JP2005176542A - Cable dry termination section - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cable dry termination section preventing degradation in mechanical and electrical characteristics even if an external force due to earthquake, wind or the like is applied for a long time, and improving long-term reliability. <P>SOLUTION: In this cable dry termination section made by providing a normal temperature contraction type polymer bush tube 10 having a shielding section 4 at an outer peripheral surface with multiple stages on the cable insulation body 2 of a cable end 1 in a rubber or plastic insulation cable, such as a CV cable (bridging polyethylene insulation cable), reinforcement core material 13 which is made by linear, bar, tube material such as steel material and FRP material is inserted in at least a range from a portion in which the polymer bush tube 10 is provided to a portion in which the cable end 1 is fixed in the cable conductor 2. A stress cone 5 and a high dielectric layer 11 with a dielectric constant which is higher than the one of the polymer bush tube 10 so as to be positioned at least in an inner layer portion of the bush tube 10 adjacent to the cone are respectively integrally formed on the base portion side of the polymer bush tube 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cable dry termination using a cold shrinkable polymer sleeve.

  As a terminal part of rubber or plastic insulating cable such as a CV cable (cross-linked polyethylene insulating cable), a cable dry terminal part using a normal temperature shrinkable polymer sleeve as shown in FIG. 5 has been proposed. This terminal portion is formed by providing a normal temperature shrinkable polymer sleeve 3 having a plurality of shade portions 4 on the outer peripheral surface on the cable insulator 2 of the cable end portion 1. The polymer sleeve 3 includes a room temperature shrinkable inner layer tube 3a formed of an elastic insulating mixture based on an insulating polymer material such as EPR and silicone rubber, and a base material of a polymer material such as EPR and silicone rubber. It has a two-layer structure with an outer layer tube 3b formed of an anti-tracking insulating mixture containing an anti-tracking material or the like as a filler. The cap portion 4 is integrally formed on the outer peripheral surface of the outer layer tube 3 b of the polymer sleeve 3. In addition, 5 is a semiconductive stress cone formed integrally on the base side of the polymer sleeve 3, 6 is a cable conductor, 7 is stepped off the cable end 1, and the cable conductor 2 is connected to the cable conductor 6. A terminal connected by pressure contact to the cable conductor lead-out portion 6a where the wire is exposed, and 8 is a waterproof tape wound around the terminal pressure contact portion 7a of the terminal 7 around the outer periphery of the outer tube 3b at the tip of the polymer sleeve 3 A waterproof protective layer 9 is an attachment body such as a device wall and a bracket plate for fixing the lower portion of the cable end 1 (see Patent Document 1). In addition, there has been proposed a similar cable dry-type terminal portion using a cold-shrink type single-layer polymer sleeve (not shown) (see Patent Document 2).

Japanese Patent Laid-Open No. 10-117425 (paragraph numbers 0054, 0069 to 0071, 0074 to 0075, 0094 to 0098 in FIG. 6) Japanese Patent Laid-Open No. 6-150985 (paragraph numbers 0012 to 0017 in FIGS. 1 to 3 in the Detailed Description of the Invention)

  The cable dry termination using such a cold-shrinkable polymer sleeve is unlikely to break down due to a ground fault compared to a cable wet termination in which insulating oil is filled in a highly rigid porcelain insulation sleeve. Even if this occurs, there is an advantage that the problem of environmental pollution due to the occurrence of fire due to ignition, fire spread or oil leakage is reduced. In addition, there is an advantage that it is small, inexpensive and excellent in workability as compared with a cable dry end portion reinforced with FRP or the like and using a highly temperature-shrinkable polymer sleeve having a large rigidity.

  However, such cable dry-type terminations are usually used by being fixed to the mounting body in an upright state, similar to those using cable wet-type terminations and emergency temperature shrinkable polymer sleeves. The shrinkable polymer sleeve is less rigid than the above-mentioned porcelain insulating sleeve and the emergency temperature shrinkable polymer sleeve, and is provided so as to be in close contact with the cable insulator 2 at the cable end 1. In addition, it is necessary to maintain the rigidity of the end portion with the cable conductor 6 and the cable insulator 2. For this reason, independence worsens compared with the said cable wet termination | terminus part etc. Therefore, if external forces due to earthquakes, winds, etc. are repeatedly applied to this cable dry termination for a long period of time, rolling, bending, etc. are likely to occur, and the mechanical characteristics of the termination and the electrical characteristics are reduced accordingly. Reliability may be impaired.

  The present invention was devised in view of the above, and a cable dry termination that can prevent deterioration of mechanical and electrical characteristics and improve long-term reliability even when an external force due to an earthquake, wind, etc. is applied over a long period of time. It is intended to provide.

  In order to achieve the above object, according to the first aspect of the present invention, a cold-shrinkable polymer sleeve having a plurality of shade portions on the outer peripheral surface is provided on the cable insulator at the cable end. In the cable dry-type terminal portion, the reinforcing core material is inserted over a range from at least a portion where the polymer sleeve is provided in the cable conductor to a portion where the cable end portion is fixed.

  According to a second aspect of the present invention, in the cable dry end portion according to the first aspect of the invention, the stress cone and at least the inner layer portion of the sleeve in the vicinity thereof are located on the base side of the polymer sleeve. And a high dielectric layer having a higher dielectric constant than that of the polymer sleeve.

  According to the cable dry termination portion of the present invention, since the rigidity of the cable conductor at the cable end portion is increased and the self-supporting property of the termination portion is improved, the cable dry termination portion has an earthquake over a long period of time. Even when an external force due to wind or the like is repeatedly applied, rolling, bending, and the like are less likely to occur. Accordingly, the mechanical and electrical characteristics of the terminal portion are not deteriorated, and long-term reliability can be improved.

  When the high dielectric layer is formed so as to be positioned at least in the inner layer portion of the sleeve in the vicinity of the stress cone, as in the cable dry end portion described in claim 2 of the present invention, the interval between the equipotential lines is narrow. Thus, the equipotential lines in the vicinity of the tip of the stress cone where the equipotential lines tend to concentrate are widened, so that the concentration of the electric field is alleviated, the withstand voltage characteristics can be improved, or the terminal portion can be downsized.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a cable dry termination according to the present invention. In addition, the same code | symbol is attached | subjected to the thing of the same structure as the conventional cable dry termination | terminus part.

  The cable dry-type terminal portion of this embodiment has a plurality of shade portions 4 on the outer peripheral surface on the cable insulator 2 of the cable end portion 1 of rubber or plastic insulated cable such as a CV cable (crosslinked polyethylene insulated cable). A cold-shrinkable polymer sleeve 10 is provided. The polymer sleeve 10 is a single layer structure formed by molding a cylindrical shape with an elastic insulating mixture based on an insulating polymer material such as ethylene propylene rubber, ethylene propylene diene rubber, chloroprene rubber, butyl rubber, and silicone rubber. The cap portion 4 made of the same material as the sleeve 10 is integrally molded on the outer peripheral surface thereof.

  Further, a cylindrical shape having a dielectric constant ε higher than that of the polymer cannula 10 is located on the base side of the polymer cannula 10 so as to be positioned at least in an inner layer portion of the semiconducting stress cone 5 and the cannula 10 in the vicinity thereof. The high dielectric layer 11 is formed by molding integrally with the sleeve 10 at the same time as molding. When the polymer sleeve 10 and the high dielectric layer 11 are formed using, for example, silicone rubber (dielectric constant ε is 2.7 to 4.2) as a base material, the high dielectric layer 11 is formed on a silicone rubber base material. A high dielectric constant particle such as carbon black, silicon carbide, titanium oxide, or barium titanate is blended as a filler so that the dielectric constant ε is 10 to 100. In the illustrated example, the high dielectric layer 11 is formed not only in the inner layer portion of the sleeve 10 but also in the end portion of the stress cone 5. The high dielectric layer 11 covers the cone 5 from the inner layer portion of the cannula 10 beyond the tip portion of the stress cone 5, or both the inner layer portion and the outer portion of the stress cone 5 spaced from the inner layer portion. You may make it form in.

  In this way, when the high dielectric layer 11 is formed so as to be located at least in the inner layer portion of the sleeve 10 in the vicinity of the stress cone 5, as shown in FIG. Since the interval between the equipotential lines 12 near the tips of the stress cones 5 where the wires 12 are likely to concentrate is widened, the concentration of the electric field is relaxed, the withstand voltage characteristics can be improved, or the terminal portion can be downsized. preferable.

  Further, as shown in FIGS. 1 and 2, the cable end 6 extends from the portion where the polymer sleeve 10 is provided at least along the longitudinal direction of the cable conductor 6 in the cable conductor 6 at the cable end 1, preferably at the center thereof. One to a plurality of reinforcing core members 13 (one in the illustrated example) are inserted and attached over a range up to a portion where the portion 1 is fixed to the attachment body 9. In the illustrated case, the end of the reinforcing core member 13 is inserted and attached so as to extend from the cable insulator 2 to the cable conductor lead-out portion 6a where the cable conductor 6 is exposed by stepping the cable end 1. Yes. Further, in the illustrated example, the end of the reinforcing core member 13 is up to a portion fixed to the attachment body 9, but it is inserted so as to extend beyond the attachment body 9 to an arbitrary position on the back side of the cable end 1. You may make it do.

  As the reinforcing core member 13, it is preferable to use one or a plurality of relatively rigid steel materials (including piano wire materials and stainless steel materials), FRP material wires (including twisted wires), rods, and pipe materials. Moreover, even if it is made of the same material as the cable conductor 6, it can be used as the reinforcing core member 13 if it is formed into a shape that is difficult to bend such as a tube or a bar. The reinforcing core member 13 is preferably inserted into the cable conductor 6 in the step of manufacturing the cable conductor 6 (twisting step). One or a plurality of reinforcing core members 13 may be inserted into the central portion of the cable conductor 6 and its peripheral portion, or one or a plurality of reinforcing core members 13 may be inserted only into the peripheral portion.

  Thus, by inserting the reinforcing core member 13 over the range from at least the portion where the polymer sleeve 10 is provided in the cable conductor 6 to the portion where the cable end 1 is fixed, the cable conductor 6 at the cable end 1 is inserted. This increases the rigidity of the end portion and improves the independence of the end portion. As a result, even if external forces due to earthquakes, winds, etc. are repeatedly applied to the installed cable dry termination for a long period of time, rolling, bending, etc. are less likely to occur, and the mechanical and electrical characteristics of the termination are not degraded. Can improve long-term reliability.

  Reference numeral 7 denotes a terminal connected to the cable conductor lead-out portion 6a exposed from the cable insulator 2 by stripping the cable end portion 1 at the terminal press-contact portion 7a, and 9 denotes a lower portion of the cable end portion 1. It is an attachment body such as a wall of a device and a bracket plate for fixing with an attachment member (not shown).

  When assembling the cable dry termination having the above-described configuration, it is performed as follows. First, in order to perform this work smoothly, a core member is provided so that a polymer sleeve 10 having a cap portion 4, a stress cone 5 and a high dielectric layer 11 can be easily provided on the cable insulator of the cable end portion 1 in advance. A cored polymer sleeve 14 is prepared in which the diameter of the core is expanded to a predetermined diameter by 15 (see FIG. 4). The core member 15 has a length longer than that of the polymer cannula 10 by spirally winding a polypropylene cord 15a having a substantially rectangular cross section having a thickness of about 5 mm and joining adjacent cords in a separable manner. Thus, it is formed in a cylindrical shape and can withstand the compressive force of the polymer cannula 10 whose diameter has been maintained. Then, one end (tip) of the string 15a constituting the core member 15 is pulled out from one side (left side in FIG. 4) of the core member 15 and passed through the core member 15, and the other side of the core member 15 (right side in FIG. 4). ) To extend outward from.

  Next, the cable end portion 1 in which the reinforcing core member 13 is inserted is stripped over a range from at least a portion where the polymer sleeve 10 is provided in the cable conductor 6 to a portion where the cable end portion 1 is fixed. The terminal 7 is pressed and connected to the cable conductor lead-out portion 6a exposed from the cable insulator 2, and the cable end 1 is subjected to terminal treatment.

  Next, as shown in FIG. 4, the terminal end of the cable end portion 1 terminated in the cored polymer sleeve 14 is protruded from the opposite side (right side in FIG. 4) of the sleeve 14. And placed at a predetermined position.

  Next, one end (tip) of the string 15a of the core member 15 is pulled in the direction of the arrow in FIG. 4, and the core member 15 is disassembled from one side (left side in FIG. 4) to the other side (right side in FIG. 4). Along with this, the polymer sleeve 10 is gradually restored and contracted from one side (left side in FIG. 4) to the other side (right side in FIG. 4). When the core member 15 is completely disassembled, the polymer cannula 10 is tightly adhered to the cable insulator 2 by the contracting force and at a predetermined surface pressure in an airtight manner so as to straddle the terminal pressure contact portion 7a of the terminal 7. Provided. In this way, the cable dry termination is assembled. If necessary, a waterproof protective layer (see FIG. 5) is wound around the outer periphery of the distal end portion of the polymer sleeve 10 provided on the cable insulator 2 so as to straddle the terminal pressure contact portion 7a of the terminal 7. (Not shown) may be formed.

  The terminal 7 may be connected to the cable conductor lead-out portion 6 a exposed from the cable insulator 2 after the polymer sleeve 10 is provided on the cable insulator 2. In this way, it is not necessary to increase the inner diameter of the cannula 14 in advance in order to insert the terminal 7 into the cored polymer cannula 14. Therefore, the cored polymer cannula 14 is reduced in size and the cost is reduced, and the polymer cannula 10 is not forcibly expanded in diameter, and the electrical performance can be further improved.

  In the cable dry-type end portion of the above embodiment, the single-layered polymer sleeve 10 is used, but a two-layered polymer sleeve 3 as shown in FIG. 5 may be used. The polymer sleeve 3 in this case includes, for example, a normal temperature shrinkable inner tube 3a formed of an elastic insulating mixture based on a polymer material such as EPR and silicone rubber as described above, and EPR and silicone rubber. It has a two-layer structure with an outer tube 3b formed of an anti-tracking insulating mixture in which an anti-tracking material or the like is blended with a polymer material as a filler. The cap portion 4 is integrally formed on the outer peripheral surface of the outer layer pipe 3b. Even if such a two-layered polymer sleeve 3 is used, the same effects as those of the above embodiment can be obtained, and the resistance to tracking is increased, which can be adapted to an environment of higher voltage conditions. . Furthermore, it goes without saying that the polymer sleeve 3 may have a multilayer structure of three or more layers as required.

It is sectional drawing which shows one Embodiment of the cable dry termination | terminus part which concerns on this invention. It is an expanded sectional view of the A section of FIG. It is a graph which expands and shows the analysis result of the electric field in the stress cone front-end | tip vicinity of the cable dry termination | terminus part of FIG. FIG. 2 is a cross-sectional view showing a state in which a cable end portion subjected to a terminal treatment is inserted into a polymer sleeve with a core and arranged at a predetermined position in order to assemble the cable dry termination portion of FIG. 1. It is sectional drawing which shows the conventional cable dry termination | terminus part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cable end part 2 Cable insulator 3 Polymer sleeve 3a Inner layer pipe 3b Outer layer pipe 4 Cap part 5 Stress cone 6 Cable conductor 6a Cable conductor extraction part 7 Terminal 7a Terminal press-contact part 9 Attachment body 10 Polymer sleeve 11 High dielectric layer 12 Equipotential Line 13 Reinforcement Core Material 14 Core Polymer Sleeve 15 Core Member 15a String

Claims (2)

  In a cable dry termination unit in which a cold-shrinkable polymer cannula having multi-stage shades on the outer peripheral surface is provided on the cable insulator at the cable end, at least from the part where the polymer cannula is provided in the cable conductor A cable dry-type terminal portion, wherein a reinforcing core material is inserted over a range up to a portion where the cable end portion is fixed.   A high-dielectric layer having a dielectric constant higher than that of the polymer cannula is integrally formed on the base side of the polymer cannula so as to be positioned at least in the inner layer portion of the cannula in the vicinity thereof. The cable dry termination unit according to claim 1.

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