JP2915344B2 - Insulating sheet for connection of insulated power cable and method of winding the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating sheet for a connection portion of an insulated power cable suitable for use as a connection portion for molding and connecting a crosslinked polyethylene insulated power cable (CV cable) and a method of winding the same.

[0002]

2. Description of the Related Art In general, a cross-linked polyethylene insulated power cable used for power transmission and distribution at a high voltage or higher is connected to conductors b, a from the ends a1, a1 of both power cables a, a as shown in FIG. In order to expose b, the inner semiconductive layers c and c at the ends a1 and a1, the crosslinked polyethylene insulators d and d, the outer semiconductive layers e and e, the metal shielding layers f and f, and the cable sheath g and Strip off g appropriately. In particular, for the insulators d, d, the tip side is made to have a small diameter.

The conductors b, b are compression-connected to each other by a conductor connection pipe h, and a connection portion semiconductive layer i, etc. is formed on the surface of the connection portion formed by the compression-connected conductors b, b and the conductor connection pipe h. Is formed thereon, and a reinforcing insulating layer j is formed thereon to provide insulation. After the outer semiconductive layer k is formed on the outer peripheral surface of the reinforcing insulating layer j, the entire connection portion is covered with a protective body.

[0004] The reinforcing insulation layer j is an important part whose insulation performance determines the electrical performance of the cable connection part.
Conventionally, various techniques for forming the insulation have been developed and put to practical use.

Conventionally, as a technique for connecting a crosslinked polyethylene insulated power cable of 66 to 220 kV class, there is a joint method (tape joint) in which a self-fusing rubber tape is wound to form insulation at a connection portion. A non-crosslinked polyethylene tape containing a cross-linking agent is wound and then molded to form an insulation at a connection portion by a joint method (TMJ). The uncross-linked polyethylene resin containing a cross-linking agent is extruded and then molded and connected. The joint method (EMJ) for forming the insulation of the part, the joint method (PJ) for forming the insulation of the connection part by combining a rubber stress cone (pre-mold insulator) manufactured in advance at the factory and an epoxy insulation unit on site, and the like. is there.

[0006] Uncrosslinked EP containing a crosslinking agent (ethylene
After wrapping a (propylene) rubber tape, put it in a mold that can be heated and pressurized, and mold it to form insulation at the connection part (EPR mold joint). There is a cost advantage over TMJ. However, the quality is inferior, but at present, the TMJ has taken over the share.

[0007]

However, 154
In a crosslinked polyethylene insulated power cable of kV or more, the above-described TMJ is mainly used in terms of insulation performance, but has the following disadvantages in terms of construction environment and construction time. That is, in order to wind an uncrosslinked polyethylene tape containing a crosslinking agent, it is necessary to strictly control the cleanness of the construction environment. For this reason, although it takes only 1 to 2 hours to wind the uncrosslinked polyethylene tape, it took more than half a day (TMJ) to prepare the insulation construction environment by installing a clean room or the like. In addition, when molding a non-crosslinked polyethylene tape wound layer containing a crosslinker, a long working time is required to control heating and cooling (especially slow cooling is required). Therefore, the time and cost for the entire connection work of the power cable have been too high.

On the other hand, in the case of a crosslinked polyethylene insulated power cable of 66 to 77 kV class, tape-type joints, which are relatively unrestricted by the construction environment, have a short construction time, and are most excellent in cost, are widely used. In the case of a joint, it was difficult to apply it to a joint of 154 kV class or more in terms of insulation performance because the tapes were simply stuck together with an adhesive layer.

The EPR mold joint has an excellent workability as described below. That is, the bonding condition between the uncrosslinked EP rubber tape containing the crosslinking agent and the cable insulator is easier than the polyethylene containing the crosslinking agent, and
Since slow cooling during cooling is not required, the construction time is short. In addition, since there is no remarkable deterioration in the characteristics of foreign matters, it is not strict to control the cleanliness of the working environment.
Therefore, installation of a clean room or the like is unnecessary, so that it is possible to easily and quickly prepare an insulation construction environment. Therefore, it is more advantageous than the TMJ in terms of construction environment and construction time.

However, conventional uncrosslinked E containing a crosslinking agent
The P rubber tape cannot be mechanically wound using a winding machine, and since it is manually wound, the amount of air to be wound in varies greatly, and the skill of the winder is required. A step is easily formed on the outer peripheral surface,
Shaping work such as the stress cone rising part was necessary. For this reason, there has been a problem that the insulating layer and the external semiconductive layer cannot be collectively molded.

Further, in the conventional insulating tape, since the tape width is constant, it is necessary to move the tape many times in the axial direction of the power cable when winding the insulating tape.
At the same time, in order to obtain the necessary cross-sectional area and shape of the reinforcing insulating layer, a very large number of insulating tapes must be turned, which requires a long working time. In addition, there is a problem that skill is required to wind the tape properly so that air is not entangled between the tape layers, and quality is likely to vary depending on the skill of the winder.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. In connection with an insulated power cable, the time required for forming a reinforcing insulating layer can be shortened to improve on-site workability. Insulating sheet at the connecting portion of insulated power cable and method of winding the same so as to eliminate variations in quality due to the skill of the hands and to enable simultaneous molding of the insulating layer of the uncrosslinked EP rubber tape containing the crosslinking agent and the external semiconductive layer The task is to provide

[0013]

The present invention has the following arrangement to solve the above-mentioned problems. The invention according to claim 1 is a connecting portion for connecting insulating power cables at a connecting portion of the insulated power cable, in which a conductor of both power cables to be connected is exposed, an external semiconductive layer is peeled off, and cable insulation is performed. A connection part insulating sheet that is wound around the outer periphery of the cable insulator and the inner semiconductive layer in a state where the body is tapered and the conductors are connected by a conductor connection pipe, but the connection part internal semiconductive layer is formed on the outer peripheral surface. In the connection portion insulating sheet, the sheet width changes along the sheet winding direction based on the sheet thickness, the interval between the winding portions, and the target winding shape, and the winding shape becomes the target winding shape.

According to the present invention, the connecting portion insulating sheet is wound around the first valley between the inner semiconductive layer and the cable insulator, and corresponds to the width between the slopes in the valley. A first insulating sheet portion whose sheet width is changed and the winding shape is substantially the same diameter as the inner semiconductive layer; an outer surface of the inner semiconductive layer and the wound first insulating sheet portion; In the second valley formed with the slope,
The second is to change the sheet width in accordance with the width between the slopes of the insulators of both power cables and to make the winding form substantially the same diameter as the insulators.
Wrapping around the outer peripheral surface of the insulating sheet portion, the cable insulator, and the wrapped second insulating sheet portion, and changes the sheet width corresponding to the reinforcing insulating portion winding shape targeted at the connection portion. And a third insulating sheet portion.

According to a second aspect of the present invention, the connecting portion insulating sheet comprises:
A first insulating sheet portion, a second insulating sheet portion, and a third insulating sheet portion;
2. The insulating sheet according to claim 1, wherein the insulating sheet portion is formed as a continuous integrated sheet.

According to a third aspect of the present invention, the connecting portion insulating sheet is
Non-crosslinked or semi-crosslinked EP rubber containing a crosslinking agent, those formed of a single polyolefin layer such as polyethylene, or a crosslinked EP rubber layer, or non-crosslinked,
Alternatively, it has a layer structure in which an uncrosslinked EP rubber layer containing a crosslinking agent is adhered to at least one surface of a non-crosslinked, semi-crosslinked, or crosslinked polyolefin layer such as semi-crosslinked or crosslinked polyethylene. The insulating sheet for a connecting portion of an insulated power cable according to claim 1, wherein the insulating sheet is a member.

According to a fourth aspect of the present invention, there is provided a connecting portion for connecting insulated power cables, wherein the conductors of the two power cables to be connected are exposed, the outer semiconductive layer is peeled off, and the cable insulator is tapered. In a method of winding a connection portion insulating sheet wound around an outer circumferential surface portion of a cable insulator and an inner semiconductive layer in a state where a connection portion inner semiconductive layer is formed on an outer peripheral surface portion of each conductor connected by a conductor connecting tube,
A first insulating sheet portion having a sheet width changed corresponding to the width between the slopes in the valley portion is wound around the first valley portion between the inner semiconductive layer and the cable insulator to form an inner half. A first valley winding step of making the diameter substantially the same as the conductive layer, and a second valley formed by the inner semiconductive layer, the outer peripheral surface of the wound first insulating sheet, and the insulator slope of the power cable. A second valley winding step of winding a second insulating sheet portion whose sheet width changes in accordance with the width between the slopes of the insulators of both power cables so that the winding shape becomes substantially the same diameter as the insulator; , A third insulating sheet portion having a sheet width changed corresponding to a reinforcing insulating portion winding shape targeted at the connection portion, around the outer peripheral surface of the cable insulator, and the wound second insulating sheet. Reinforcement insulation section winding work to make the winding form the target reinforcement insulation section winding form An insulating sheet wrapped method of the connection portion of the insulated power cable, comprising a.

According to a fifth aspect of the present invention, the connecting portion insulating sheet is
A first insulating sheet portion, a second insulating sheet portion, and a third insulating sheet portion;
5. The method according to claim 4, wherein the insulating sheet portion is formed as a continuous integrated sheet.

The inventor of the present invention has made various studies to improve in-situ workability in connection of an insulated power cable such as a crosslinked polyethylene insulated power cable. According to the invention of claims 1 and 4, When embedding the connection reinforcement insulating layer by winding the insulation sheet, to emphasize on-site workability, the connection insulation sheet to be wound has a sheet width based on the sheet thickness, the interval between the winding parts, and the target winding shape. Changes along the sheet winding direction, and the winding shape is targeted.

As described above, if the insulating sheet is wound around the connection portion, the necessary shape and cross-sectional area of the reinforcing insulating layer can be obtained as it is. Become

Further, if the insulating sheet is wound around the connection portion, the sheet winding operation can be completed naturally without moving the winding position of the insulating sheet in the cable axis direction. Therefore, as in the case of using an insulating tape of the same width, the winding sheet can be wound around the required portion without any gap without spontaneous steps by simply winding the winding position without moving the winding position in the axial direction. it can. Therefore, the insulating sheet is easily brought into close contact at the time of winding, and the air entrainment amount is constant, so that there is no variation in quality due to the skill of the winder.

Further, if the insulating sheet is preferably formed as a continuous integrated sheet as in claim 2 or 5, continuous winding can be easily performed, and workability is further improved. .

Preferably, the insulating sheet is a non-cross-linked or semi-cross-linked polyolefin layer such as an EP rubber or a polyethylene containing a cross-linking agent by taking advantage of the above-mentioned GPP joint. It is configured as a single unit or configured to use a sheet containing an uncrosslinked EP rubber tape. For example, the insulating sheet is made of a crosslinked EP rubber layer and an uncrosslinked EP containing a crosslinking agent.
This is a two-layer insulating sheet for molding, which is bonded to a rubber layer. The insulating sheet is a mold insulating sheet having a three-layer structure in which an uncrosslinked EP rubber layer containing a crosslinking agent is attached to both sides of a crosslinked EP rubber layer.

Further, the insulating sheet is a two-layer in which a non-crosslinked or semi-crosslinked or crosslinked polyolefin layer such as non-crosslinked or semi-crosslinked or crosslinked polyethylene is bonded to an uncrosslinked EP rubber layer containing a crosslinking agent. It is a mold insulating sheet having a structure. The insulating sheet has a three-layer structure in which a non-cross-linked EP rubber layer containing a cross-linking agent is attached to both surfaces of a non-cross-linked, semi-cross-linked, or cross-linked polyolefin layer such as non-cross-linked or semi-cross-linked or cross-linked polyethylene. It is an insulating sheet for molding.

According to the third aspect of the present invention, the unmolded EP rubber sheet containing a crosslinking agent can be used to mold the insulating layer and the external semiconductive layer at the same time. G in workability when compared
This is to solve the disadvantage of the PP joint. In addition, the connection part according to the present invention can obtain more stable electric performance than the tape type joint adopted in the 66 to 77 kV class, and therefore can be sufficiently applied to the 154 kV class.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 3 are explanatory views of a connection portion A of a crosslinked polyethylene insulated power cable according to an embodiment of the present invention, and are shown according to a connection process.

As shown in FIG. 1, a crosslinked polyethylene insulated power cable 1, 1 whose ends are connected to each other has a cable conductor 2, 2 at the center, and a cable conductor 2, 2 at the outer periphery of the cable conductor 2, 2. Internal semiconductive layers 3 and 3, a cable insulator (insulating layer) 4 made of cross-linked polyethylene, a cable external semiconductive layer 5, and a cable metal shielding layer 6 are sequentially provided.
Further, the outer peripheral portions of the shielding layers 6, 6 are protected by cable sheaths 7, 7.

At each connection end 1a, 1a of the crosslinked polyethylene insulated power cable 1, 1 at the connection portion A, the respective cable conductors 2, 2 are exposed, and the cable outer semiconductive layers 5, 5 are stripped off. After finishing (pencilling) the wires 4 and 4 into a pencil shape, the cable conductors 2 and 2 are compression-connected to each other by the conductor connection tube 8. A semiconductive shrinkable tube is placed over the conductor connecting portion composed of the conductor connecting tube 8 and the exposed portion of the conductors 2 and 2, thereby forming a semiconductive layer 9 inside the connecting portion.

Next, a molding insulating sheet 10 including an uncrosslinked layer is wound between the cable outer semiconductive layers 5 and 5 at the two connection ends 1a and 1a while rotating in the axial direction. In this case, the insulating sheet 10 is mainly wound around a reel and manually wound, but can also be wound mechanically. The insulating sheet 10 to be wound has a sheet width that changes along the sheet winding direction and a desired winding shape based on the sheet thickness, the interval between the winding portions, and the target winding shape. A preferred example and a winding state of the insulating sheet 10 will be described later in detail with reference to FIGS.

By winding the insulating sheet for molding 10 as described above, an uncrosslinked reinforcing insulating layer (winding layer for insulating sheet for molding 10) 12 is formed at the connection portion as shown in FIG. Then, a semiconductive shrinkable tube or the like is covered to form a connection part external semiconductive layer 13.

As shown in FIG. 3, the uncrosslinked connection portion A formed by the above-described procedure has a pressure vessel (crosslinking mold) 15 with a heater 14 (however, the heater and the pressure vessel include a separate type). ), And the gas injection port 15 is maintained while the airtightness of the pressure vessel 15 is maintained by the gas seal portion 16.
a, a gas such as N ₂ is injected into the container 15 from the a, and the heater 14 is energized in a pressurized (3 to 15 kgf / cm ² ) range, thereby heating the insulating sheet 10 at the connection portion A (15).
(Temperature range of 0 to 300 ° C.) to cause a crosslinking reaction in the uncrosslinked layer to mold.

Next, a preferred example of the mold insulating sheet 10 and a procedure for winding the same will be described in detail. First, as shown in FIG. 4, in which winding the first insulation sheet 10 ₁ in the first valley portion 17 between the connecting portion inner semiconducting layer 9 and the cable insulation 4. Insulating sheet 10 ₁ in the first, the
A slope (a sheet width SL ₁ corresponding to the width L ₁ between the slope 17 a on the inner semiconductive layer 9 side and the slope 17 b on the cable insulator 4 side) that changes according to the winding amount of the sheet 10 ₁ in the valley portion 17.
, And has a substantially trapezoidal shape in plan view with a narrow tip and a wide tail. At the same time, as shown in FIG. 5, the winding shape of the _first insulating sheet 101 becomes a cylindrical shape on the outer peripheral surface having substantially the same diameter as the semiconductive layer 9 inside the connection portion.

[0033] Then, as shown in FIG. 6, the second valley portion formed between the first insulator 4 slope 4a of the outer peripheral surface and the power cable 1 of the insulation sheet 10 ₁ wound and inner semiconducting layer 9 18, is intended to wind a second insulating sheet 10 _2. The second insulating sheet 10 _2, there is the slope 4a of the insulator 4 of the two power cables 1,1, so as to correspond to the width L ₂ between 4a is changing the seat width SL _2, the tail from the tip The end has a slightly wide, substantially trapezoidal shape in plan view. At the same time, as shown in FIG. 7, the winding shape of the _second insulating sheet 102 becomes a cylindrical shape on the outer peripheral surface having substantially the same diameter as the insulator 4.

[0034] Then, as shown in FIG. 8, winding the second insulating third to the outer circumferential surface of the seat 10 _{and second} insulating sheet 10 ₃ is the cable insulation 4, and wound. The third insulation sheet ₁₀₃ is a one that is changing the seat width SL ₃ in response to winding shape of the reinforcing insulation layer 12 is targeted at the junction A, as Filter toward the tail end from the distal end It has a substantially trapezoidal shape in plan view that becomes narrower. Then, as shown in FIG. 9, the third insulating sheet 10
The winding shape of No. ₃ is a winding shape of the reinforcing insulating layer 12, and is a thread winding shape in which a central portion has a large diameter and becomes thin left and right. Then, on the surface of the reinforcing insulating layer 12, as shown in FIGS.
The connection portion external semiconductive layer 13 is covered and molded.

In the above-described embodiment, as described above, the first insulating sheet 10 ₁ , the second insulating sheet 10 ₂ , and the third insulating sheet 10 ₃ are used separately. However, the present invention is not limited to the case where the insulating sheets are separated from each other. As in the second embodiment shown in FIG. integrated Te to be able to form an insulating sheet 10 _0. Then, the winding shape after the winding is the target reinforcing insulating layer 12 as shown in FIG. According to the second embodiment, when the insulating sheet 10 is wound, continuous winding can be performed with one reel without replacing and winding the sheet one by one, so that the work is facilitated and the workability is further improved.

As shown in FIG. 12A, the insulating sheet 10 for a mold including an uncrosslinked layer has a tape thickness of less than 0.8 mm and a crosslinked EP rubber layer 10a. And a non-crosslinked EP rubber layer 10b containing a crosslinker bonded (laminated) to a mold insulating sheet 10A having a two-layer structure. FIG.
As shown in (b), the tape thickness is less than 0.8 mm, and a three-layer structure in which uncrosslinked EP rubber layers 10b and 10b containing a crosslinking agent are attached to both surfaces of the crosslinked EP rubber layer 10a. The molding insulating sheet 10B can be used.

As shown in FIG. 13A, the insulating sheet for molding 10 has a tape thickness of less than 0.8 mm and is made of non-crosslinked, semi-crosslinked, or crosslinked polyethylene. Cross-linked or semi-cross-linked or cross-linked polyolefin layer 10c and uncross-linked EP rubber layer 1 containing a cross-linking agent
0b and a two-layered molded insulating sheet 1
0C can be used. Further, as shown in FIG. 13B, the insulating sheet for molding 10 has a tape thickness of 0.1 mm.
An uncrosslinked EP rubber layer 10b containing a crosslinking agent is attached to both sides of a noncrosslinked, semicrosslinked, or crosslinked polyolefin layer 10c that is less than 8 mm and is noncrosslinked, semicrosslinked, or crosslinked polyethylene. A mold insulating sheet 10D having a three-layer structure can be used.

Before the heating molding, the reinforcing insulating layer 12
In the insulating sheet 10, a crosslinked EP rubber layer 10a, a non-crosslinked polyolefin layer 10c such as a non-crosslinked layer, and an uncrosslinked layer 10b are flexible, and the shapes of the valleys 16 and 17 and the winding shape of the target reinforcing insulating layer 12 are provided. Since the width has changed in conformity with
The insulating sheet 10 can be easily and uniformly wound. For this reason, the outer appearance of the rolled shape of the insulating sheet 10 can be made substantially flat. That is, for example, as shown in FIG. 9, the cylindrical portion 12 a on the outer surface of the reinforcing insulating layer 12 is flush with the outer surface of the insulating sheet 10. Even if there are slight irregularities in the portions 12b, 12b where the diameter is gradually reduced on the left and right sides of the reinforcing insulating layer 12, the irregularities can be formed as far as the connection portion external semiconductive layer 13 can be covered. Therefore, the connecting portion external semiconductive layer 13 can be attached before the heat molding, and the shaping work after the molding is not required as in the case of the GPP joint.

After the heat molding, the irregularities become dull and the outer surface becomes smooth, so that the molding can be performed in a state in which the outer semiconductive layer 13 on the connecting portion is sufficiently adhered to the outer surface.

The insulating sheet according to the present invention includes, of course, an uncrosslinked or semicrosslinked EP rubber containing a crosslinking agent,
Those formed of a single layer of a polyolefin such as polyethylene can also be used.

[0041]

As described above, according to the present invention, in the connection of the insulated power cable, the work time for forming the reinforcing insulating layer can be shortened to improve the on-site workability, and the variation in quality due to the skill of the winder can be improved. In addition, the insulating layer of the uncrosslinked EP rubber tape containing the crosslinking agent and the external semiconductive layer can be molded at a time.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a connecting portion of a crosslinked polyethylene insulated power cable according to an embodiment of the present invention, which is a cross-sectional view illustrating a connecting process until a molding insulating sheet is attached.

FIG. 2 is a cross-sectional view illustrating a state in which an external semiconductive layer is provided after winding a molding insulating sheet in a connection portion.

FIG. 3 is a cross-sectional view illustrating a heating mold under pressure of a connecting portion in FIG. 2;

FIG. 4 is an explanatory view of a preferred example of the insulating sheet, and is an explanatory view of a first insulating sheet and a winding state thereof.

FIG. 5 is a cross-sectional view illustrating an example of a winding shape of a first insulating sheet.

FIG. 6 is an explanatory diagram of a second insulating sheet and a winding state thereof.

FIG. 7 is a cross-sectional view illustrating an example of a roll shape of a second insulating sheet.

FIG. 8 is an explanatory diagram of a third insulating sheet and a wound state.

FIG. 9 is a cross-sectional view illustrating an example of a winding shape of a third insulating sheet.

FIG. 10 is an explanatory diagram of a continuously integrated insulating sheet and a wound state according to a second embodiment.

FIG. 11 is a cross-sectional view showing an example of a winding shape of the insulating sheet of FIG.

FIGS. 12A and 12B are cross-sectional views illustrating an example of a molding insulating sheet. FIG. 12A illustrates an example of two layers, and FIG. 12B illustrates an example of three layers.

FIGS. 13A and 13B are cross-sectional views illustrating another example of a molding insulating sheet, wherein FIG. 13A shows an example of two layers, and FIG. 13B shows an example of three layers.

FIG. 14 is an explanatory sectional view of a general connecting portion.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Crosslinked polyethylene insulated power cable 1a Connection end part of heated polyethylene insulated power cable 2 Cable conductor 4 Cable insulator 5 Cable outer semiconductive layer 8 Conductor connection pipe 9 Connecting part inner semiconductive layer 10 Insulating sheet for molding 10 ₁ to 10 ₃ the first to third insulating sheet 10 ₀ continuously integral insulating sheet 10A~10D insulating sheet 10a crosslinked EP rubber layer 10b crosslinking agent containing uncrosslinked EP rubber layer 10c uncrosslinked or semi crosslinked or crosslinked Polyolefin layer 12 Reinforced insulating layer 13 External semiconductive layer at connection portion 14 Heater 15 Pressure vessel 17 First valley 18 Second valley SL _{1 to} SL ₃ Width of insulating sheet

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuichi Mitsuyama 42-1, Shintomi, Futtsu-shi, Chiba Fujikura Futtsu Plant (56) References JP-A-57-129112 (JP, A) JP-A-8 JP-A-70527 (JP, A) JP-A-50-31387 (JP, A) JP-A-2-65614 (JP, A) JP-A-3-243109 (JP, A) JP-B-54-15631 (JP, B2) (58) Fields surveyed (Int. Cl. ⁶ , DB name) H02G 15/00-15/196

Claims (5)

(57) [Claims] 1. A connecting portion for connecting insulated power cables, wherein conductors of both power cables to be connected are exposed,
Strip the outer semiconductive layer, taper the cable insulator, connect the conductors with a conductor connection pipe, but form the inner semiconductive layer at the outer peripheral surface of the cable insulator. In the connecting part insulating sheet wound around the outer peripheral surface of the layer, the connecting part insulating sheet has a sheet width that changes along the sheet winding direction based on the sheet thickness, the interval between the winding portions, and the target winding shape, and Wherein the connection insulation sheet is wrapped around a first valley between the inner semiconductive layer and the cable insulator, the width being between the slopes at the valley. A first insulating sheet portion correspondingly changing the sheet width and having a winding shape substantially the same diameter as the inner semiconductive layer, an outer peripheral surface of the inner semiconductive layer and the wound first insulating sheet portion, and a power cable. Second forming at the insulator slope
A second insulating sheet portion in which the sheet width is changed corresponding to the width between the slopes of the insulators of both power cables and the winding form is substantially the same diameter as the insulator, a cable insulator; And a third insulating sheet portion which is wound around the outer peripheral surface of the wound second insulating sheet portion and has a sheet width changed corresponding to a reinforcing insulating portion winding shape targeted at the connection portion. An insulating sheet for a connection portion of an insulated power cable, characterized in that: 2. The connecting part insulating sheet according to claim 1, wherein the first insulating sheet part, the second insulating sheet part, and the third insulating sheet part are formed as a continuous integrated sheet. Item 2. An insulating sheet for a connecting portion of the insulated power cable according to item 1. 3. The connecting portion insulating sheet is formed of an uncrosslinked or semicrosslinked EP rubber containing a crosslinking agent, a polyolefin layer such as polyethylene alone, or a crosslinked EP rubber layer or a non-crosslinked EP rubber layer. Non-crosslinked, such as crosslinked, semi-crosslinked, or crosslinked polyethylene,
Or a semi-cross-linked or cross-linked polyolefin layer having a layer structure in which an uncross-linked EP rubber layer containing a cross-linking agent is attached to at least one surface of the cross-linked polyolefin layer, and molded after winding. 3. An insulating sheet for a connection portion of the insulated power cable according to 2. 4. A connecting portion for connecting insulated power cables, wherein conductors of both power cables to be connected are exposed,
Strip the outer semiconductive layer, taper the cable insulator, connect the conductors with a conductor connection pipe, but form the inner semiconductive layer at the outer peripheral surface of the cable insulator. In a method of winding a connection insulating sheet wound around an outer peripheral surface of a layer, a sheet width is changed in a first valley between an inner semiconductive layer and a cable insulator in accordance with a width between slopes in the valley. A first valley winding step of winding the first insulating sheet portion so that the winding shape is substantially the same diameter as the inner semiconductive layer; and an outer peripheral surface of the inner semiconductive layer and the wound first insulating sheet portion. The second formed by the insulator slope of the power cable
Is wound around a second insulating sheet portion whose sheet width changes in accordance with the width between the slopes of the insulators of the two power cables, so that the winding shape becomes substantially the same diameter as the insulator. Part winding step, a third insulator having a sheet width changed on the outer circumferential surface of the cable insulator and the wound second insulating sheet part in accordance with a reinforcing insulating part winding form targeted at the connection part. A method for winding an insulating sheet around a connection portion of an insulated power cable, comprising a step of winding a reinforcing insulating portion to wind a sheet portion into a target reinforcing insulating portion winding shape. 5. The connection part insulating sheet is formed as an integrated sheet in which a first insulating sheet part, a second insulating sheet part, and a third insulating sheet part are continuous. Item 5. The method for winding an insulating sheet around a connection portion of an insulated power cable according to Item 4.