JP3171657B2 - Cable connection end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable connection end, and more particularly to a cable connection end useful for connecting a high-pressure rubber-plastic insulated cable having an outer semiconductive layer of a free stripping type.

[0002]

2. Description of the Related Art In recent years, a so-called free stripping type high-pressure rubber / plastic insulated cable having an external semiconductive layer formed of a material having good releasability and provided with an external semiconductive layer has been developed. Attention has been paid to the fact that the stripping operation is easy and a smooth exposed surface of the cable insulator is obtained.

[0003] By the way, the connection part of this kind of cable is
As in the case of a conventional cable having a bond type outer semiconductive layer, as shown in FIG.
A non-crosslinked semiconductive rubber / plastic tape is wound over the wire and heated to form a tape wound mold layer 4, on which a stress cone (not shown) for electrolytic relaxation is mounted. It is composed. In the figure, 5 is a conductor, 6 is a cable shielding layer, and 7 is a cable sheath.

[0004]

However, the external semiconductive layer 2 of the free stripping type is formed thicker than that of the bond type due to the characteristics of the material.
Therefore, when a winding layer of a semiconductive rubber / plastic tape is provided on the outer semiconductive layer 2 and heated,
As a result of the concentration of the semiconductive rubber / plastic tape melted during the heating molding in the gap formed at the cut end of the outer semiconductive layer 2, FIG.
As shown in (1), there is a problem that the lower portion of the cut end of the free-striping type external semiconductive layer 2 bites into the cable insulator 3 softened by heating, thereby deteriorating the dielectric breakdown characteristics. This has been a major factor in preventing the free-stripping type of the external semiconductive layer in the ultra-high voltage cable of 66-77 kV class or more.

Therefore, it has been considered to chamfer the cut end of the external semiconductive layer 2 with a knife or a file to apply a taper process. However, since the free stripping type external semiconductive layer 2 itself is soft, Unlike the bond type external semiconductive layer, it could not be easily cut off, requiring a great deal of time and skill in work, and possibly damaging the cable insulator 3. In addition, even if the cut end of the outer semiconductive layer 2 can be tapered, the cut end is turned up because the free stripping type external semiconductive layer 2 itself is soft.

The present invention has been made in order to solve such a problem, and a cable connection in which a cut end of a free stripping type external semiconductive layer does not bite into a cable insulator and has excellent workability. The purpose is to provide an end.

[0007]

According to the present invention, there is provided a cable connecting end having a free end exposed by stepping off the end of the cable.
A non-crosslinked semiconductive rubber / plastic tape is wound on the cable insulating layer following the cut end of the cable type semiconducting outer layer, and the cable outer half is further wound. A non-crosslinked semiconductive rubber / plastic tape is wound from the conductive layer to the cable insulating layer, and then heated to fuse the semiconductive rubber / plastic tape wound layer and the diameter matching portion together. It is characterized by the following.

[0008]

In the cable connection end of the present invention, the diameter of the cable outer semiconductive layer is formed by winding a rubber / plastic tape on the cable insulating layer following the cut end of the cable outer semiconductive layer. Since the gap at the cut end is eliminated, even if the rubber / plastic tape at the diameter matching portion is melted during the heat molding, the tightening pressure does not concentrate below the cut end of the semiconductive layer outside the cable.
Therefore, even with a thick cable outer semiconductive layer of the free stripping type, the cut end does not cut into the cable insulator, and the cable has excellent dielectric breakdown characteristics.

Moreover, no special tools or techniques are required for the formation, and the workability is excellent.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged sectional view showing a main part of a connection end of a 66 kV class CV cable according to an embodiment of the present invention.

In FIG. 1, reference numeral 8 denotes an insulator 9 made of cross-linked polyethylene on a conductor (not shown), and an external semiconductive material formed by extrusion of a semiconductive composition based on EVA having a high degree of polymerization of vinyl acetate as a base polymer. Layer 10, a free stripping type external semiconductive layer that can be easily peeled off without fusing with the crosslinked polyethylene insulator 9, a shielding layer (not shown) made of a copper tape wound, and extrusion of a vinyl chloride resin. 2 shows a stepped end of a CV cable in which sheaths (not shown) are sequentially applied.
The free stripping type external semiconductive layer 10 is cut in a plane perpendicular to the cable axis, that is, the end is not chamfered by a knife or the like.

Thus, the connection end of this embodiment is a non-crosslinked semiconductive polyethylene over a predetermined length on the cable insulator 9 following the cut end of the free stripping type external semiconductive layer 10. Diameter adjustment part 1 by winding tape
Further, a non-crosslinked semiconductive polyethylene tape winding layer 12 is provided on the diameter matching portion 11 so as to extend from the cable outer semiconductive layer 9 to the cable insulating layer 10. The conductive rubber / plastic tape winding layer 12 and the diameter matching portion 11 are integrally fused.

In order to form the connection end of such a cable, first, the end of the CV cable is stepped off and exposed, and the cable insulation layer 9 is connected to the cut end of the free stripping type external semiconductive layer 10. Next, a non-crosslinked semiconductive polyethylene tape is wound over a predetermined length so that the outer diameter is the same as that of the outer semiconductive layer 10 to form the diameter adjusting portion 11. Next, a non-crosslinked semiconductive polyethylene tape is further wound on the diameter matching portion 11 so as to have a predetermined thickness and shape across the cable outer semiconductive layer 10 and the cable insulating layer 9. Thereafter, a heat-shrinkable tube is applied onto the non-crosslinked semiconductive polyethylene tape winding layer 12, and a heat-resistant and high-strength plastic tape such as a polyimide tape is pressed and wound thereon, followed by pressing. By heating while heating, the non-crosslinked semiconductive polyethylene tape winding layer 12 and the diameter matching portion 11 are integrally fused to form the connection end having the above-described configuration.

At the cable connection end thus formed, there is no gap at the cut end of the free stripping type external semiconductive layer 9, so that when heated, the diameter matching portion 11 and the non-crosslinked semiconductive Even if the rubber / plastic tape winding layer 12 is melted, stress does not concentrate at one location, and the lower portion of the cut end of the external semiconductive layer 10 does not cut into the cable insulating layer 9. Therefore, the dielectric breakdown characteristics at the connection end of the cable are improved, and it is possible to form a cable connection portion having excellent electrical characteristics using the same.

Incidentally, in order to examine the electrical performance of the above embodiment, an AC withstand voltage test (withstand an applied voltage of 175 kV for 3 hours), a lightning impulse withstand voltage test (applied voltage of 535 kV)
), Heat cycle test for 30 days (conductor temperature 90 ° C, applied voltage 90kV, 8 hours ON 16 hours OF
F) and the subsequent AC destruction test (applied voltage 300k
The results of performing V) were all good.

The above embodiment is an example in which the present invention is applied to the connection end of a 66 kV class CV cable. However, the present invention is not limited to such an embodiment, and a free stripping type external half is used. The same effects as in the above embodiment can be obtained by applying the present invention to various cables of a low voltage to an ultra high voltage having a conductive layer. However, the penetration of the cut end of the outer semiconductive layer into the cable insulating layer is a major problem at 66 kV.
It is particularly useful when applied to cables of class or higher.

[0018]

As described above, according to the cable connection end portion of the present invention, the cut end of the external semiconductive layer is prevented from biting into the cable insulating layer, and the reliability of the cable with improved dielectric breakdown characteristics is improved. A high connection can be formed. Moreover, the work is easy and can be formed in a short time, and no special skill is required.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing a main part of a cable connection end according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional cable connection end.

FIG. 3 is a cross-sectional view showing a state of a cut end of an external semiconductive layer at a conventional kale connection end.

[Explanation of symbols]

 8 CV cable end portion stripped off 9 Cable insulation layer 10 Free stripping type external semiconductive layer 11 Diameter matching portion 12 Non-crosslinked semiconductive polyethylene tape Wound layer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02G 15/064 H01R 43/00

Claims (1)

(57) [Claims] 1. A free end exposed by stepping off an end of a cable.
On the cable insulating layer following the cut end of the stripping type cable external semiconductive layer, a non-crosslinked semiconductive rubber / plastic tape is wound to form a diameter-matching portion. A non-crosslinked semiconductive rubber / plastic tape is wound over the cable outer semiconductive layer and over the cable insulation layer, and heated to fuse the semiconductive rubber / plastic tape winding layer and the diameter matching part together. A cable connection end, characterized in that: