JP4892053B2 - Polymer sleeve - Google Patents

Description

  The present invention relates to a polymer cannula, and more particularly to a polymer cannula provided with an electric field relaxation layer at the interface between an insulator such as an epoxy bushing and a polymer coating such as silicone rubber.

  Recently, from the viewpoint of reducing the weight of the cannula, slimming down, reducing the size of the cannula, standardizing the cannula type and simplifying the work process, a polymer covering such as silicone rubber has been applied to the surface of an insulator such as an epoxy bushing. A directly molded solid insulating structure (completely dry) polymer cannula is used (for example, Patent Document 1).

  However, in the polymer sleeve having such a configuration, when the electric field is high, a corona discharge is generated on the outer surface of the polymer sleeve, and when the corona discharge occurs over a long period of time, the polymer coating is chemically It suffers from erosion due to excessive erosion.

  In order to prevent the occurrence of such corona discharge, it is necessary to reduce the electric field strength of the air surface of the polymer cannula. As a method for reducing such electric field strength, (a) an insulator, a polymer coating, There are known a method for providing an electric field relaxation layer at the interface (for example, Patent Document 2) and a method for increasing the outer diameter of the polymer coating (for example, Patent Document 3).

  However, in the method (A), although heat generation does not occur at the operating voltage if the conventional voltage specification (66/77 kV) is used, when the operating voltage rises to, for example, about 154 kV, the electric field relaxation layer is generated at the operating voltage. There is a problem that heat is generated by switching and the problem of deterioration cannot be ignored.

  Here, it is understood that the above heat generation phenomenon is caused by the voltage-current characteristics of the electric field relaxation layer. That is, as shown in FIG. 4, the voltage-current characteristic of the electric field relaxation layer is non-linear and almost no current flows at an operating voltage of 66 to 77 kV (A part in the figure), but the operating voltage is about 154 kV (B in the figure). A portion where the electric field is concentrated, a large current flows in the electric field relaxation layer, and heat is generated by the current, that is, in the electric field relaxation layer in the vicinity of the shielding member 400 of the polymer sleeve as shown in FIG. It is understood. In FIG. 5, reference numeral 100 denotes a conductor lead bar, 200 denotes an insulator, 300 denotes a polymer coating, 310 denotes a collar portion of the polymer coating, and 500 denotes an electric field relaxation layer.

  On the other hand, in the method (b), although the electric field strength on the air surface (the portion 310 of the brim part 310 of the polymer coating 300) can be lowered to some extent, the electric field strength equivalent to that obtained by the method (b) In order to achieve this, the outer diameter of the polymer covering 300 must be increased more than necessary. For this reason, in the method (b), the outer diameter of the polymer covering 300 is further increased. The increase in the surface area of the air termination causes a decrease in salt damage characteristics, and the need for more insulating material increases the weight and cost of the cable termination connection.

JP 2003-303632 A JP 2005-117806 A JP 2002-157932 A

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a polymer cannula capable of increasing the operating voltage while suppressing an increase in the diameter of the polymer cannula.

Polymer bushing is a first aspect of the present invention includes a conductor pull bar which is centrally arranged, and an insulator of rigid are found provided on the outer periphery of the conductor pull-out, many on the outer circumference provided on the outer periphery of the insulator And a lower end portion of the conductor lead-out rod is penetrated from the lower end portion of the insulator, and is in the vicinity of the lower end portion of the insulator and at the lower end of the polymer cover body. The portion corresponding to the portion is provided with a large-diameter portion having a tapered portion that smoothly expands from the high-pressure side to the low-pressure side on the outer surface, and a zinc oxide layer is provided at the interface between the large-diameter portion and the polymer coating Alternatively, an electric field relaxation layer composed of a high dielectric constant layer is provided, and a cylindrical shielding fitting is embedded concentrically with the conductor lead bar in the large diameter portion of the insulator, and the electric field relaxation layer is electrically connected to the shielding fitting. It is in contact.

  According to a second aspect of the present invention, in the polymer cannula according to the first aspect, the tapered portion is processed so as to exhibit a smooth curved convex shape.

According to a third aspect of the present invention, in the polymer cannula according to the first aspect or the second aspect, the electric field relaxation layer is integrally formed on the outer periphery of the large diameter portion by a mold .

The polymer sleeve of the present invention has the following effects.

  First, a large diameter portion is provided in the vicinity of the shielding metal fitting where the electric field of the insulator is concentrated, that is, in the vicinity of the lower end portion of the insulator and above the conductor insertion hole of the conductor lead bar. By providing the electric field relaxation layer at the interface with the covering, the electric field strength on the air surface of the polymer cannula can be lowered, and heat generation of the electric field relaxation layer can be suppressed. Therefore, according to the cable terminal connection portion using the polymer sleeve of the present invention, it is possible to increase the operating voltage while suppressing an increase in the size of the polymer sleeve.

  Second, the concentration of the electric field can be alleviated by providing a tapered portion that gradually increases in diameter from the high pressure side toward the low pressure side on the outer surface of the large diameter portion of the insulator.

  Third, the concentration of the electric field can be further alleviated by subjecting the outer surface of the tapered portion to curved surface processing, that is, processing that exhibits a smooth curved convex shape.

  Hereinafter, preferred embodiments of the polymer cannula of the present invention will be described with reference to the drawings. In the following description, the “leading end portion” of the conductor lead bar, the insulator (including the large-diameter insulator, the small-diameter insulator, and the large-diameter portion), the shielding fitting (including the cylindrical portion and the funnel-shaped portion), and the electric field relaxation layer. ”Refers to the high voltage side, which corresponds to the upper direction in the figure, and the“ lower end ”of the conductor lead bar, insulator, shielding metal fitting, and electric field relaxation layer refers to the low voltage side, and is the lower side in the figure. Corresponds to the direction.

  FIG. 1 shows a partial cross-sectional view of an air terminal connection portion of a 154 kV class CV cable using the polymer sleeve of the present invention.

  In the figure, a polymer cannula 1 of the present invention includes a conductor lead bar 2 disposed at the center and having a conductor insertion hole 2a at the lower end, and a hard insulator 3 provided on the outer periphery of the conductor lead bar 2. And a polymer covering 4 provided on the outer periphery of the insulator 3. Here, the conductor lead-out rod 2 is formed of a metal rod suitable for energization such as copper, and the insulator 3 is formed of a material having high mechanical strength, for example, a hard plastic resin such as epoxy resin or FRP. . The polymer covering 4 is formed of a material having excellent electrical insulation performance, for example, a polymer insulating material such as silicone polymer. The insulator 3, the polymer cover 4, and the electric field relaxation layer 5 described later are integrally formed by a mold.

  The insulator 3 includes a large-diameter insulator 31 provided on the outer periphery of the conductor insertion hole 2a of the conductor lead-out rod 2 across a lower end portion of a shielding metal fitting 6 to be described later from the lower portion of the conductor insertion hole 2a, and the conductor lead-out rod 2 A small-diameter insulator 32 provided on the outer periphery of the shield member 6 from the vicinity of the tip thereof to the vicinity of the upper end of the shielding metal fitting 6 to be described later, and a large-diameter portion provided in a connecting portion of the large-diameter insulator 31 and the small-diameter insulator 32. 33, and a receiving port 31a having a funnel-shaped tapered inner peripheral surface for receiving a stress cone 71 of the cable terminal portion 7 described later communicates with the conductor insertion hole 2a at the lower end portion of the large-diameter insulator 31. And concentrically with the conductor insertion hole 2a. Further, the outer surface of the large-diameter portion 33 is provided with a tapered portion 33a that smoothly increases in diameter from the tip end side (high pressure side) to the lower end portion side (low pressure side). In this embodiment, the outer surface of the tapered portion 33a has a curved curved convex shape by applying curved surface processing to a portion from the upper end portion side to the lower end portion side of the large diameter portion 33. The outer diameter of the large-diameter insulator 31 is 1.5 to 1.7 times the outer diameter of the small-diameter insulator 32, and the outer diameter on the lower end side of the large-diameter portion 33 is that of the large-diameter insulator 31. The outer diameter on the upper end side of the large diameter portion 33 is substantially the same as the outer diameter of the small diameter insulator 32. The axial lengths of the large-diameter insulator 31 and the large-diameter portion 33 are about 1/5 of the axial length of the insulator 3, and the axial length of the small-diameter insulator 32 is the insulator. The axial length of 3 is about 3/5.

  Reference numeral 6 denotes a cylindrical shielding metal fitting that surrounds the conductor extraction rod 2 in the large diameter portion 33 of the insulator 3 and is concentrically embedded with the conductor extraction rod 2. A cylindrical part 61 is embedded in the continuous part of the body 31 and the large diameter part 33 so as to expose only its outer surface, and is connected to the upper end of the cylindrical part 61 concentrically with the cylindrical part 61. A tapered funnel 62 embedded in the large diameter portion 33 concentrically with the large diameter portion 33 with its upper end facing the small diameter insulator 32 side, and a cylindrical portion 61 at the lower end of the cylindrical portion 61. And an annular flange portion 63 which is provided concentrically and extends outward in the radial direction from the position of the upper end portion of the large-diameter insulator 31. Here, the inner diameter of the cylindrical portion 61 is substantially the same as the outer diameter of the large-diameter insulator 31.

The polymer cover 4 is provided on the outer periphery from the lower end portion of the large diameter portion 33 to the tip end portion of the small diameter insulator 32, and a plurality of flanges 4 a are provided in the longitudinal direction of the polymer cover 4 on the outer periphery thereof. It is formed so as to be spaced apart along. In addition, an electric field relaxation layer 5 is provided at the interface between the large diameter portion 33 and the polymer coating 4, and the lower end portion side of the electric field relaxation layer 5 is in electrical contact with the upper end portion of the cylindrical portion 61 constituting the shielding metal fitting 6. is doing.
Here, the electric field relaxation layer 5 is formed of a high dielectric constant layer having a relative dielectric constant of 10 or more, such as a ZnO layer filled with zinc oxide powder in an elastomer material or a rubber filled with a conductive filler such as carbon black. Yes.

  Next, a cable terminal connection portion using the polymer sleeve 1 of the present invention will be described.

  In FIG. 1, first, a tulip contact type conductor connector 2c extending and contracting in the radial direction is mounted on a cylindrical boss 2b projecting from a back wall of a conductor insertion hole 2a of a conductor lead bar 2. ing. In addition, an annular bottom metal fitting 8 is fixed to the lower end surface of the outer peripheral edge of the flange 63 constituting the shielding metal fitting 6 via a fastening bolt B, and the bottom metal fitting 8 is disposed on the lower surface side thereof. The support frame 10 is attached via the support insulator 9. Thereby, the polymer sleeve 1 is fixed to the support frame 10 via the support insulator 9. Further, a stress cone 71 is mounted on the outer periphery of the cable insulator 72 exposed by stripping the cable terminal, and a bullet shape that can be plug-in connected to the conductor connector 2c at the tip of the cable conductor 73. The conductor terminal 74 is attached. Here, the stress cone 71 is made of a pre-mold insulator having rubber-like elasticity such as ethylene propylene rubber (EP rubber), and the tip of the stress cone 71 is tapered to be attached to the inner wall surface of the receiving port 31a. A cone-shaped part is provided.

  The end portion of the cable terminal portion 7 having such a configuration is inserted toward the receiving port 31a of the polymer cannula 1, and then the pressing metal 75 previously disposed on the cable terminal portion 7 side is directed toward the receiving port 31a side. Pressed. As a result, the conductor terminal 74 is plug-in connected to the conductor connector 2c, and the cone-shaped portion of the stress cone 71 is pressed against the inner wall surface of the receiving port 31a. As a result, the inner wall surface of the receiving port 31a and the cone-shaped portion The insulation performance of the interface between the outer peripheral surfaces is ensured.

  In FIG. 1, reference numeral 76 denotes a cable shielding layer, 77 denotes a seal portion, 78 denotes a pressing flange, 79 denotes a ground wire, 80 denotes a spring, 81 denotes a protective fitting, and 82 denotes an adapter.

  FIG. 2 shows an electric field analysis diagram in the cable termination connection portion of the present invention. As is clear from the figure, the cable termination connection portion of the present invention has a uniform electric field on the outer surface of the polymer sleeve 1 in the vicinity of the shielding metal fitting 6 as is apparent in comparison with the conventional cable termination connection portion (see FIG. 5). It can be seen that the concentration of the electric field is relaxed.

  As described above, the outer diameter of the insulator 3 in the vicinity of the shielding metal fitting 6 where the electric field concentrates is increased, and the electric field relaxation layer is formed at the interface between the increased diameter insulator (large diameter portion 33) and the polymer coating 4. According to the cable terminal connection portion of the present invention provided with 5, the electric field strength on the air surface of the polymer cannula 1 can be lowered, and the heat generation of the electric field relaxation layer 5 can be suppressed, that is, as shown in FIG. Furthermore, the electric field relaxation is achieved because the switching voltage (C portion in the figure) in the cable termination connection portion (example) of the present invention is higher than the switching voltage (B portion in the drawing) in the conventional cable termination connection portion (comparative example). Heat generation of the layer 5 can be suppressed. Furthermore, by providing the outer surface of the large-diameter portion 33 of the insulator 3 with a tapered portion 33a that gradually increases in diameter from the high-pressure side to the low-pressure side, the concentration of the electric field can be alleviated, and further if necessary. Thus, by applying curved surface processing (processing that exhibits a smooth curved convex shape) to the outer surface of the tapered portion 33a, the concentration of the electric field can be further reduced.

  In the above-described embodiments, the present invention is described with specific embodiments shown in the drawings. However, the present invention is not limited to these embodiments, and as long as the effects of the present invention are exhibited, It may be as follows.

  1stly, in the above-mentioned Example, although the electric field relaxation layer 5 is provided in the interface of the large diameter part 33 and the polymer coating body 4, the said electric field relaxation layer 5 is provided ranging over the outer periphery of a small diameter insulator. Or may be provided over the entire length of the interface.

  Secondly, the insulator 3 provided on the outer periphery of the conductor lead bar 2 may be provided separately from the conductor lead bar 2.

  Thirdly, in the above-described embodiment, the air terminal connection portion has been described. However, the present invention is not limited to this, and may be applied to an air portion such as a through bushing.

  Fourthly, the conductor lead-out rod 2 is not limited to one formed of copper, and may be formed of any one of copper alloy, aluminum, or aluminum alloy, for example.

  Fifth, in the above-described embodiment, the operation voltage is 154 kV class, but the present invention is not limited to this, and may be applied to a voltage lower than 154 kV or higher. .

The partial sectional view of the cable termination connection part of the present invention. The electric field analysis figure in the cable termination connection part of this invention. The voltage-current characteristic figure in the cable termination connection part of this invention. The voltage-current characteristic figure in the conventional cable termination connection part. The electric field analysis figure in the conventional cable termination connection part.

DESCRIPTION OF SYMBOLS 1 ... Polymer sleeve 2 ... Conductor extraction rod 2a ... Conductor insertion hole 3 ... Insulator 33 ... Large diameter part 33a ... Tapered part 4 ... Polymer coating | cover 4a ...襞 part 5 ... electric field relaxation layer 6 ... shielding metal fitting 7 ... cable end

Claims (3)

A conductor lead bar disposed in the center;
An insulator of rigid provided et the outer periphery of the conductor pull bar,
A polymer coating provided on the outer periphery of the insulator and formed with a number of flanges spaced apart in the longitudinal direction on the outer periphery;
The lower end portion of the conductor lead bar is penetrated from the lower end portion of the insulator ,
In the vicinity of the lower end portion of the insulator and corresponding to the lower end portion of the polymer coating, a large diameter portion having a tapered portion that smoothly expands from the high pressure side toward the low pressure side is provided on the outer surface. ,
An electric field relaxation layer composed of a zinc oxide layer or a high dielectric constant layer is provided at the interface between the large diameter portion and the polymer covering,
In the large diameter portion of the insulator, a cylindrical shielding metal fitting is concentrically embedded with the conductor lead bar,
The polymer sleeve, wherein the electric field relaxation layer is in electrical contact with the shielding fitting.   The polymer sleeve according to claim 1, wherein the taper portion is processed so as to exhibit a smooth curved convex shape.   3. The polymer sleeve according to claim 1, wherein the electric field relaxation layer is integrally formed on the outer periphery of the large diameter portion by a mold.

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