JP6916396B2 - Power cable termination connection and power cable termination connection method - Google Patents

Description

The present invention relates to a power cable termination connection portion and a power cable termination connection method capable of suppressing the occurrence of dielectric breakdown on the vertically upper side of the electric field relaxation rubber unit.

Conventionally, the terminal connection portion for a power cable is generally covered with an insulating porcelain tube filled with insulating oil around the rubber unit for electric field relaxation attached to the power cable (see Patent Documents 1 and 2). ..

Japanese Unexamined Patent Publication No. 2006-60981 Japanese Unexamined Patent Publication No. 2004-80923

By the way, the conventional rubber unit for electric field relaxation has a cylindrical shape, and the vertical upper side, which is crimped to the power cable, is flat. When the vertical upper side is flat, a pressing surface for inserting the electric field relaxation rubber unit from the vertical upper side is formed, so that the electric field relaxation rubber unit can be easily mounted. This is because the electric field relaxation rubber unit can be pushed into the power cable by applying a plate-shaped insertion jig to the flat portion. The electric field relaxation rubber unit is crimped to the power cable by the contraction force of the rubber, and a stable interface pressure is maintained for a long period of time.

However, when the terminal connection portion for the power cable is erected in the vertical direction, foreign matter falling from the vertical upper side tends to accumulate on the flat portion on the vertical upper side. Here, the points where the rubber unit for electric field relaxation, the insulating oil, and the power cable come into contact with each other are likely to be the starting points of dielectric breakdown. The flat part of the electric field relaxation rubber unit and the contact point with the power cable is the place where the electric field relaxation rubber unit, the insulating oil, and the power cable come into contact with each other. It can occur.

It should be noted that a configuration in which the rubber unit for electric field relaxation is inclined toward the vertical upper portion on the vertical upper side side to prevent foreign matter from accumulating can be considered, but in such a configuration, the interface surface of the rubber unit for electric field relaxation to the power cable. The pressure may decrease and the insulation performance may decrease. Further, in such a configuration, since the power cable repeatedly expands and contracts due to the temperature change, the electric field relaxation rubber unit may be torn from the small diameter portion side of the inclined portion.

The present invention has been made in view of the above, and provides a power cable termination connection portion and a power cable termination connection method capable of suppressing the occurrence of dielectric breakdown on the vertically upper side of the electric field relaxation rubber unit. The purpose is to do.

In order to solve the above-mentioned problems and achieve the object, the power cable termination connection according to one aspect of the present invention covers the power cable erected vertically upward and the periphery of the power cable. A tubular first rubber unit provided by crimping to the power cable between the insulating porcelain tube and a vertically upper side of the first rubber unit formed around the power cable. A second rubber unit made of an insulating material having a radius of the outermost peripheral edge larger than the radius of the outermost peripheral edge of the first rubber unit is provided.

Further, in the power cable termination connection portion according to one aspect of the present invention, all or a part of the power cable side is inclined toward the outer peripheral edge side vertically above the outermost peripheral edge of the second rubber unit. However, the second rubber unit is characterized in that it is not in contact with the inner wall of the insulating porcelain tube over the entire circumference.

Further, the power cable terminal connection portion according to one aspect of the present invention is characterized in that the vertically lower side from the outermost peripheral edge of the second rubber unit is inclined toward the power cable side. ..

Further, the power cable terminal connection portion according to one aspect of the present invention is characterized in that the first rubber unit and the second rubber unit are not in contact with each other.

Further, in the power cable termination connection portion according to one aspect of the present invention, the inner diameter of the second rubber unit into which the power cable is inserted is larger than the inner diameter of the first rubber unit into which the power cable is inserted. Is also large, and is characterized in that it is smaller than the outer diameter of the power cable.

Further, the terminal connection portion for a power cable according to one aspect of the present invention is characterized in that the vertically upper side of the first rubber unit has a flat portion.

Further, the power cable termination connection portion according to one aspect of the present invention is located between the insulating porcelain tube and the power cable in a region where the first rubber unit and the second rubber unit are arranged. Is characterized in that it is filled with at least insulating oil.

Further, the terminal connection portion for a power cable according to one aspect of the present invention is located between the insulating porcelain tube and the power cable in a region where the first rubber unit and the second rubber unit are arranged. Is characterized in that it is filled with at least an insulating gas.

Further, the power cable termination connection method according to one aspect of the present invention is between the power cable erected vertically upward and the insulating porcelain tube that covers the periphery of the power cable, and the power cable is connected to the power cable. A tubular first rubber unit provided by crimping, and a vertically upper side of the first rubber unit, formed around the power cable, and having a radius of the outermost peripheral edge of the first rubber unit. A second rubber unit made of an insulating material larger than the radius of the outermost peripheral edge of the second rubber unit is provided, and the outer periphery is all or a part of the power cable side vertically above the outermost peripheral edge of the second rubber unit. It is characterized in that it is inclined toward the edge side and the second rubber unit is not in contact with the inner wall of the insulating porcelain tube.

According to the present invention, it is possible to suppress the occurrence of dielectric breakdown on the vertically upper side of the first rubber unit, which is a rubber unit for electric field relaxation.

FIG. 1 is a front view showing a schematic configuration of a terminal connection portion for a power cable according to an embodiment of the present invention, including a partial breakage. FIG. 2 is a diagram showing a detailed configuration of the electric field relaxation rubber unit. FIG. 3 is an explanatory diagram showing the relationship between the inner diameter of the rubber unit for electric field relaxation and the rubber unit for barrier and the outer diameter of the power cable. FIG. 4 is a cross-sectional view taken along the line AA of the terminal connection portion for the power cable shown in FIG. FIG. 5 is a diagram showing a configuration of a rubber unit for a barrier according to a modification 1 of the embodiment of the present invention. FIG. 6 is a diagram showing a configuration of a rubber unit for a barrier according to a modification 2 of the embodiment of the present invention. FIG. 7 is a diagram showing a configuration of a barrier rubber unit according to a modification of the embodiment of the present invention. FIG. 8 is a diagram showing a configuration of a terminal connection portion for a power cable, which is a modification 4 of the embodiment of the present invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

<Overview of terminal connection for power cable>
FIG. 1 is a front view showing a schematic configuration of a power cable terminal connection portion 1 according to an embodiment of the present invention, including a partial breakage. As shown in FIG. 1, the power cable terminal connection portion 1 has a power cable 11 erected vertically upward (Z direction) and an insulating porcelain tube 10 that covers the periphery of the power cable. In the region E1 between the electric power cable 11 and the insulating porcelain tube 10, an electric field relaxation rubber unit 12 which is a first tubular rubber unit provided by crimping to the electric power cable 11 and an electric field relaxation rubber unit It has a second rubber unit formed on the vertically upper side of the 12 and around the power cable 11, and is made of an insulating material whose outermost peripheral edge radius is larger than the outermost peripheral edge radius of the electric field relaxation rubber unit 12. .. The second rubber unit is, for example, a barrier rubber unit 15, but is not limited to this. The barrier rubber unit 15 has a function of preventing foreign matter falling from the head side from accumulating on the lower electric field relaxation rubber unit 12. Further, the region E1 is filled with insulating oil 16. Instead of the insulating oil 16, an insulating gas may be filled as an insulating medium. The electric power cable 11 may be an AC power transmission power cable or a DC power transmission power cable. The power cable 11 shown in FIG. 1 is a power cable for AC power transmission having a nominal 66 kV class or higher. Further, the insulating porcelain tube 10 has folds at regular intervals. Further, the insulating porcelain tube 10 may be any material having an insulating property, and is, for example, a plastic including ceramic, rubber, or fiber reinforced plastic. The material of the barrier rubber unit 15 may be an insulating material, for example, a synthetic elastomer. Examples of the synthetic elastomer include ethylene propylene rubber and silicon rubber. The barrier rubber unit 15 may be made of a material having conductivity in which a conductive material such as conductive rubber or semi-conductive rubber is dispersed, as long as there is no problem in insulation performance.

A shield ring 17 is provided on the head of the insulating porcelain tube 10. Although the detailed configuration is omitted, the shield ring 17 has a hollow inside and is connected to the region E1. When a temperature change occurs, the insulating oil and air expand or contract, and as shown by arrow A2, the insulating oil and air enter and exit between the shield ring 17 and the region E1 in the insulating porcelain tube 10, and the shield ring. Reference numeral 17 has a reservoir function of insulating oil or air.

<Structure of rubber unit for electric field relaxation>
FIG. 2 is a diagram showing a detailed configuration of the electric field relaxation rubber unit 12. As shown in FIG. 2, the electric field relaxation rubber unit 12 has an insulator portion 13 and a semiconductor portion 14 integrally molded with the insulator portion 13. The electric field relaxation rubber unit 12 is arranged so that the semiconductor portion 14 is located on the external semi-conductive layer 11a exposed by the step stripping treatment and the insulator portion 13 is located on the cable insulator 12a exposed by the step stripping treatment. .. The material of the cable insulator 12a is, for example, a plastic such as cross-linked polyethylene. The semiconductor portion 14 and the external semi-conductive layer 11a are those in which the conductive material is dispersed in the insulating material, and may be, for example, a resin containing conductive carbon. The material of the insulator portion 13 is, for example, a synthetic elastomer. Examples of the synthetic elastomer include ethylene propylene rubber and silicon rubber. The thickness of the electric field relaxation rubber unit 12 is preferably a thickness at which a desired interface pressure can be obtained.

As shown in FIG. 2, the electric field relaxation rubber unit 12 has a tapered shape in which the semiconductor portion 14 expands vertically upward to coarsen the density of the equipotential lines L1 and alleviate the concentration of the electric field. Dielectric breakdown can be suppressed.

<Rubber unit for barrier>
As shown in FIG. 1, an inclined surface S1 inclined toward the outer peripheral edge side of the power cable 11 side is formed on the vertically upper side (+ Z direction) from the outermost peripheral edge of the barrier rubber unit 15. Moreover, as described above, the radius of the outermost peripheral edge of the barrier rubber unit 15 is larger than the radius of the outermost peripheral edge of the electric field relaxation rubber unit 12. As a result, as shown by the arrow A1 in FIG. 1, the foreign matter falling from the head side does not deposit on the inclined surface S1 and also does not deposit on the flat surface S3 of the electric field relaxation rubber unit 12, and the insulated porcelain tube. It falls to the bottom of 10. Since the electric field stress is weak at the bottom, there is no problem even if foreign matter accumulates.

As a result, foreign matter does not accumulate on the flat surface S3 of the electric field relaxation rubber unit 12, and the starting point is a point (triple junction portion) where the electric field relaxation rubber unit 12, the insulating oil 16, and the power cable 11 come into contact with each other. Dielectric breakdown is suppressed.

The foreign matter is, for example, metal powder or the like when the head is bolted at the time of assembling the terminal connection portion 1 for the power cable. In addition, foreign matter may be mixed and dropped when air or insulating oil enters or exits between the shield ring 17 and the region E1 in the insulating porcelain tube 10 after assembly.

Moreover, a flat surface S3 is formed on the vertically upper portion of the electric field relaxation rubber unit 12, and by using this flat surface S3 as a pressing surface when mounting the electric field relaxation rubber unit 12, the electric field relaxation is performed. The rubber unit 12 can be easily attached. This is because the electric field relaxation rubber unit 12 can be pushed into the power cable 11 by applying a plate-shaped insertion jig to the flat surface S3.

The electric field relaxation rubber unit 12 and the barrier rubber unit 15 are separated from each other in a non-contact manner. The distance between the electric field relaxation rubber unit 12 and the barrier rubber unit 15 should be as close as possible, but it is preferable that the distance is one or less of the barrier rubber unit 15 for removing foreign matter.

Further, an inclined surface S2 inclined toward the power cable 11 side is formed on the vertically lower side (−Z direction) from the outermost peripheral edge of the barrier rubber unit 15. As a result, it is possible to prevent air bubbles generated when the insulating oil is injected or due to a temperature change from accumulating in the lower portion of the barrier rubber unit 15 and to prevent dielectric breakdown.

Further, the barrier rubber unit 15 is in non-contact with the inner wall of the insulating porcelain tube 10 over the entire circumference. As a result, the heat dissipation in the front band inside the insulating porcelain tube 10 is improved without hindering the convection of the medium such as the insulator or gas inside the insulating porcelain tube 10 above and below the outer edge portion of the barrier rubber unit 15. be able to.

The barrier rubber unit 15 may be additionally installed on the power cable termination connection 1 having the electric field relaxation rubber unit 12 without being affected by other structures, and is a conventional power cable termination connection. There is no design change for 1.

Further, the lowermost portion of the power cable terminal connection portion 1 has a base 31, and an insulator 33 that stands on the base 31 and supports the upper insulating porcelain tube 10 and the power cable 11. The number of insulators 33 is preferably four or more, and the insulators 33 are arranged substantially evenly. The insulator 33 may be connected via the leg portion 32.

<Inner diameter of rubber unit for electric field relaxation and rubber unit for barrier>
FIG. 3 is an explanatory diagram showing the relationship between the inner diameters d2 and d3 of the electric field relaxation rubber unit 12 and the barrier rubber unit 15 and the outer diameter d1 of the power cable 11. The outer diameter d1 indicates the diameter of the insulator portion of the power cable 11. As shown in FIG. 3, the inner diameter d3 of the barrier rubber unit 15 into which the power cable 11 is inserted is larger than the inner diameter d2 of the electric field relaxation rubber unit 12 into which the power cable 11 is inserted, and is outside the power cable 11. It is smaller than the diameter d1.

The inner diameter d3 of the barrier rubber unit 15 may be the same as the inner diameter d2 of the electric field relaxation rubber unit 12, but it is better to be larger than the inner diameter d2 of the electric field relaxation rubber unit 12. When the inner diameter d3 of the barrier rubber unit 15 is made larger than the inner diameter d2 of the electric field relaxation rubber unit 12, the tightness of the rubber is weakened and the interface pressure with the power cable 11 is reduced. The strength of the interface pressure of the barrier rubber unit 15, that is, the strength of the insulating property is not required. On the contrary, when the inner diameter d3 of the barrier rubber unit 15 is made larger than the inner diameter d2 of the electric field relaxation rubber unit 12, the tightness of the rubber is weakened, so that the barrier rubber unit 15 can be easily attached to the power cable 11. It can be externally inserted, and tearing due to expansion and contraction of the power cable 11 is less likely to occur. An inclined surface S1 is formed on the vertically upper portion of the barrier rubber unit 15, but even if the pressing surface is the inclined surface S1, the rubber is weakly tightened, so that it can be easily extrapolated to the power cable 11.

Specifically, the inner diameter d2 is smaller than the outer diameter d1 by about 20 to 30 mm, and the inner diameter d3 is smaller than the outer diameter d1 by about 2 to 10 mm. The barrier rubber unit 15 is in non-contact with the inner wall of the insulating porcelain tube 10 over the entire circumference. Further, the electric field relaxation rubber unit 12, the barrier rubber unit 15, the electric power cable 11, and the insulating porcelain tube 10 are located on concentric circles centered on the central axis of the electric power cable 11, respectively. For example, the electric field relaxation rubber unit 12, the barrier rubber unit 15, the electric power cable 11, and the insulating porcelain tube 10 are formed in a rotating body shape centered on the central axis 11c of the electric power cable 11, as shown in FIG. NS.

In the voltage class of 380 kV or higher, the possibility of dielectric breakdown cannot be ignored due to the accumulation of foreign matter in the rubber unit 12 for electric field relaxation, so it is desirable to use the configuration of the above embodiment. Further, at a voltage of 500 kV class or higher, the possibility of dielectric breakdown further increases, so that the configuration of the above embodiment is more preferable.

Further, when the length L10 of the insulating porcelain tube 10 shown in FIG. 1 is 2.5 m or more, it is used in a voltage environment substantially equal to or higher than the voltage class 380 kV, and therefore, it is desirable to use the above embodiment. The length L10 is the distance between the metal portion 41 of the upper portion of the insulating porcelain tube 10 and the metal portion 42 of the lower porcelain tube.

<Modification example 1>
FIG. 5 is a diagram showing the configuration of the barrier rubber unit 21 according to the first modification of the embodiment of the present invention. As shown in FIG. 5, in the barrier rubber unit 21 corresponding to the barrier rubber unit 15, the vertical upper portion of the barrier rubber unit 15 is not all the inclined surface S1, but one on the power cable 11 side. The portion is an inclined surface S1a, and a part on the outer peripheral edge side is a flat surface S1b. Even if foreign matter is deposited on the flat surface S1b, the occurrence of dielectric breakdown can be suppressed.

<Modification 2>
FIG. 6 is a diagram showing a configuration of a barrier rubber unit 22 according to a modification 2 of the embodiment of the present invention. As shown in FIG. 6, the barrier rubber unit 22 corresponding to the barrier rubber unit 15 has an arc shape instead of an inclined plane like the inclined surfaces S1 and S2. Even with this arc shape, the same effect as that of the barrier rubber unit 15 can be obtained.

<Modification example 3>
FIG. 7 is a diagram showing a configuration of a barrier rubber unit 23 according to a modification of the embodiment of the present invention. As shown in FIG. 7, the barrier rubber unit 23 corresponding to the barrier rubber unit 15 does not have the same inclination angle as the inclined surfaces S1 and S2, but has an inclined surface S11 corresponding to the inclined surface S1 and an inclined surface. The inclination angle with the inclined surface S21 corresponding to S2 is different. In FIG. 7, the angle of the inclined surface S21 is smaller than the angle of the inclined surface S11 in the vertical direction.

<Modification example 4>
FIG. 8 is a diagram showing a configuration of a terminal connection portion for a power cable, which is a modification 4 of the embodiment of the present invention. The power cable termination connection of the modified example 4 shown in FIG. 8 has an epoxy seat 114, and is a prefab that suppresses dielectric breakdown in combination with an electric field relaxation rubber unit 113 that is crimped around the power cable 110. It is a type of terminal connection, and the interface pressure is obtained by the spring 115. Insulating oil 116 is also filled in the terminal connection portion for the power cable of the modified example 4.

Also in this modification 4, the barrier rubber unit 15 is provided vertically above the electric field relaxation rubber unit 113 to prevent foreign matter from accumulating on the electric field relaxation rubber unit 113. In this case as well, only the barrier rubber unit 15 is added, and there is no significant design change.

Although the embodiments and modifications to which the invention made by the present inventors has been applied have been described above, the present invention may be limited by the descriptions and drawings that form a part of the disclosure of the present invention according to the present embodiments. do not have. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

1 Termination connection for power cable 10 Insulator tube 11,110 Power cable 11a External semi-conductive layer 11c Central axis 12,113 Electric field relaxation rubber unit 12a Cable insulator 13 Insulator part 14 Semiconductor part 15,21,22,23 Rubber unit for barrier 16,116 Insulating oil 17 Shield ring 31 Base 32 Leg 33 Insulator 41, 42 Insulator Metal part 114 Epoxy seat 115 Spring A1, A2 Arrow d1 Outer diameter d2, d3 Inner diameter E1 Region L1 Equal potential line L10 Length S1, S2, S11, S1a, S21 Inclined surface S1b, S3 Flat surface

Claims (7)

A tubular first rubber unit provided by crimping to the electric power cable between the electric power cable erected vertically upward and an insulating porcelain tube covering the periphery of the electric power cable.
A second insulating material formed on the vertically upper side of the first rubber unit and around the power cable and having a radius of the outermost peripheral edge larger than the radius of the outermost peripheral edge of the first rubber unit. Rubber unit and
With
A power cable termination connection portion characterized in that the vertically lower side from the outermost peripheral edge of the second rubber unit is inclined toward the power cable side. On the vertically upper side of the second rubber unit from the outermost peripheral edge, all or a part of the power cable side is inclined toward the outer peripheral edge side.
The terminal connection portion for a power cable according to claim 1, wherein the second rubber unit is not in contact with the inner wall of the insulating porcelain tube over the entire circumference. A tubular first rubber unit provided by crimping to the electric power cable between the electric power cable erected vertically upward and an insulating porcelain tube covering the periphery of the electric power cable.
A second insulating material formed on the vertically upper side of the first rubber unit and around the power cable and having a radius of the outermost peripheral edge larger than the radius of the outermost peripheral edge of the first rubber unit. Rubber unit and
With
The inner diameter of the second rubber unit into which the power cable is inserted is larger than the inner diameter of the first rubber unit into which the power cable is inserted and smaller than the outer diameter of the power cable. Termination connection for power cables. On the vertically upper side of the second rubber unit from the outermost peripheral edge, all or a part of the power cable side is inclined toward the outer peripheral edge side.
The terminal connection portion for a power cable according to claim 3, wherein the second rubber unit is not in contact with the inner wall of the insulating porcelain tube over the entire circumference. What is the inclination angle of the inclined surface on the vertically upper side from the outermost peripheral edge of the second rubber unit with respect to the vertical direction and the inclination angle of the inclined surface on the vertically lower side from the outermost peripheral edge of the second rubber unit with respect to the vertical direction? The power cable termination connection according to claim 2, wherein the power cable is different. The inclination angle of the inclined surface on the vertically lower side from the outermost peripheral edge of the second rubber unit with respect to the vertical direction is smaller than the inclination angle of the inclined surface on the vertically upper side from the outermost peripheral edge of the second rubber unit with respect to the vertical direction. The power cable termination connection according to claim 5. A tubular first rubber unit provided by crimping to the electric power cable between the electric power cable erected vertically upward and an insulating porcelain tube covering the periphery of the electric power cable.
A second insulating material formed on the vertically upper side of the first rubber unit and around the power cable and having a radius of the outermost peripheral edge larger than the radius of the outermost peripheral edge of the first rubber unit. Rubber unit and
With
On the vertically upper side of the second rubber unit from the outermost peripheral edge, all or a part of the power cable side is inclined toward the outer peripheral edge side.
The second rubber unit is in non-contact with the inner wall of the insulating porcelain tube over the entire circumference.
A terminal connection portion for a power cable, characterized in that a flat surface is formed on a part of the outermost peripheral edge side of the second rubber unit.

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