JP7281995B2 - Cable repair method and cable repair structure - Google Patents

Description

The present invention relates to a cable repair method and a cable repair structure.

Crosslinked polyethylene insulated vinyl sheath cables (hereinafter referred to as "CV cables") are known as cables used in high-voltage power cable lines. CV cables are widely used from the viewpoint of easiness of installation and maintenance. Water tree is a phenomenon in which a small amount of moisture or foreign matter enters an insulator such as polyethylene, and this moisture permeates the insulator over time, causing insulation deterioration (breakdown of the insulator). be.

In order to suppress the occurrence of such water trees, for example, a cable with a waterproof layer in which a metal laminate layer is adhered to a sheath is known (see, for example, Patent Document 1). A cable provided with a water shielding layer exhibits excellent water shielding performance by preventing entry of moisture and the like.

JP 2018-45921 A

However, at sites where cables are laid, so-called traumatic events that damage cable sheaths occur, albeit infrequently. Every time such an event occurs, the damaged part is repaired with tape, etc., but in repairing the cable with the waterproof layer, it is not possible to maintain the waterproof performance before the damage. not present. Therefore, the cable, especially the cable with the impermeable layer, had a problem in maintaining the cable performance after repair.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cable repair method and a cable repair structure that are excellent in cable performance such as water impermeability and voltage resistance after repair in a damaged cable. to do.

In order to solve the above-mentioned problems, a first aspect of the present invention is a cable repairing method for repairing at least a damage to a cable jacket, comprising: applying an adhesive to the damage; a second step of covering the filled wound and forming a waterproof putty on the cable jacket; and a third step of forming a waterproof sheet on the waterproof putty. .

Further, after the third step, a fourth step of winding a pressing tape covering the waterproof sheet in a pressed state around the outer periphery of the cable, and a fifth step of winding a waterproof tape covering the pressing tape around the outer periphery of the cable. Further, it is preferable to have.

The fifth step includes a sixth step of winding a first waterproof tape that covers the pressure tape around the outer circumference of the cable, and a seventh step of winding a second waterproof tape that covers the first waterproof tape around the outer circumference of the cable. and preferably.

Moreover, it is preferable that the second waterproof tape is a PVC tape.

Moreover, it is preferable that the pressure tape is a self-fusing tape.

Moreover, it is preferable that the second step and the third step are repeated in a plurality of sets, with the second step and the third step being one set.

Moreover, it is preferable that the waterproof sheet is an aluminum sheet.

A second aspect of the present invention is a repair structure for a cable in which at least a damage occurring in a cable jacket is repaired, comprising: an adhesive part applied to the damage and filling the damage; and a waterproof putty formed on the cable jacket and a waterproof sheet formed on the waterproof putty.

According to the aspect of the present invention, excellent water-impervious performance can be exhibited by overlaying the waterproof putty and the water-impervious sheet on the adhesive embedded in the wounded portion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing the configuration of an exemplary CV cable applied to a cable repair method according to an embodiment of the present invention; 1 is a cross-sectional view schematically showing a repaired cable realized by a cable repairing method according to an embodiment of the present invention; FIG. In the cable repair method according to the embodiment of the present invention, (a) is a perspective view showing a state in which an adhesive is applied to the damaged portion of the cable, and (b) the portion to which the adhesive is applied is covered and the cable sheath is shown. It is a perspective view showing a state in which a waterproof putty is formed thereon, and (c) is a perspective view showing a state in which an aluminum sheet is formed on the waterproof putty. 1 is a perspective view showing (a) a state in which a waterproof putty is formed on the outer periphery of an aluminum sheet, and (b) a state in which an aluminum sheet is formed on the waterproof putty, in the cable repair method according to the embodiment of the present invention. It is a perspective view showing. In the cable repair method according to the embodiment of the present invention, (a) a perspective view showing a state in which a self-fusing tape is wrapped around the outer periphery of the cable to cover a portion where the aluminum sheet is formed, and (b) self-fusing. It is a perspective view showing a state in which a waterproof sheet is wrapped around an adhesive tape, and (c) is a perspective view showing a state in which a PVC sheet is wrapped around a waterproof sheet.

Preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiment shown below is merely an example, and can take various forms within the scope of the present invention.

<Cable configuration>
The configuration of a cable applied to the cable repair method according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the cable 1 is, for example, a CV cable with a waterproof layer, a conductor 2 located in the center, an inner semiconductive layer 3, an insulating layer 4 , an outer semi-conductive layer 5 , a shielding layer 6 , a waterproof layer 7 , an adhesive layer 8 and an anti-corrosion layer 9 .

The conductor 2 is made of, for example, copper, copper alloy, aluminum, aluminum alloy, or the like. The conductor 2 may be formed of either a solid wire or a stranded wire.
The internal semiconducting layer 3 is formed on the conductor 2 and is made of a semiconducting composition, for example, polyethylene or ethylene copolymer blended with a conductivity imparting agent such as carbon black.
The insulating layer 4 is formed on the inner semi-conductive layer 3, and a resin composition such as crosslinked polyethylene resin is applied.
The outer semiconducting layer 5 is formed on the insulating layer 4 and is made of a semiconducting composition like the inner semiconducting layer 3 .
The shielding layer 6 is composed of, for example, a single wire or a tape-like metal, such as copper and aluminum. The impermeable layer 7 is made of, for example, a cylindrical metal or the like, such as aluminum or lead.
The adhesive layer 8 bonds the impervious layer 7 and the anticorrosive layer 9 together, and may be made of a hot-melt adhesive, for example.
The anti-corrosion layer 9 constitutes the jacket of the cable 1, is formed on the waterproof layer 7 via the adhesive layer 8, and is made of, for example, polyvinyl chloride (PVC).
In addition, the configurations of the conductor 2, the inner semiconductive layer 3, the insulating layer 4, the outer semiconductive layer 5, the waterproof layer 7, the adhesive layer 8, and the anticorrosive layer 9 are merely examples, and are used in general power cables. Various materials, compositions, etc. are applied.

<Cable Repair>
A cable repair method will be described with reference to FIGS. 2 to 4. FIG. In the present embodiment, a method for repairing a cable when damage A occurs in the waterproof layer 7, the adhesive layer 8 and the anticorrosion layer 9 constituting the cable 1 will be described.

(Cable repair structure)
With reference to FIG. 2, the configuration of the cable after repair (cable repair structure) realized by the cable repair method according to the present embodiment will be described. The repaired cable 1 includes an adhesive 10 that fills the wound A caused in the waterproof layer 7, the adhesive layer 8, and the anticorrosive layer 9, a waterproof putty 20 that partially covers the adhesive 10 and the anticorrosive layer 9, and a waterproof putty 20. It has a waterproof sheet 30 that covers the

By applying the adhesive 10 to the wound A of the cable 1 , the wound A (dent) is buried until it reaches the surface of the anticorrosive layer 9 . The adhesive 10 is not particularly limited, and a commonly used adhesive is applied, but from the viewpoint of maintaining the insulation performance of the cable 1 after repair, it has insulation performance equivalent to that of the anticorrosion layer 9. is preferred. By filling the wound A with the adhesive 10, the voltage resistance performance equivalent to that of the existing cable 1 can be maintained.

The waterproof putty 20 is applied so as to cover the area including the adhesive 10 buried in the wound A and reaching the surface of the anticorrosive layer 9 and the peripheral area to which the adhesive is applied. As a result, intrusion of water or the like in a direction parallel to the axial direction of the cable 1 is prevented. Moreover, the waterproof putty 20 has an adhesive function for bonding the later-described waterproof sheet 30 and the anticorrosive layer 9 of the cable 1 . The waterproof putty 20 is not particularly limited, and a commonly used waterproof putty and a material corresponding to the putty are applied.

The waterproof sheet 30 is attached onto the anticorrosive layer 9 so as to cover the applied waterproof putty 20 . As a result, intrusion of water or the like in a direction perpendicular to the axial direction of the cable 1 is prevented. The impermeable sheet 30 is made of, for example, a metal foil such as aluminum from the viewpoint of impermeability. The impermeable sheet 30 is not limited to a metal foil such as aluminum, and may be made of various materials as long as they satisfy the required impervious performance.

As described above, in order to prevent moisture or the like from entering the adhesive 10 applied to the wound A, a multi-layer structure consisting of the waterproof putty 20 and the waterproof sheet 30 is provided to prevent the cable 1 from entering. The water imperviousness is enhanced in the direction parallel to the axial direction and in the direction perpendicular to the axial direction.

Further, the waterproof putty 20 and the waterproof sheet 30 are not limited to being formed one layer at a time, and can be applied to a case of forming multiple layers. For example, in a state in which the impermeable sheet 30 is formed on the waterproof putty 20, the waterproof putty 20 is applied on the impermeable sheet 30 in a frame shape along the periphery of the impermeable sheet 30, and further the applied frame-shaped A configuration in which a waterproof sheet 30 is affixed on the waterproof putty 20 may be employed (see FIG. 4). With such a configuration, the upper water impermeable sheet 30 is separated from the lower water impermeable sheet 30 and can follow the movement of the cable 1 .

(Cable repair method)
A cable repair method will be described with reference to FIGS. 3 to 5. FIG. In this embodiment, a method for repairing an injury A caused in one cable 1 in a cable bundle consisting of a plurality of cables will be described.
As shown in FIG. 3( a ), an adhesive 10 is applied to each of the plurality of wounds A (dents) generated through the waterproof layer 7 , the adhesive layer 8 and the anti-corrosion layer 9 in the jacket of the cable 1 . be. The adhesive 10 is applied until it reaches the surface of the anticorrosion layer 9 . As a result, the wound A is completely filled with the adhesive 10, and the impermeable layer 7, which has been exposed due to the occurrence of the wound A, is cut off from the outside.

Next, as shown in FIG. 3(b), in order to improve the water-impermeability of the adhered portion to which the adhesive 10 is applied, the anticorrosion layer 9 of the cable 1 is applied so as to cover the entire portion to which the adhesive 10 is applied. A waterproof putty 20 is applied thereon. As a result, the portion to which the adhesive 10 is applied is completely covered with the waterproof putty 20, so that the penetration of water or the like into the adhesive portion covering the wound A in the direction parallel to the axial direction of the cable 1 is prevented.

Next, as shown in FIG. 3C, an aluminum sheet 30 is attached as a waterproof sheet 30 onto the waterproof putty 20 applied to the surface of the anticorrosive layer 9 . Since the waterproof putty 20 has an adhesive function, the aluminum sheet 30 is adhered and fixed on the impermeable sheet 30 . This prevents entry of moisture or the like into the adhesive portion covering the wound A in the direction perpendicular to the axial direction of the cable 1 .

By repairing the cable 1 having the damage A based on the above steps, the adhesive 10 applied to the damage A is covered with the multilayer structure of the waterproof putty 20 and the aluminum sheet 30 . As a result, a cable repair structure (FIG. 2) having the same waterproof performance and withstand voltage performance as the cable 1 before the injury A occurred can be obtained.

In the cable repair method described above, the waterproof putty 20 and the waterproof sheet (aluminum sheet) 30 are formed one by one. can also be configured. Specifically, a configuration relating to a repair structure for the cable 1 as shown in FIG. 4 can be used.

As shown in FIG. 4( a ), in the state where the impermeable sheet (aluminum sheet) 30 is attached on the anticorrosive layer 9 by the above process (see FIG. 3( c )), the impermeable sheet (aluminum sheet) 30 A waterproof putty 21 is applied over the entire circumference of the outer circumference of the .

Next, as shown in FIG. 4(b), an aluminum sheet 31 is attached onto the applied waterproof putty 21. Next, as shown in FIG. Since the waterproof putty 21 has an adhesive function, the outer peripheral portion of the aluminum sheet 31 is adhered and fixed on the waterproof putty 21 . On the other hand, portions other than the outer periphery of the aluminum sheet 31 are not fixed to the waterproof putty 21 . With such a structure, the upper aluminum sheet 31 is separated from the lower aluminum sheet 30, so that the upper aluminum sheet 31 can follow the movement of the cable 1.

By repairing the cable as described above, a repair structure is formed in which a plurality of sets of multi-layered structures of waterproof putty and aluminum sheets (waterproof putty 20 and aluminum sheet 30, waterproof putty 21 and aluminum sheet 31) are formed. In addition to improvement in performance and withstand voltage performance, followability to movement of the cable 1 can also be improved. In the above configuration, an example in which the waterproof putty 21 is applied only to the outer circumference of the lower aluminum sheet 30 in the multilayer structure of the upper layer waterproof putty 21 and the aluminum sheet 31 has been described, but the present invention is not limited to this. A structure in which the waterproof putty 21 is applied to the entire surface of the lower aluminum sheet 30 is also applied.

Further, in the cable repair method according to the present embodiment, in order to further improve the waterproof performance of the cable 1 after repair, as shown in FIG. be able to. Below, the repair structure of the cable 1 in which two sets (waterproof putty 20 and aluminum sheet 30, waterproof putty 21 and aluminum sheet 31) of the multi-layered structure composed of the waterproof putty and the aluminum sheet shown in FIG. Then, the configuration for winding the tape will be described.

As shown in FIG. 5(a), in a state in which two layers of waterproof sheets (aluminum sheets) 30, 31 and two layers of waterproof putty 20, 21 are formed (see FIG. 4(b)), the self-bonding tape 40 is One layer is wound in a half-wrapped form so as to cover the repaired part and bundle a plurality of cables 1. - 特許庁As a result, since the cable 1 is wrapped with the self-bonding tape 40 in a pressed state, a sufficient surface pressure is secured against the lower layer aluminum sheet 30 that contributes to the protection of the injury A, and the repair structure is stably maintained. . The self-fusing tape wound around the cable 1 is not particularly limited, and commonly used tapes are applied.

Next, as shown in FIG. 5(b), a waterproof tape 50 is wrapped on the wound self-fusing tape 40 in a half-wrapped manner so as to cover the self-fusing tape 40. Next, as shown in FIG. Thereby, the waterproof performance of the repair structure of the cable 1 is further enhanced. The waterproof tape 50 wound around the cable 1 is not particularly limited, and a commonly used one is applied. Note that the waterproof tape 50 can be omitted depending on the required waterproof performance.

Next, as shown in FIG. 5(c), two layers of PVC (polyvinyl chloride) tape 60 are wrapped on the wound waterproof tape 50 in a half-wrapped manner so as to cover the waterproof tape 50 in a pressed state. The PVC tape 60 has a waterproof function. As a result, the waterproof performance of the repair structure for the cable 1 is further enhanced, and a pressing force is applied to the repaired portion, so that the repair structure for the cable 1 is more stably maintained. Although the PVC tape 60 is used in the present embodiment, it is not limited to this, and tapes based on other materials can be applied as long as the waterproof performance of the cable repair structure can be improved.

EXAMPLES Examples according to embodiments of the present invention will be described below. It should be noted that the following examples are merely examples for explaining aspects of the present invention, and the present invention is not limited to the examples.

(Example)
In this example, in order to verify the water impermeability by the repair method according to the present embodiment, the repair method according to the present embodiment was applied to a cable with damage, and the water impermeability of the cable was measured. A test was conducted to measure moisture permeability. Specifically, the insulation of a new 100 mm ² cable with a waterproof layer is extracted, and a 1.5 mm through hole ( A simulated cable was made by providing a wound).

The cable was repaired through the following steps (i) to (vii) with respect to the simulated cable with the trauma.
(i) An adhesive was applied to the formed wound, and the wound was filled until the adhesive reached the surface of the anticorrosion layer (see FIG. 3(a)).
(ii) A waterproof putty was attached to the surface of the anticorrosive layer so as to cover the adhesive applied in step (i) (see FIG. 3(b)).
(iii) An aluminum sheet was pasted on the waterproof putty formed in step (ii) (see FIG. 3(c)).
(iv) A waterproof putty was applied to the entire periphery of the aluminum sheet formed in step (iii) (see FIG. 4(a)).
(v) An aluminum sheet was pasted on the waterproof putty formed in step (iv) (see FIG. 4(b)).
(vi) A self-bonding tape was wrapped around the cable so as to cover the aluminum sheet formed in step (v) in a pressed state (see FIG. 5(a)).
(vii) A PVC tape was wound in the circumferential direction of the cable so as to cover the self-fusing tape wound in step (vi) in a pressed state (see FIG. 5(c)).

(Comparative example)
By the same method as in the above example, the insulation etc. of a new 100 mm ² cable with a water shielding layer was extracted, and a 1.5 mm thickness was applied to the cylindrical body consisting of the anticorrosion layer, the adhesive layer and the water shielding layer using a drill. A simulated cable was produced by providing a through hole (trauma). In the comparative example, the cable was not repaired as in the example, and the simulated cable was kept as it was.

(Moisture permeability test)
In the cables according to the above examples and comparative examples, the length of the simulated cable is adjusted to about 0.3 m, and end caps made of copper are attached to both ends of the tubular cable. The terminal cap is equipped with a dew point meter sensor that can observe changes in water content. The moisture permeability P was measured based on the formula.

[Formula 1]
P=Q/(2π・L・t・d)・ln(R ₂ /R ₁ ) (g・cm/(cm ²・day・mmHg))
Q: permeated water content (g)
d: saturated water vapor pressure (mmHg)
L: sample length (cm)
R ₁ : Inner diameter of impermeable layer (cm)
R ₂ : Sheath (anticorrosion layer) outer diameter (cm)
t: test time (day)

In the results of the moisture permeability test, if the moisture permeability value is less than the moisture permeability value of 5.1 × 10 ^-10 g cm / (cm ² day mmHg) required as a design standard, it will be marked as “○”. It was evaluated as "x" in other cases.

Table 1 shows the results of the moisture permeability test for the above examples and comparative examples.

As a result of the moisture permeability test, in the repaired simulated cable according to the example, the moisture permeability value after 30 days of the above test was 6.8 × 10 ^-11 g cm / (cm ² day mmHg), A result satisfying the moisture permeability value of 5.1×10 ⁻¹⁰ g·cm/(cm ² ·day·mmHg) required as a design standard was obtained. Furthermore, the moisture permeability value in the example is about the same as the moisture permeability value of 2.1 × 10 ^-11 g cm / (cm ² day mmHg) for a new cable with a waterproof layer that was tested under the same conditions. As a result, the effectiveness of this repair method was confirmed.
On the other hand, in the simulated cable according to the comparative example (simulated cable that was not repaired), water entered the sample immediately after the start of the moisture permeability test, making measurement impossible.

In the above embodiment, the cable repair method and the cable repair structure have been described by taking the CV cable with the waterproof layer as an example, but the present invention is not limited to this. Applied cables also apply to cables without waterproof layers and other power cables.
Further, in the above-described embodiment, the cable 1 having the damage A in the waterproof layer 7, the adhesive layer 8, and the anticorrosive layer 9 was described as an example to be repaired, but the present invention is not limited to this. The cable to be repaired has damage A only on the anticorrosion layer 9, especially the cable that has damage A on the constituent members outside the water shielding layer, including the water shielding layer, depending on the position and size of the damages A. applied regardless. On the other hand, when repairing the cable having the damage A in the structural member inside the impermeable layer, it is necessary to perform the repair by a method different from the above embodiment, but the repair method according to the above embodiment and Repair structures may be applied.

1 Cable 2 Conductor 3 Inner Semiconducting Layer 4 Insulating Layer 5 Outer Semiconducting Layer 6 Shielding Layer 7 Waterproof Layer 8 Adhesive Layer 9 Anticorrosion Layer 10 Adhesive 20 Waterproof Putty 21 Waterproof Putty 30 Waterproof Sheet (Aluminum Sheet)
31 waterproof sheet (aluminum sheet)
40 self-bonding tape 50 waterproof tape 60 PVC tape A injury

Claims (8)

In a cable repair method for repairing at least damage to the cable jacket,
a first step of applying an adhesive to the wound and filling the wound with the adhesive;
a second step of covering the filled wound and forming a waterproof putty on the jacket of the cable;
a third step of forming a waterproof sheet made of metal on the waterproof putty;
A cable repair method comprising: 2. The method of repairing a cable according to claim 1, wherein the waterproof sheet is an aluminum sheet. After the third step, a fourth step of winding a first tape covering the impervious sheet in a pressed state around the outer periphery of the cable;
The cable repair method according to claim 1 or 2, further comprising a fifth step of winding a second tape covering the first tape in a pressed state around the outer periphery of the cable. 4. The method of repairing a cable according to claim 3 , wherein the first tape is a self-fusing tape. 5. The cable repair method according to claim 3 , wherein the second tape is a PVC tape. Between the fourth step and the fifth step,
Further comprising a sixth step of winding a waterproof tape covering the first tape around the outer circumference of the cable,
The cable repair method according to any one of claims 3 to 5, wherein in the fifth step, a second tape covering the waterproof tape in a pressed state is wound around the outer circumference of the cable. The cable repair according to any one of claims 1 to 6, wherein the second step and the third step are repeated in a plurality of sets, with the second step and the third step being one set. Method. In a cable repair structure in which at least the damage caused to the outer jacket of the cable is repaired,
an adhesive applied to the wound and filling the wound;
a waterproof putty covering the adhesive part and formed on the jacket of the cable;
a waterproof sheet made of metal formed on the waterproof putty;
A cable repair structure comprising:

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