KR20170084841A - hydrocarbon fire protection cable - Google Patents

Abstract

A high fire resistance cable is disclosed. According to the high-refractory cable according to the present invention, it is possible to exhibit the fireproof performance satisfying the international standard even in the case of a high-temperature fire caused by a hydrocarbon-based compound constituting the main component of petroleum and coal tar, By allowing the insulating layer to perform its insulation function for a long period of time, it is possible to further maintain the transmission power of the cable, and by delaying the time of the flame spreading, it is possible to secure the time required to evacuate people or place an appropriate fire extinguishing means have.
Further, it is possible to provide a high-refractory cable capable of improving workability by reducing the outer diameter and weight while ensuring high refractory performance and ensuring bending performance.

Description

A high fire resistance cable {hydrocarbon fire protection cable}

The present invention relates to a high-refractory cable, and more particularly, to a refractory cable capable of exhibiting refractory performance that meets international standards at the time of occurrence of a fire at a high temperature, reducing the outer diameter and weight, Refractory cable.

In recent years, a major issue in the cable manufacturing industry has been to improve cable behavior and performance in extreme temperature conditions, particularly in the face of fire. For safety, it is essential to delay the spread of flames and to maximize the ability of the cables to withstand flames.

Improving the fire-resistance of the cables will allow the cable to continue to consume more power in the event of a fire and delay the time it takes to fire to ensure the time required to evacuate people or deploy appropriate fire extinguishing equipment. .

The demand for refractory characteristics is gradually increasing. Especially, cable products used for oil drilling installations installed on the sea or oil / marine plants such as land refinery facilities require high fire resistance characteristics.

The reason for this is that when a fire occurs due to a hydrocarbon compound which is a main component of petroleum and coal tar, it generates heat at a higher temperature than usual. In general, it is at a high temperature of 830 ° C to 1100 ° C, It can go up to 1300 ° C.

In such a plant, there is a need for a cable for maintenance of the emergency equipment of core equipment, fire alarm, sprinkler, etc. for the operation and maintenance of fire fighting / disaster prevention system for a minimum period of time to evacuate and evacuate personnel under high temperature environment.

In the past, refractory cables have been mainly used for low-pressure applications. However, as disaster / fire prevention has become a major issue in recent years, there is a growing need for medium- and high-voltage fireproof cables.

Here, medium- and high-voltage cables generally refer to MVs of medium voltage or HV class (high voltage) of 6 kV or more, and medium- and high-voltage cables are collectively referred to as high-voltage cables.

For ordinary cables other than refractory, low voltage cables of 3 kV or less are sufficient for satisfying electrical characteristics with only one layer of insulation on the conductors. In the case of medium and high voltage cables, 'conductors - internal semiconductors - The triple structure of Fig.

Here, the insulating layer serves to prevent the current from flowing out of the cable by inserting the conductor inside from the outside, and the inner semiconductive layer serves to uniform the charge distribution on the surface of the conductor to relax the electric field concentration inside the cable, Thereby minimizing the deterioration of the insulator due to the ionization phenomenon. In addition, the outer semiconductive layer uniformizes electrical stress in the insulator and minimizes external corona.

When a voltage of 6 kV or more is applied, a tree is generated in the insulator, and the value of partial discharge (PD), which is one of important electrical characteristics, increases and the probability of progressive dielectric breakdown is high. It is necessary to uniformize electric field distribution and electric stress to satisfy partial discharge characteristics and to minimize dielectric breakdown.

International standards such as IEC 60331-21 (750 ° C for 90 minutes), BS 6387 (950 degrees for 20 minutes) and NEK606 (1100 degrees for 30 minutes to 60 minutes) have been established for these high-pressure fireproof cable products. have.

In the severe conditions of NEK606-HCF (Hydro-Carbon Fire protection), it is difficult to meet the requirement for the refractory layer and silicone resin insulation using the existing MICA tape.

Accordingly, there is a need for a high-refractory cable capable of exhibiting fire resistance performance that meets international standards when a fire occurs at a high temperature.

The embodiments of the present invention are intended to exhibit fire resistance performance that meets international standards even in the event of a high temperature fire caused by a hydrocarbon compound which is a main component of petroleum and coal tar.

In addition, in case of a fire, the thermal insulation of the thermal insulation layer secures sufficient thermal insulation performance so that the insulating layer performs the insulation function for a long time, thereby further continuing the power transmission of the cable.

In addition, by delaying the time of flame spread, it is intended to secure the time necessary to evacuate the person or place the appropriate fire extinguishing means.

It is also intended to provide a high-refractory cable capable of improving workability by reducing bending performance while reducing the outer diameter and weight while exhibiting a high level of refractory performance.

According to an aspect of the present invention, there is provided a semiconductor device comprising: a conductor; An insulating layer formed outside the conductor; A bedding layer formed outside the insulating layer; An inner sheath formed outside the bedding layer; A first heat shield layer formed outside the inner sheath layer and having an adiabatic performance in case of fire; And a second thermal barrier layer formed outside the first thermal barrier layer, wherein the first thermal barrier layer comprises at least one gap formed along the inner circumference of the second thermal barrier layer, Cables may be provided.

The first heat shield layer may have a thickness of 6 mm to 14 mm.

The material of the first and second thermal insulation layers may be rubber, EVA (Ethylene Vinyl Acetate) foam, or XLPO (Crosslinked Polyolefin).

The first thermal barrier layer and the second thermal barrier layer may further comprise silica or mica powder.

The bed layer is made of the same material as the first thermal barrier layer, but may include crosslinking characteristics.

Wherein the gap comprises a plurality of first gaps formed to have a constant thickness along the inner circumference of the second thermal barrier layer and at least one second gaps formed to have a thickness less than the first gaps .

The number of the first gap and the number of the second gap may be 2: 1.

The thickness of the first gap may be between 2 mm and 5 mm.

The thickness of the second gap may be 0.5 mm to 2 mm.

According to another aspect of the present invention, there is provided a semiconductor device comprising: a conductor; An insulating layer formed outside the conductor; A bedding layer formed outside the insulating layer; An inner sheath formed outside the bedding layer; And a first heat shield layer formed outside the inner sheath layer and having an adiabatic performance in case of fire; And a second thermal barrier layer formed outside the first thermal barrier layer, wherein the first thermal barrier layer is provided at regular intervals along the inner circumference of the second thermal barrier layer and extends toward the second thermal barrier layer A plurality of first teeth formed on the first heat shield layer and contacting the second heat shield layer; a second saw tooth extending between the first saw teeth toward the second heat shield layer and forming a certain gap between the second heat shield layer and the second heat shield layer; A high refractory cable can be provided.

The high refractory cable according to the present invention may further comprise a heat insulating tape wound around the second thermal insulation layer.

The heat insulating tape may be any one of a mica tape, a silica tape, and a glass tape.

One or two pieces of the heat insulating tape may be wound.

When one piece of the heat insulating tape is wound, the overlapping ratio of the heat insulating tape to the width may be 5% to 50%.

The high refractory cable according to the present invention may further comprise an outermost sheath layer formed outside the heat insulating tape.

The high refractory cable according to the present invention may further comprise a foam layer formed between the inner sheath layer and the first heat shielding layer.

The foam layer may be formed of any one of polypropylene (PP), nonwoven fabric, and nylon tape.

The high-refractory cable according to the present invention may further include an inner semiconductive layer provided between the conductor and the insulating layer, and an outer semiconductive layer provided between the insulating layer and the beding layer.

The high refractory cable according to the present invention may further comprise a braided layer provided between the bedding layer and the inner sheath layer.

The embodiments of the present invention can exert fire resistance performance that meets international standards even in case of a high temperature fire due to a hydrocarbon compound which is a main component of petroleum and coal tar.

In addition, when a fire occurs, the thermal insulation of the thermal insulation layer ensures a sufficient thermal insulation performance, so that the insulating layer performs the insulation function for a long period of time, thereby further continuing the power transmission of the cable.

In addition, by delaying the time of the flame spreading, it is possible to secure the time required to evacuate the person or place the appropriate fire extinguishing means.

Further, it is possible to provide a high-refractory cable capable of improving workability by reducing the outer diameter and weight while ensuring high refractory performance and ensuring bending performance.

1 is an exploded perspective view of a high-refractory cable according to an embodiment of the present invention.
2 is a cross-sectional view of a high refractory cable according to an embodiment of the present invention
3 is a cross-sectional view of a high-refractory cable according to another embodiment of the present invention
FIG. 4 is a graph comparing the heat transfer analysis results of a high-refractory cable according to the present invention and a cable having an existing structure
5 is a graph comparing insulation temperature changes with time of a high-refractory cable according to the present invention and a conventional cable

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals designate like elements throughout the specification.

FIG. 1 is an exploded perspective view of a high-refractory cable according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a high-refractory cable according to an embodiment of the present invention.

Referring to FIGS. 1 and 2, a high-refractory cable according to an embodiment of the present invention includes a conductor 110, an insulation layer 130 formed outside the conductor 110, An inner sheath layer 176 formed on the outer side of the bedding layer 172 and an inner sheath layer 176 formed on the outer side of the inner sheath layer 176, (180) and a second thermal barrier layer (186) formed outside the first thermal barrier layer (180).

The conductor 110 may be a Class 2 or Class 5 conductor satisfying the IEC 60228 standard. The inner semiconductive layer formed on the outer side of the conductor 110 is formed by winding the semiconductive tape 120 or forming a semi-conductive extruded layer 122 by extruding the semiconductive compound, , And 122 may be formed.

In this embodiment, the inner semiconductive layer is composed of the composite layers 120 and 122 by simultaneously applying the semi-conductive tape 120 and the semi-conductive extruded layer 122 as shown in FIGS.

The inner semiconductive layer uniformly distributes the charge on the surface of the conductor so as to alleviate the electric field concentration inside the cable and to fill the gaps between the conductors 110 and the insulating layer 130 to be described later, It can play a role of minimizing deterioration.

The insulating layer 130 is made of a material having insulating and impact resistance properties. The insulating layer 130 covers and protects the conductor 110 and insulates the conductor 110 from the outside, thereby preventing current from flowing out of the cable. . The insulating layer 130 may be formed of a material selected from the group consisting of silicone rubber, cross-linked polyethylene (XLPE), crosslinked polyolefin (XLPO), ethylene-propylene rubber (EPR) A polymer such as high ethylene-propylene rubber (EPR), polyvinyl chloride (PVC), and the like, and a mixture thereof.

The outer semiconductive layer 140 formed outside the insulating layer 130 may be formed by extruding a semiconductive compound or by winding a semiconductive tape in the same manner as the inner semiconductive layer, . The outer semiconductive layer 140 serves to uniformize electrical stress in the insulating layer 130 and to minimize external corona.

The shielding layer 150 formed outside the outer semiconductive layer 140 may be formed of metal tape or metal braid using a material such as copper, aluminum, a copper alloy, or an aluminum alloy. The shielding layer 150 must be in contact with the outer semiconductive layer 140 because if the shielding layer 150 and the outer semiconductive layer 150 are not in contact with each other, to be.

However, the present invention is not limited thereto, and may be a single-phase structure, a pair, or a quad structure in which only one conductor 110 is provided. May be applied.

In this embodiment, the three conductors 110 are formed as a joint structure, and a joint tape (not shown) may be wound around the conductors 110 to prevent the joint structure from being released.

A bedding layer 172 may be provided in a form of a solid-extruded structure outside the joint structure. The bedding layer 172 may be made of the same material as that of the first thermal insulation layer 180, which will be described later.

A braided layer 174 is formed outside the bedding layer 172. The braided layer 174 may be formed of a metal material such as copper, aluminum, iron, a copper alloy, or an aluminum alloy, and may be formed of a metal braid, a metal tape, or a metal wire.

An inner sheath layer 176 may be formed outside the braided layer 174. The inner sheath layer 176 may be made of a halogen-free polyvinyl chloride (PVC), a polychloroprene rubber (CR), a chlorosulfonated polyethylene (CHO), or the like. (CSPE), chlorinated polyethylene (CPE), ethylene vinyl acetate (EVA), or mixtures thereof, and crosslinking properties may be added as needed.

A first thermal barrier layer 180 is formed outside the inner sheath layer 176 and a second thermal barrier layer 186 is formed outside the first thermal barrier layer 180. The first thermal barrier layer 180 and the second thermal barrier layer 186 are independently formed and the first thermal barrier layer 180 is formed through an extrusion process. After cooling, the second thermal barrier layer 180 is extruded, A single layer 186 can be formed.

At this time, the first thermal barrier layer 180 may include a gap 182a formed along at least one inner circumference of the second thermal barrier layer 186. The gap 182a may be formed to have a constant thickness at regular intervals along the circumferential direction. An air layer may be formed between the first and second heat fault layers 180 and 186 to secure the heat insulation performance .

Here, to form the gap 182a on the first thermal barrier layer 180, a tooth 184a may be formed when the first thermal barrier layer 180 is extruded.

The teeth 184a are spaced along the inner circumference of the second thermal barrier layer 186 and extend toward the second thermal barrier layer 186 to contact the second thermal barrier layer 186. The clearance 182a is formed between the teeth 184a. That is, a space formed between the teeth 184a and the inner side surface of the second heat fault layer 186 forms the gap 182a.

As described above, when the first thermal insulation layer 180 is extruded, a plurality of teeth 184a are extruded so as to extend outward, and after the cooling, the second thermal insulation layer 186 is further extruded. The gap 182a can be formed to have an exact shape and thickness as intended.

The second thermal barrier layer 186 may exert its own heat insulation performance but may be further extruded outside the first thermal barrier layer 180 on which the teeth 184a are formed to form the gap 182a in an accurate shape It also plays a role.

Meanwhile, the thickness of the entire first fault layer 180 may be 6 mm to 14 mm. When the thickness of the first thermal insulation layer 180 is less than 6 mm, the heat insulation performance is remarkably reduced and the required fire resistance performance is not satisfied. If the thickness of the first thermal insulation layer 180 is larger than 14 mm, the heat insulation performance is secured. However, since the outer diameter and weight of the entire cable are increased, it is difficult to install the cable in the structure due to lowering of workability and lowering of bendability. There is a problem to lose. Therefore, the thickness of the first thermal insulation layer 180 is preferably 6 mm to 14 mm.

The material of the first and second thermal insulation layers 180 and 186 may be rubber, EVA (Ethylene Vinyl Acetate) foam, or XLPO (Crosslinked Polyolefin) to exhibit thermal insulation performance. Further, by further adding a flame retardant material such as silica or mica powder thereto, the thermal performance can be further improved.

As described above, the bedding layer 172 may be formed of the same material as the first thermal insulation layer 180 to improve the heat insulation performance of the entire cable. That is, it is made of any one material of rubber, EVA (Ethylene Vinyl Acetate) foam or XLPO (Crosslinked Polyolefin) like the first thermal insulation layer 180, and the above-mentioned flame retardant material may further be included. However, in order to slow the collapse of the bedding layer 172 during a fire, a crosslinking property may be added to the base material.

Meanwhile, the high-refractory cable according to the present invention may further include a heat insulating tape 189 wound on the outside of the second heat fault layer 186. That is, a heat insulating tape 189 having a heat insulating performance is further applied to the outside of the second heat fault layer 182. The heat insulating tape 189 may be a mica tape, a silica tape, or a glass tape may be applied.

When one piece of the heat insulating tape 189 is wound, the overlapping ratio of the heat insulating tape 189 to the width of the heat insulating tape 189 is set to 5% to 50% .

Here, the overlap ratio can be used synonymously with the wrap ratio or the overlap ratio of the heat insulating tape 189. When the one heat insulating tape 189 is wound with a half overlap ratio, the overlap ratio is 50% The same effect as in the case of winding the heat insulating tape in the non-wrap state, that is, in the case where the heat insulating tape is wound at the overlapping ratio of 0%.

The outermost sheath layer 190 is formed on the outer side of the heat insulating tape 189. The outermost sheath layer 190 may be made of polyvinyl chloride (PVC) having good heat resistance, Extrusion of polychloroprene rubber (CR), chlorosulfonated polyethylene (CSPE), chlorinated polyethylene (CPE), ethylene vinyl acetate (EVA) Layer type, can be added with crosslinking characteristics when necessary, and protects the cable from external impact or corrosion.

3 is a cross-sectional view of a high-refractory cable according to another embodiment of the present invention. Hereinafter, the same parts as those of the high-refractory cable shown in Figs. 1 and 2 will be omitted and the other parts will be mainly described.

The first thermal insulation layer 180 may include a first gap 182a formed to have a predetermined thickness along the inner circumference of the second thermal insulation layer 186 and a second gap 182a formed to extend from the first gap 182a And at least one second gap 182b formed to have a small thickness.

The first gap 182a plays a role of securing the main heat insulation performance by forming an air layer with a relatively large gap between the first thermal barrier layer 180 and the second thermal barrier layer 186, 2 gap 182b may serve to expand a heat insulating layer between the first gaps 182a.

In addition, the second gap 182b is formed at a small interval so as to abut the inner sheath layer 176 at the time of cable bending for installation, thereby supporting the load and dispersing the bending stress, The role can also be performed together.

As in the previous embodiment, the first thermal barrier layer 180 may be manufactured by extrusion, in order to form such a first gap 182a and a second gap 182b on the first thermal barrier layer 180 The first tooth 184a and the second tooth 184b can be formed when the first thermal insulation layer 180 is extruded.

The first cogs 184a are spaced along the inner circumference of the second thermal barrier layer 186 and extend toward the second thermal barrier layer 186 to contact the second thermal barrier layer 186 do.

The second toothed portion 184b is provided between the first toothed portions 184a and extends between the first toothed portions 184a toward the second thermal fault layer 186 and the second thermal fault layer 186 And a constant gap is formed between them.

It is preferable that the first teeth 184a and the second teeth 184b are provided so as to be symmetrical with respect to each other in order to alternately maintain the uniform distribution of the stresses and the roundness and the first teeth 184a and the second teeth 184b, And a gap formed between the second tooth 184b and the second thermal barrier layer 186 forms a second gap 182b.

Since the first teeth 184a and the second teeth 184b are alternately arranged symmetrically, the number of the first gap 182a and the second gap 182b may be 2: 1. That is, in the present embodiment, four first teeth 184a and second teeth 184b are provided, and a first gap 182a is formed between the first teeth 184a and the second teeth 184b, And four second gaps 182b are formed between the second tooth 184b and the second thermal barrier layer 186. [

The number of the first teeth 184a and the number of the second teeth 184b and the number of the first gap 182a and the second gap 182b are not limited to the above embodiments, It is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention.

As in the previous embodiment, the entire thickness of the first thermal insulation layer 180 may be 6 mm to 14 mm. The thickness of the first gap 182a may be in the range of 2 mm to 5 mm, and the thickness of the second gap 182b may be in the range of 0.5 mm to 2 mm.

The high refractory cable according to the present invention may further include a foam layer 188 formed between the inner sheath layer 176 and the first heat shield layer 180. The foam layer 188 may be formed of any one of polypropylene, nonwoven fabric, and nylon tape.

By forming the foam layer 188 having a heat shield effect inside the first thermal insulation layer 180, the overall heat insulation effect can be further improved.

Although the foam layer 188 is added only in the embodiment shown in FIG. 3, it is not limited thereto. It is needless to say that the foam layer 188 may be additionally provided in the embodiment shown in FIGS. 1 and 2 .

FIG. 4 is a view for comparing heat transfer analysis results of a high-refractory cable according to the present invention and a cable having a conventional structure, and FIG. 5 is a graph comparing the insulation temperature changes of a high- Graph.

As shown in FIG. 3 and FIG. 5, the actual fire resistance test of the high-refractory cable and the comparative example according to the embodiment of the present invention was performed.

Case 1 is a comparative example in which there is only one heat fault layer and no gap is formed on the heat fault layer. Case 2 has the same structure as that shown in Figs. 1 and 2, And a gap formed therein.

Case 2 according to the embodiment of the present invention differs from case 1 in that the temperature of the insulating layer 130 is extremely low to 329 캜 and is half the level of the case 1 while the refractory test is performed at 1100 캜 for 60 minutes, It can be confirmed that the performance is maintained.

That is, the high-refractory cable according to the embodiments of the present invention exhibits sufficient heat insulation performance even under the condition of NEK606-HCF (Hydro-Carbon Fire protection) at 1100 DEG C for 60 minutes so that the insulation layer 130 performs the insulation function The power of the cable can be maintained for a long time.

According to the high-refractory cable according to the embodiments of the present invention described so far, it is possible to exhibit the fireproof performance satisfying the international standard even in the case of a high-temperature fire caused by a hydrocarbon compound constituting the main component of petroleum and coal tar, By ensuring sufficient thermal insulation performance of the fault, the insulating layer can perform its insulation function for a long time to further maintain the electric power of the cable. By delaying the time of the flame spreading, people can be evacuated or an appropriate fire extinguishing means It is possible to secure the time required for the operation.

Further, it is possible to provide a high-refractory cable capable of improving workability by reducing the outer diameter and weight while ensuring high refractory performance and ensuring bending performance.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims. You can do it. It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

100: high refractory cable 110: conductor
130: insulating layer 172: bedding layer
174: braided layer 176: inner sheath layer
180: heat fault layer 182a: first clearance
182b: second gap 184a: first tooth
184b: second saw tooth 189: insulating tape
190: Outer sheath layer

Claims (19)

Conductor;
An insulating layer formed outside the conductor;
A bedding layer formed outside the insulating layer;
An inner sheath formed outside the bedding layer;
A first heat shield layer formed outside the inner sheath layer and having an adiabatic performance in case of fire; And
And a second thermal barrier layer formed outside the first thermal barrier layer,
Wherein the first thermal insulation layer comprises a gap formed along at least one inner circumference of the second thermal insulation layer. The method according to claim 1,
Wherein the thickness of the first thermal insulation layer is 6 mm to 14 mm. The method according to claim 1,
Wherein the first and second heat shielding layers are made of rubber, EVA (Ethylene Vinyl Acetate) foam, or XLPO (Crosslinked Polyolefin). The method of claim 3, wherein
Wherein the first and second heat shielding layers further comprise silica or mica powder. 5. The method of claim 4,
Wherein the bed layer is made of the same material as the first thermal barrier layer, but includes crosslinking properties. The method according to claim 1,
The gap
A plurality of first gaps formed to have a constant thickness along the inner circumference of the second heat shield layer,
And at least one second gap formed to have a thickness smaller than the first gap. The method according to claim 6,
Wherein the first gap and the second gap number are 2: 1. The method according to claim 6,
And the thickness of the first gap is 2 mm to 5 mm. The method according to claim 6,
And the thickness of the second gap is 0.5 mm to 2 mm. Conductor;
An insulating layer formed outside the conductor;
A bedding layer formed outside the insulating layer;
An inner sheath formed outside the bedding layer; And
A first heat shield layer formed outside the inner sheath layer and having an adiabatic performance in case of fire; And
And a second thermal barrier layer formed outside the first thermal barrier layer,
Wherein the first railway fault layer
A plurality of first teeth formed at regular intervals along an inner circumference of the second heat shield layer and extended toward the second heat shield layer and in contact with the second heat shield layer;
And a second tooth extending from the first teeth toward the second thermal insulation layer and forming a gap between the first thermal insulation layer and the second thermal insulation layer. 11. The method according to any one of claims 1 to 10,
Further comprising a heat insulating tape wound around the outside of the second thermal insulation layer. 12. The method of claim 11,
Wherein the heat insulating tape is one of a mica tape, a silica tape, and a glass tape. 12. The method of claim 11,
Wherein one or two pieces of the heat insulating tape are wound. 14. The method of claim 13,
Wherein the overlapping width of the heat insulating tape is 5% to 50% when one piece of the heat insulating tape is wound. 12. The method of claim 11,
And an outermost sheath layer formed outside the heat insulating tape. 11. The method according to any one of claims 1 to 10,
Further comprising a foam layer formed between the inner sheath layer and the first heat shielding layer. 17. The method of claim 16,
Wherein the foam layer is made of any one of polypropylene (PP), nonwoven fabric, and nylon tape. 11. The method according to any one of claims 1 to 10,
An inner semiconductive layer provided between the conductor and the insulating layer,
And an outer semiconductive layer provided between the insulating layer and the beding layer. 11. The method according to any one of claims 1 to 10,
And a braided layer provided between the bedding layer and the inner sheath layer.

Images