, a seal between the metal sheath and a connection box is treated by lead work. Recently, in consideration of workability, etc., lead-free seals have been developed, such as using rubber packing or molding and tightening a metal sheath, but lead work is advantageous in terms of workability and cost. , It is thought that lead seals will continue to be used in many cases.

Usually, in the lead work of the cable connection portion, the cable is locally heated. For example, in the lead work of an OF cable, when the insulator is made of kraft paper, the heat resistance of the insulator is high, and therefore it is not necessary to consider the heat during the lead work. However, in the case of semi-synthetic paper developed for the purpose of reducing dielectric loss (PPLP with a polypropylene sheet placed in the center and kraft paper attached to both sides is the mainstream: hereinafter referred to as all-semi-synthetic paper) In order to prevent elution of polypropylene and the like, it is necessary to suppress the maximum temperature during lead processing to about 130 ° C.

Therefore, in the conventional lead processing method, instead of PPLP in the outermost layer (outermost layer of the insulator) of the cable core, kraft paper as a lead-resistant material or semi-synthetic paper such as PML having excellent heat resistance is used. To prevent the heat of lead work.

[0005]

However, the above-mentioned conventional lead processing method has the following problems. That is, when kraft paper is wound as the lead-resistant material, the dielectric properties are slightly inferior to those of the all-semi-synthetic paper cable. On the other hand, when the PML is wound, the reliability is low because the PML has not been used as a semi-synthetic insulating paper on an actual line.

The present invention has been made in view of the above-mentioned problems of the prior art. The cable insulator can be made of highly reliable all-semi-synthetic paper, and it is a relatively simple work to take measures against lead heat. It is an object of the present invention to provide a power cable connection structure and a lead processing method capable of performing the above.

[0007]

The present invention has the following configuration to achieve the above object. That is, the invention of claim 1 is a connection structure of a power cable having a metal sheath, wherein the metal sheath and the connection box are sealed by lead work at the time of connecting the cable, wherein the metal sheath and the cable core are A space is formed between the metal sheath by expanding the connecting side end of the metal sheath, and a heat insulating layer is inserted inside the space and inside the leaded portion. Is a connection structure of.

According to a second aspect of the present invention, in a lead working method for sealing the metal sheath and the connection box at the time of connecting an electric power cable having a metal sheath, the connection side end of the metal sheath is expanded to have a diameter larger than that of the metal sheath. An electric power characterized by forming a space between the sheath and the cable core, inserting a heat insulating layer into the space, and performing lead work on the metal sheath and the connection box outside the heat insulating layer in the cable radial direction. This is a cable lead method.

According to a third aspect of the present invention, there is provided a method of lead work for a power cable according to the second aspect, wherein an aluminum corrugated pipe is used for the metal sheath.

[0010]

According to the first and second aspects of the present invention, when the metal sheath and the connection box are sealed by lead work, a heat insulating layer (heat insulating material) is provided inside the lead work part and outside the cable core. ) Ensures that the cable insulation is protected from lead heat. Therefore, it is not necessary to wrap kraft paper, PML, or the like on the outermost layer of the cable core as in the conventional case. Therefore, it becomes possible to form the cable insulator with the highly reliable all-semi-synthetic paper that should be originally provided.

Further, since the measure against heat according to the present invention is only required to expand the diameter of the connection side end portion of the metal sheath and insert the heat insulating layer into the void formed by this, work using a relatively simple tool. At the same time, on-site construction is also possible.

According to claim 3, when the metal sheath is an aluminum corrugated tube, for example, the corrugated tube is stretched in the longitudinal direction of the cable before cutting so that the corrugated shape is formed into a substantially cylindrical shape, whereby the gap is formed. Since it can be easily secured, the diameter expansion work of the sheath can be easily performed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. First, the first embodiment will be described. Figure 1 shows the first
It is a fragmentary sectional view showing the cable connection structure of an example. FIG. 2 is a side view of the cable showing a state in which the aluminum cover is stretched in the first embodiment. FIG. 3 is a partial cross-sectional view of the cable showing a state in which the sheath diameter is expanded by inserting the device in the first embodiment.

In the first embodiment, as shown in FIG. 1, an aluminum sheath 2 made of an aluminum corrugated tube (an example of a metal sheath).
A connection structure of an OF cable (an example of an electric power cable) 4 having an aluminum cover 2 and a connection box 6 when connecting the cable.
In the case where and are sealed by lead work, between the aluminum sheath 2 and the cable core 8, a connection side end portion 2a of the aluminum sheath 2 is provided.
The void 10 is formed by expanding the diameter of the void 1.
A heat insulating sheet (corresponding to a heat insulating layer) 14 is inserted inside the 0 and inside the leaded portion 12. In addition,
This connection structure includes a sleeve 16 for connecting the conductor ends 4a, 4a of the two OF cables 4, 4 to be connected, and a reinforcing layer 18 provided around the conductor connection part. Further, the cable core 8 is a core of a normal OF cable in which an insulator is provided outside a cable conductor having an oil passage at the center.

Hereinafter, the lead working method in this embodiment will be described together with the configuration of each part. The aluminum cover 2 is corrugated into a sinusoidal waveform. In the present embodiment, as shown in FIG. 2, before cutting the aluminum sheath 2, both sides of the aluminum sheath 2 sandwiching the cutting line C are stretched in the cable longitudinal direction so that the aluminum sheath 2 and the cable core 8 are separated from each other. The space 10 is formed in the above.

That is, the dies 20, 20 fitted and locked to the outer surface of the aluminum cover 2 are disposed on both sides of the cutting line C in the cable longitudinal direction.
By separating 20 from each other by using air cylinders 22 and 22, for example, the corrugated aluminum cover 2 is moved to the die 2
It is formed into a substantially smooth cylindrical shape between 0 and 20, and its inner diameter is made larger than that of the corrugated shape. After that, when the aluminum sheath 2 is cut along the cutting line C, an open substantially cylindrical void 10 is formed between the vicinity of the cut end of the aluminum sheath 2 and the cable core 8.

When the size or shape of the void 10 is insufficient only by the method of stretching the aluminum cover 2, as shown in FIG. 3, the tip is formed in a taper shape and is larger than the inner diameter of the void 10. Device 24 with large outer diameter
The aluminum cover 2 can be further expanded in diameter by inserting through the opening of the void 10.

As shown in FIG. 1, the heat insulating sheet 14 has a substantially cylindrical shape that matches the shape of the void 10.
It is made of kraft paper, carbon paper, Teflon sheet or expanded Teflon sheet. The heat insulating sheet 14 is inserted into a space inside the void 10 facing at least the portion 12 to be lead-worked, after forming the void 10 by expanding the diameter of the aluminum cover 2.

In the lead work according to this embodiment, the heat insulating sheet 14 is inserted after the heat insulating sheet 14 is inserted, the conductors are connected, the reinforcing layer 18 is provided, and the connection box 6 is attached. Follow the normal procedure on the outside in the radial direction of the cable.

Next, a second embodiment in which the metal sheath is a lead sheath will be described. FIG. 4 is a sectional view of a cable showing a sheath diameter expansion state by a jig in the second embodiment. In the second embodiment, a tool such as the lead cover 26 is used as shown in FIG.
Expand 8a a little. Then, the tip-end taper-shaped instrument 24 shown in the first embodiment is inserted, for example, in the same manner as in the first embodiment to secure a space 10 having a sufficient size for accommodating the heat insulating sheet 14. Then, after inserting the heat insulating sheet 14 into the space 10, the lead cover 28 and the connection box 6 are sealed by a lead process through a normal process.

According to the first and second embodiments as described above, when the metal sheath (aluminum sheath 2, lead sheath 28) and the connection box 6 are sealed by lead, the portion 12 to be lead is formed.
Since the heat insulating sheet 14 is inserted inside the cable radial direction and outside the cable core 8, the cable insulator forming the outer portion of the cable core 8 can be reliably protected from the lead heat. Therefore, it is not necessary to wrap kraft paper, PML, or the like on the outermost layer of the cable core as in the conventional case.
Therefore, the cable insulator can be composed of the highly reliable all-semi-synthetic paper that should be originally provided.

In addition, as a measure against heat according to the present embodiment, the connection side end portions 2a and 28a of the metal sheath (aluminum sheath 2, lead sheath 28) are used.
Since it suffices to expand the diameter and insert the heat insulating sheet 14 into the void 10 formed thereby, the work using a relatively simple tool can be performed, and at the same time, on-site construction is possible.

Further, when the metal sheath is an aluminum corrugated tube as in the first embodiment, the corrugated tube is stretched in the longitudinal direction of the cable before cutting to deform the corrugated shape into a substantially cylindrical shape as described above. Since the gap 10 can be easily secured, the diameter expansion work of the metal sheath can be easily performed.

The present embodiment is a preferred embodiment of the present invention, and the technical scope of the present invention is not limited to this embodiment.

[0025]

As described above, according to the present invention, in the power cable connecting structure and the lead working method, the cable insulator is made of highly reliable all-semi-synthetic paper and the work is relatively simple. You can take measures against lead heat.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a cable connection structure of a first embodiment.

FIG. 2 is a side view of the cable showing a state in which the aluminum cover is stretched in the first embodiment.

FIG. 3 is a partial cross-sectional view of a cable showing a sheath diameter expansion state by inserting a device in the first embodiment.

FIG. 4 is a partial cross-sectional view of a cable showing a sheath diameter expansion state by opening a lead in the second embodiment.

[Explanation of symbols]

2 Aluminum sheath (an example of a metal sheath) 2a Connection side end of an aluminum sheath (corresponding to a connection side end of a metal sheath) 4 OF cable (an example of a power cable) 6 Junction box 8 Cable core 10 Void 12 Leaded Part 14 Heat insulating sheet (corresponding to heat insulating layer) 28 Lead cover (one example of metal sheath) 28a Lead side connection end (corresponding to metal sheath connection side end)

Claims (3)

[Claims] 1. A power cable connection structure having a metal sheath, wherein the metal sheath and the connection box are sealed by lead wire at the time of connecting the cable, wherein between the metal sheath and the cable core, A connecting structure for a power cable, characterized in that a void is formed by enlarging the diameter of the connection side end of the metal sheath, and a heat insulating layer is inserted inside the void and inside the leaded portion. 2. A lead method for sealing a metal sheath and a connection box at the time of connecting a power cable having a metal sheath, wherein a connecting side end portion of the metal sheath is expanded to have the metal sheath and the cable core. A lead wire manufacturing method for a power cable, characterized in that a gap is formed between the gaps, a heat insulating layer is inserted into the gap, and the metal sheath and the connection box are leaded outside the heat insulating layer in the cable radial direction. . 3. The method of lead work for a power cable according to claim 2, wherein an aluminum corrugated pipe is used for the metal sheath.