JPS6066607A - Method of connecting power cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to a method for connecting electric power cables, and more specifically, to improving an internal semiconducting layer formed at a connecting portion of a molded CV cable. This article relates to how to connect electric power cables.

2. Description of the Related Art Conventionally, it is well known that semiconductive heat-shrinkable tubes are used for connecting portions of high-voltage electric cables.

This heat-shrinkable tube is widely used because it alleviates the electric field generated on the surface of the connection portion of the conductor, improves the finish of the surface, and has excellent connection workability.

The state of use of the heat-shrinkable tube will be explained below with reference to the drawings. In FIG. The conductor coating layer 4 such as the conductive layer 2 and the cable insulation layer 3 is peeled off, and the exposed conductors 5 are brought into contact with each other, and the connection points are compressed and connected by a pmxam, su conductor connection sleeve 6. The connection point is further covered by the heat-shrinkable tube 7 and the molded insulator 8.

The heat-shrinkable tube 7 arranged as described above is placed at least on the cable insulating layer 3, preferably on the outermost layer of the cable (not shown in the figure), at a distance from the conductor connection point so as not to interfere with the conductor connection work. ) is pre-inserted on top.

When the conductor 5 is connected, the heat-shrinkable tube 7 is moved to the conductor connection location, and while its both ends are overlapped with the cable inner semiconductive layer 2, it is heat-shrinked until it comes into close contact with the exposed conductor part, thereby connecting the conductor. Cover the area. The heat-shrinkable tube 7 used in this manner must have an inner diameter at least larger than the cable insulation layer 3 before heat-shrinking.

On the other hand, as the voltage of electric power cables increases, the thickness of the insulating layer 3 increases and the outer diameter of the cable increases.
The heat-shrinkable tube 7 also required a larger shrinkage amount. However, due to the characteristics of the heat-shrinkable tube 7,
Since there is a limit to the shrinkage rate, especially in the case of the above-mentioned ultra-high voltage cable, the cable is placed over the conductor connection portion without being able to sufficiently shrink.

If the heat-shrinkable tube 7 was not sufficiently shrunk, the tube 7 would become softer and thermally expand than the inner half of the cable in contact with its end, resulting in local protrusions 9.

The gap or local protrusion 9 became a fatal defect for the dielectric strength of the conductor connection.

One way to prevent the occurrence of such gaps or local protrusions 90 is to use a heat-shrinkable chewif whose inner diameter upon final contraction is sufficiently smaller than that of the cable internal semiconductive layer 2.

That is, the heat-shrinkable tube 7 that has finished shrinking while leaving a sufficient amount of shrinkage retains a shrinkage force corresponding to the amount that has not yet been shrunk, and can be brought into close contact with the cable internal semiconducting layer 2 with this shrinkage force, thereby reducing the gap. And the occurrence of local protrusions 9 could be prevented.

However, the heat-shrinkable tube 7 provided as described above,
In the case of the above-mentioned ultra-high voltage cable, it is required to have a large inner diameter before shrinking, and also to have a large shrinkage ratio.

However, manufacturing a heat-shrinkable tube with a high shrinkage rate requires high-grade materials and advanced processing techniques, resulting in high manufacturing costs.

An object of the present invention is to eliminate the above-mentioned drawbacks, use a heat-shrinkable tube having a commonly used shrinkage ratio, and prevent the above-mentioned gaps or local protrusions from occurring in the internal semiconductive layer at the connecting portion of the power cable. An object of the present invention is to provide a method for connecting the power cable.

SUMMARY OF THE INVENTION That is, the object of the present invention is to further convert the end portion of the semiconductive heat-shrinkable tube that covers the entire conductor exposed at the connection portion to another heat-shrinkable tube having a different heat shrinkage ratio or outer diameter. This is achieved by a method for connecting a power cable, characterized in that an internal semiconducting layer is formed at the connecting portion by covering the connecting portion with a tube and heat-shrinking the heat-shrinkable tubes.

EXAMPLE Hereinafter, an example of the present invention will be described based on a connection work process with reference to the drawings.

In FIG. 2, similarly to FIG. 1, two electric power cables 10a and 1Ob to be connected have conductors 11 exposed at their ends facing each other, and the conductors 11 are connected to a conductor connecting sleeve wire rod 12. It has been compressed by. A semiconductive heat-shrinkable tube (hereinafter referred to as the main tube) 13 that covers the entire conductor exposed at this connection part is inserted in advance onto the insulating layer 14 of the one electric cable sol tab. There is.

Further, two semiconductive heat-shrinkable tubes (hereinafter referred to as auxiliary tubes) 15 having a smaller and shorter inner diameter before contraction than the main tube 13 are connected to the power cables 10a and 10b', respectively. Cable internal semiconductive layer 16
It is inserted across the upper and insulating layer pencil ring portions 17.

Next, as shown in FIG. 3, after connecting the conductor 11,
The main tube 13 is moved to the conductor connection location, and its both ends are provided so as to cover the cable inner semiconductive layer 16 and heat-shrinked. As a result, the main tube 13 is brought into close contact with the conductor connection location, and its end portion is brought into close contact with the semiconductive layer 16 within the cable. Further, the two auxiliary tubes 15, 1.5 are respectively moved to positions spanning the main tube 13 and the cable internal semiconductive layer 16, and are heat-shrinked to form the main tube f13 and the cable internal semiconductive layer 16. It is closely followed.

The connection portion is further covered with a molded insulator (not shown) as in the prior art to complete the connection process.

As described above, the main tube 13 and the auxiliary tube 15 are each heat-shrinked to form an internal semiconductive layer at the connection portion.

The power cable 10a and the fob have an outer diameter of 100 mm, and the semiconductive layer 16 inside the cable has a diameter of 4°. Therefore, the inner diameter of the main tube 13 and the auxiliary tube 15 before contraction is In this case, the main tube 13 is 1
The auxiliary tube 15 has a diameter of 20 mm, the auxiliary tube 15 has a diameter of 60 mm, and the tubes 13 and 15 have a contraction ratio of 3 times, which is commonly used.

Therefore, when the main tube 13 stops contracting with its end in contact with the cable inner semiconductive layer 16, its final contracted diameter is set to 40111. On the other hand, since this final contraction diameter value is also the contraction limit value of the main tube 13, the main tube 13 is in close contact with the cable internal semiconductive layer 16 with almost no contraction force remaining. Become. Further, the auxiliary tube 15 has a final contraction diameter of 20
Although it can be shrunk to a diameter of 1111, since it is in close contact with the cable internal semiconductive layer 16 through the main tube 13,
(The contraction will be stopped at 1+i diameter, and the remaining 2
(The amount of contraction of 1+vi is maintained. In other words, the auxiliary tube 15 is provided with a contraction force equivalent to that of the main tube 15 being stretched twice.
is brought into close contact with the cable internal semiconductive layer 16.

In the above example, the same shrinkage force can be obtained by using only a heat-shrinkable tube whose inner diameter before shrinkage is 60 mtn, but the connection using such a heat-shrinkable tube As shown in FIG. 4, this method involves making the pencil ring part 17 unduly long because it is necessary to move the tube 18 away from the cable insulation layer pencil ring part 17 in order to secure a connection point when connecting the conductor. I don't like it.

In addition, the auxiliary tube 15 has a higher shrinkage rate,
For example, by forming the tube with a material having a high melt viscosity or a material having a high heat deformation temperature, the adhesion with the end portion of the main tube 13 is further ensured, and the occurrence of the local protrusions 9, etc. is ensured. Prevented.

Further, the main tube 13 is connected to the cable semi-conductive layer 16.
The length of the tube 13 may be overlapped with the tube 13.
The auxiliary tube 15 may be provided with a length sufficient to contact the cable semiconductive layer 16 and cover the exposed conductor, but in the case of the former case, the auxiliary tube 15 is not necessarily semiconductive. There's no need. However, if it is set up like the latter,
The auxiliary tube 15 has semiconductivity,
The auxiliary tube 15 and the main tube 13 ensure a semiconductive layer at the connection portion.

Effects of the Invention As described above, according to the connection method of the present invention, multiple types of heat-shrinkable tubes with different heat shrinkage ratios or outer diameter dimensions are used at the connection portion of the power cable, and the conductor is exposed as in the conventional method. By providing a main tube that covers the entire section and an auxiliary tube that further covers the ends of the main tube, it is possible to completely prevent local protrusions that occur on the internal semiconductive layer, which were the biggest defect in the connection section. It has an effect.

Furthermore, since the present invention uses a heat-shrinkable tube having a normal heat-shrinkage rate that is formed using inexpensive materials and easy processing techniques, the connection of the electric cable itself does not incur any particular increase in costs.

In addition, since two types of heat-shrinkable tubes with different inner diameters before shrinkage are used, it has various advantages such as being able to easily accommodate power cables with large outer diameters depending on the combination of the tubes. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a connecting portion for explaining a conventional electric power cable connecting method, and FIGS. 2 and 3 are partial cross-sectional views of a connecting portion for explaining a connecting method of electric power cables according to the present invention. FIG. 4 is a partial cross-sectional view of a connecting portion illustrating an unfavorable arrangement of the heat-shrinkable tube before heat-shrinking. 9...Local protrusion, 1θa, lOb...
Electric cable, 11...Conductor, 13...
・Heat-shrinkable tube (main tube), 14... Insulating layer, 15... Heat-shrinkable tube (auxiliary tube), 16... Semi-conductive layer inside the cable, 17...
... Insulating layer bencillin agent patent attorney Sagbe. Display of God 1 Incident 11jif (158 Special FF K No. 173759
No. 2 Name of the invention Method for vulcanizing the sheath of a flat type tire cable 3 Relationship with the famous thing 41 that requires amendments Applicant's office Address 2-1-2 Marunouchi, Chiyoda-ku, Tokyo Name (5)
12) aRepresentative of Kasakasugan Co., Ltd.No'''Yi'1iYi 4th generation P-1 "person'"100 East Q Toseni (Taku L
5. ) U-chome, No. 2 Subject of residence amendment (1) Full text of the specification. (2) Drawing plan. Contents of amendment (1) As shown in the attached sheet. Attachment E 1 Catalog of antiquities (1) Correction specification 1 copy (2) Original drawings 1 copy - or more - Correction Akira III Book 1, Title of invention Flat-type Ki I / Butai A7 Ouvre sheath vulcanization Method 2 is characterized by directly winding a general flat type 21 [-] pigtail A7 cable directly around a vulcanizing drum and vulcanizing the sheath. How to vulcanize the sheath of a flat cabtyre cable. 3. Detailed Description of the Invention [Background and Object of the Invention] The present invention relates to a method for vulcanizing the sheath of a flat cabtyre couple. Conventionally, the sheath vulcanization methods for general flat type cab-ties 17/7-pull include coating a vulcanizing vessel on the sheath and vulcanizing it, continuous extrusion vulcanization (VCV, etc.), and straight horizontal vulcanization. However, all methods have drawbacks such as size restrictions and the need for a large number of processing steps. The purpose of the present invention is to overcome the above-mentioned drawbacks of the prior art,
To provide a sheath vulcanization method capable of manufacturing a general type flat-view cabtie 17 cable at low cost. [Summary of the Invention] The gist of the present invention is to employ a can vulcanization method as a method for vulcanizing the sheath, and to perform vulcanization without applying a lead coating for vulcanization or the like on the cable. In addition, when vulcanizing a general flat-type cable with a bare drum spring color, the rubber may become thermally softened during sheathing + fr, and the cable may be crushed or deformed by the own vehicle, etc., even when the number of windings reaches 2 to 3. As a solution to this problem, there is a possibility that the sheath may bulge when the steam is removed after vulcanization for a specified period of time.As a solution to this problem, it is necessary to create a sail with an appropriate thickness and width that matches the cable's \J method between the cable layers. It is desirable to prevent warpage and deformation by inserting an IJ@ tape and rotating the vulcanization drum in the forward or reverse direction at low speed during vulcanization. When venting, it is desirable to avoid bulging of the sheath by maintaining a balance between the internal pressure inside the cable and the pressure inside the can without reducing the pressure as rapidly as possible. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Fig. 1 shows a cross section of a general type flat cabtie V cable, in which three power line cores each consisting of a conductor 1 and an insulator 2 extruded and coated are arranged in parallel, and the circumference of these three power line cores is ''Secondly, the sheath 3 is formed by extrusion. Now, as shown in FIG.
Roll in stages. At this time, an intervening material 12 such as canvas is inserted between the layers (interstages) of the cable 11 as necessary. Next, the vulcanizing drum 6 prepared in this way is shown in FIGS. 2 and 3.
As shown in the figure, the unvulcanized cable 11 is assembled into a vulcanizing can 5 and the sheath of the unvulcanized cable 11 is vulcanized. In the vulcanizing can 5, a vulcanizing drum 6 is arranged on an under roll 7 so as to be able to rotate as appropriate. The under roll 7 is connected to a drive motor 8, and by operating the motor 8,
The vulcanization drum 6 is configured to be able to be rotated as appropriate from the outside of the can 5. In addition, in Figure 2, 9 is a steam valve, 10
is a steam exhaust valve. Vulcanization conditions vary depending on the type of sheath rubber, but in the case of this type of couple of 3x150 knitting and 2 classes, the vulcanization temperature is usually 150°C (vapor pressure 4.0Ky).
/α2), vulcanization time is 40 minutes, exhaust time is 120 minutes, and during vulcanization, the vulcanization drum is rotated in forward and reverse U rotations (interlocked with a timer, automatic operation) to prevent soaking, deformation, and swelling of the sheath. It can be prevented. [Effects of the Invention] According to the present invention, the number of processing steps is smaller than that of the conventional lead vulcanization method, and it is also possible to work on large-sized products compared to the CV method, and its industrial value is extremely large. 4. Brief explanation of the drawings Figure 1 is a partial perspective view of a general type flat cabtire cable, Figure 2 is a vertical cross-sectional view of a vulcanized can, and Figure 3 is the TV shown in Figure 2.
4 is an explanatory view showing a V% state in which a flat cabtire cable is directly connected to a vulcanizing drum and a canvas is inserted between the layers. 1: Conductor, 2: Insulator, 3: Sheath, 5: IQ can,
6: vulcanizing drum, 7: under CI-J, 8: under roll drive motor, 9: steam vent, 10: steam exhaust valve, 11: flat cable, 12: sail 11 (intervening).弗 1st eye 2nd eye Kaya 3rd eye 4th eye

Claims (1)

[Claims] The end of the semiconductive heat-shrinkable tube that covers the entire conductor exposed at the connection part is covered with another heat-shrinkable tube having a different heat shrinkage ratio or outer diameter, and the heat-shrinkable tube is A method for connecting electric power cables, characterized in that an internal semiconducting layer is formed in each of the connection parts by heat shrinking.