JP7495386B2 - Polymer sleeve - Google Patents

Description

The present invention relates to a polymer sleeve.

In recent years, from the perspective of making sleeves lighter, slimmer, and smaller, standardizing sleeve types, and simplifying the work process, polymer sleeves with a solid insulation structure (completely dry type) have been put to practical use, in which a polymer coating made of silicone rubber or the like is directly molded onto the outer surface of an insulating tube made of epoxy resin or the like (for example, Patent Documents 1 to 4). Such polymer sleeves are called direct mold type.

In a direct mold type polymer sleeve, the polymer jacket usually has a body that covers the outer periphery of the insulating tube, and umbrella-shaped pleats formed on the outer periphery of the body at intervals in the longitudinal direction. In addition, to improve the corona resistance characteristics, an electric field relaxation layer made of a zinc oxide layer or a high dielectric constant layer is disposed at the interface between the insulating tube and the polymer jacket (see Patent Documents 1, 3, and 4). In particular, in the polymer sleeve disclosed in Patent Document 4, the body of the polymer jacket is made thick at the outer periphery corresponding to the tip of the electric field relaxation layer, thereby further improving the corona resistance characteristics.

JP 2012-75266 A JP 2007-188735 A JP 2009-5514 A JP 2016-140195 A

For porcelain sleeves, the surface leakage distance required to reliably insulate the electricity flowing on the surface is stipulated by standards. The higher the voltage class, the longer the surface leakage distance required. In recent years, standards have also stipulated contamination design reference curves for polymer sleeves, including direct mold types, and new surface leakage distances have been established (for example, JEC-5202). Furthermore, for polymer sleeves, including direct mold types, the higher the voltage class, the higher the insulation performance required. The insulation performance required here includes, for example, contamination AC withstand voltage characteristics, and dry and water-filled power frequency flashover characteristics.

The object of the present invention is to provide a polymer sleeve that can ensure the required surface leakage distance and further improve insulation performance.

The polymer sleeve according to the present invention comprises:
A rod-shaped inner conductor disposed at the center;
a hard insulating tube integrally formed on the outer periphery of the inner conductor;
a shielding metal fitting embedded in the insulating tube concentrically with the inner conductor;
a polymer covering having a body portion covering an outer periphery of the insulating tube and a plurality of umbrella-shaped pleats formed at intervals in a longitudinal direction on the outer periphery of the body portion;
an electric field relaxation layer, which is made of a zinc oxide layer or a high dielectric constant layer, is disposed along the interface between the insulating tube and the polymer coating, and has a rear end connected to the shielding metal fitting;
The plurality of pleats include a plurality of small pleats, a plurality of large pleats arranged alternately with the plurality of small pleats in the longitudinal direction and having a greater protruding length from the body than the small pleats, and extra-large pleats arranged between adjacent small pleats in place of some of the plurality of large pleats and having a greater protruding length from the body than the large pleats,
The extra-large pleat portion includes a first extra-large pleat portion disposed at any one of the first to third sheets toward the tip side based on a position corresponding to the tip of the electric field relaxation layer in the polymer cover,
The first oversized fold is located distal to the datum.

The polymer sleeve of the present invention can ensure the required surface leakage distance and further improve insulation performance.

FIG. 1 is a partial cross-sectional view showing the overall structure of a polymer sleeve according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of an arrangement of the extra-large pleats. FIG. 3 is a partial cross-sectional view showing the overall configuration of a polymer sleeve according to a modified example.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
Fig. 1 is a partial cross-sectional view showing the overall configuration of a polymer sleeve 1 according to an embodiment of the present invention. In the following, the upper side in the drawing is referred to as the "front end side S1" and the lower side is referred to as the "rear end side S2". The polymer sleeve 1 shown in Fig. 1 is an equipment bushing having a head part H on the rear end side S2 to be disposed in an electric power equipment such as a transformer.

As shown in FIG. 1, the polymer sleeve 1 includes a rod-shaped internal conductor 10 located at the center, an insulating tube 20 provided on the outer periphery of the internal conductor 10, a shielding metal fitting 30 formed integrally with the insulating tube 20, a polymer coating 40 provided on the outer periphery of the insulating tube 20, and an electric field relaxation layer 50 located at the interface between the insulating tube 20 and the polymer coating 40.

The internal conductor 10, the insulating tube 20, the shielding metal fitting 30, the polymer coating 40, and the electric field relaxation layer 50 are integrally formed by molding. Specifically, the insulating tube 20 is molded with the internal conductor 10 and the shielding metal fitting 30 set in a mold. The molded insulating tube 20 is then set in a mold for forming the electric field relaxation layer, and the electric field relaxation layer 50 is molded on the outer circumferential surface of the large diameter portion 23 of the insulating tube 20, as described below. Furthermore, the molded electric field relaxation layer 50 is set in a mold for forming the polymer coating, and the polymer coating 40 is molded on the outer circumferential surfaces of the insulating tube 20 and the electric field relaxation layer 50. In addition, in the polymer sleeve 1, the electric potential during application of electricity is the high potential of the internal conductor 10 and the ground potential of the shielding metal fitting 30.

The inner conductor 10 is made of a conductive material suitable for electrical current flow, such as copper, aluminum, a copper alloy, or an aluminum alloy. In the polymer sleeve 1, both ends of the inner conductor 10 (the leading end 11 and the trailing end 12) are exposed from the insulating tube 20. The leading end 11 of the inner conductor 10 is connected to an overhead line or a lead wire (not shown), and the trailing end 12 of the inner conductor 10 is connected to a high-voltage conductor in the power equipment.

The insulating tube 20 is made of a hard plastic resin material with high mechanical strength, such as epoxy resin or FRP (Fiber Reinforced Plastics). The insulating tube 20 has a small diameter section 21 formed in a straight barrel shape at the tip side S1, a tapered section 22 that gradually expands in diameter from the small diameter section 21 toward the rear end side S2, and a large diameter section 23 formed in a straight barrel shape at the rear end side S2 of the tapered section 22. The rear end of the insulating tube 20 forms a head section H that is placed inside the electric power equipment. Here, the rear end of the insulating tube 20 means the rear end side S2 of the large diameter section 23, that is, the part that is connected to the large diameter section 23 on the rear end side S2 from the flange section 32 of the shielding metal fitting 30.

By increasing the overall diameter of the insulating tube 20, the surface potential of the polymer sleeve 1 can be easily reduced, but the earthquake resistance and bending load resistance required of the polymer sleeve 1 will decrease. By making the insulating tube 20 have a structure consisting of a small diameter section 21, a tapered section 22, and a large diameter section 23, it is possible to achieve both electrical performance and earthquake resistance and bending load resistance.

The shielding metal fitting 30 has a cylindrical portion 31 that is embedded concentrically with the internal conductor 10 in the large diameter portion 23 of the insulating tube 20, and a flange portion 32 that extends radially outward from the rear end of the cylindrical portion 31. The cylindrical portion 31 has an electric field relaxation function and relaxes the electric field of the polymer sleeve 1. The polymer sleeve 1 is fixed to the electric equipment in an airtight and watertight manner by connecting the flange portion 32 with a connecting member such as a bolt (not shown) while it is placed on the case C of the electric equipment via a sealing member such as an O-ring (not shown).

The polymer coating 40 is made of a material with excellent electrical insulation performance (e.g., a polymeric material such as silicone polymer). The polymer coating 40 is formed to cover the outer periphery of the insulating tube 20 except for the head portion H. In other words, the polymer coating 40 is formed to cover the outer periphery of the insulating tube 20 on the tip side S1 from the flange portion 32 of the shielding metal fitting 30. The polymer coating 40 has a body portion 41 that covers the outer periphery of the insulating tube 20, and a number of umbrella-shaped folds 42 formed on the outer periphery of the body portion 41 at intervals in the longitudinal direction.

In this embodiment, the pleats 42 include small pleats 43, large pleats 44 that protrude radially outward from the body 41 more than the small pleats 43, and extra-large pleats 45 that protrude radially outward from the body 41 more than the large pleats 44. Specifically, the small pleats 43 and the large pleats 44 are alternately formed along the longitudinal direction, and the extra-large pleats 45 are formed in place of the large pleats 44 at specific longitudinal positions.
The protruding length of the large pleats 44 is set, for example, to 1.05 to 1.25 times that of the small pleats 43. The protruding length of the extra-large pleats 45 is set, for example, to 1.05 to 1.25 times that of the large pleats 44. Preferably, the protruding length of the extra-large pleats 45 is set so that the outer diameter of the extra-large pleats 45 is equal to or smaller than the outer diameter of the flange portion 32 of the shielding metal fitting 30. The number and protruding length of the extra-large pleats 45 are set according to the surface leakage distance required for the polymer sleeve 1. The position of the extra-large pleats 45 will be described later.

The electric field relaxation layer 50 is formed of a zinc oxide (ZnO) layer or a high dielectric constant layer. Specifically, for example, the electric field relaxation layer 50 is composed of a zinc oxide layer in which zinc oxide powder is filled in a resin material, or a high dielectric constant layer with a relative dielectric constant of 10 or more, such as rubber filled with a conductive filler such as carbon black. The electric field relaxation layer 50 is formed integrally with the insulating tube 20 by molding on the outer peripheral surface of the large diameter portion 23 of the insulating tube 20. In other words, the electric field relaxation layer 50 is provided along the interface between the large diameter portion 23 of the insulating tube 20 and the polymer coating 40 in the polymer sleeve 1.

Possible methods for providing an electric field relaxation layer 50 at the interface between the large diameter portion 23 of the insulating tube 20 and the polymer coating 40 include forming the electric field relaxation layer 50 so that its outer diameter is the same as the outer diameter of the large diameter portion 23 of the insulating tube 20 so that the electric field relaxation layer 50 does not protrude radially outward, or forming the electric field relaxation layer 50 so that its inner diameter is the same as the outer diameter of the large diameter portion 23 of the insulating tube 20.

In this embodiment, due to the ease of molding the electric field relaxation layer 50, the electric field relaxation layer 50 is formed on the outer periphery of the large diameter portion 23 of the insulating tube 20, as shown in FIG. 1, so that the inner diameter of the electric field relaxation layer 50 is the same as the outer diameter of the large diameter portion 23 of the insulating tube 20. That is, the thickness of the body 41 of the polymer coating 40 is different between the part where the electric field relaxation layer 50 is present and the part where the electric field relaxation layer 50 is not present. Specifically, the thickness of the body 41 of the polymer coating 40 in the part where the electric field relaxation layer 50 is present is thinner than the thickness of the body 41 in the part where the electric field relaxation layer 50 is not present. As a result, when considering the application of the polymer sleeve 1 to high voltages (for example, 110 kV class or higher), the thickness of the body 41 at the position corresponding to the tip 51 of the electric field relaxation layer 50 is thin, so that aerial discharge is likely to occur in the polymer coating 40 near the tip 51 of the electric field relaxation layer 50. However, the polymer sleeve 1 has an extra-large pleat 45 near the tip 51 of the electric field relaxation layer 50, which helps prevent air discharges from occurring.

The longitudinal length of the large diameter portion 23 of the insulating tube 20 is longer than the longitudinal length of the electric field relaxation layer 50. That is, the electric field relaxation layer 50 is located in the large diameter portion 23 of the insulating tube 20. The rear end of the electric field relaxation layer 50 is electrically connected to the shielding metal fitting 30. The electric field relaxation layer 50 is formed on the outer peripheral surface of the large diameter portion 23 of the insulating tube 20, so that the entire layer has the same diameter. By forming the electric field relaxation layer 50 on the large diameter portion 23, the electric field distribution is optimized, and the electrical performance of the polymer sleeve 1 is improved.

Figure 2 shows an example of the arrangement of the extra-large pleats 45. In Figure 2, the vicinity of the tip of the electric field relaxation layer 50 in the polymer sleeve 1 and the vicinity of the flange portion 32 of the shielding metal fitting 30 are shown in enlarged form.

2, the first extra-large pleat 451, which is an example of the extra-large pleat 45, is located near the tip side S1 of the tip 51 of the electric field relaxation layer 50. In the polymer sleeve 1, the tip 51 of the electric field relaxation layer 50 is prone to electric field concentration and discharge. Therefore, the discharge generated in the low potential part of the rear end side S2 of the polymer sleeve 1 tries to connect between the high potential part of the tip side S1 and the low potential part of the rear end side S2 via the surface corresponding to the tip 51 of the electric field relaxation layer 50. Here, the low potential part of the rear end side S2 of the polymer sleeve 10 means, for example, a bolt (not shown) for attaching the shielding metal fitting 30. In addition, the high potential part of the tip side S1 of the polymer sleeve 10 means, for example, a metal fitting such as a terminal (not shown) attached to the tip 11 of the internal conductor 10. In this embodiment, the first extra-large fold 451 is disposed near the tip side S1 of the tip 51 of the electric field relaxation layer 50, thereby obtaining a so-called barrier effect that suppresses the connection of discharges that occur between low potential parts and high potential parts. Here, the discharges that are suppressed by the barrier effect include both discharges from low potential parts to high potential parts and discharges from high potential parts to low potential parts.

Here, "near the tip side S1" refers to any of the positions of the first to third pleats toward the tip side S1, based on the position corresponding to the tip 51 of the electric field relaxation layer 50 in the polymer coating 40, that is, any position where a barrier effect can be obtained by the first extra-large pleats 451, and preferably refers to the position P1 of the first pleat or the position P2 of the second pleat toward the tip side S1, based on the outer circumferential position corresponding to the tip 51 of the electric field relaxation layer 50 as the reference P0. In FIG. 2, the first extra-large pleats 451 are located at the position P1 of the first pleat.

The second extra-large pleat 452, which is another example of the extra-large pleat 45, is disposed on the rear end side S2 from the tip of the cylindrical portion 31 of the shielding metal fitting 30 where the electric field is concentrated. In the embodiment, the second extra-large pleat 452 is disposed near the flange portion 32 of the shielding metal fitting 30 in the polymer sleeve 1. In FIG. 2, the second extra-large pleat 452 is disposed at the position of the second pleat from the flange portion 32. By disposing the second extra-large pleat 452 near the flange portion 32, the discharge generated in the low potential portion of the rear end side S2 of the polymer sleeve 1 is less likely to be connected to the discharge generated near the tip portion 51 of the electric field relaxation layer 50.

The polymer sleeve 1 also has a third extra-large pleat 453 as the extra-large pleat 45, which is disposed at a position different from the first extra-large pleat 451 and the second extra-large pleat 452. The third extra-large pleat 453 is disposed, for example, at a predetermined interval on the tip side S1 of the first extra-large pleat 451. In this embodiment, two third extra-large pleats 453 are disposed between the tip of the polymer sleeve 1 and the first extra-large pleat 451. Specifically, the third extra-large pleats 453 are disposed on the tip side S1 and the rear end side S2 of the small diameter portion 21 of the polymer sleeve 1, respectively. By providing the third extra-large pleat 453, it becomes easier to ensure the surface leakage distance required for the polymer sleeve 1 without increasing the effective insulation length. Here, the effective insulation length refers to the longitudinal length of the portion where the pleats 42 of the polymer sleeve 1 are formed. In addition, when the third extra-large pleats 453 are disposed near the high potential portion of the tip side S1 of the polymer sleeve 1, the progress of discharge from the high potential portion is suppressed, which is effective in preventing surface flashover.

Thus, the polymer sleeve 1 comprises a rod-shaped inner conductor 10 disposed at the center, a hard insulating tube 20 integrally formed on the outer periphery of the inner conductor 10, a shielding metal fitting 30 embedded in the insulating tube 20 concentrically with the inner conductor 10, a polymer coating 40 having a body 41 covering the outer periphery of the insulating tube 20 and a plurality of umbrella-shaped folds 42 formed on the outer periphery of the body 41 at intervals in the longitudinal direction, and an electric field relaxation layer 50 composed of a zinc oxide layer or a high dielectric constant layer, disposed along the interface between the insulating tube 20 and the polymer coating 40, and having a rear end connected to the shielding metal fitting 30. The multiple pleats 42 include small pleats 43, large pleats 44 that protrude radially from the body 41 more than the small pleats 43, and extra-large pleats 45 that protrude radially from the body 41 more than the large pleats 44. The extra-large pleats 45 include a first extra-large pleat 451 that is located at any one of the first to third pleats toward the tip side S1, based on a position P0 that corresponds to the tip 51 of the electric field relaxation layer 50 in the polymer coating 40.

The barrier effect of the first extra-large pleats 451 suppresses the progress of air discharge occurring between the low potential part and the high potential part of the polymer sleeve 1, making it difficult for surface flashover to occur, improving the insulation characteristics. Here, the insulation characteristics are, for example, dry AC flashover characteristics, water-injected AC flashover characteristics, and artificially contaminated AC withstand voltage characteristics. In addition, by providing the first extra-large pleats 451, the surface leakage distance can be easily increased compared to the case where only the small pleats 43 and the large pleats 44 are arranged. Therefore, it is possible to achieve even higher voltages, and for example, it is possible to support voltage classes of 110 kV or more. In addition, it is possible to comply with the recently revised JEC-5202 standard without significantly changing the design of conventional polymer sleeves.

Furthermore, in the polymer sleeve 1, it is more preferable that the first extra-large pleat portion 451 is positioned at the first position P1 or the second position P2 toward the tip side S1, based on the position P0 corresponding to the tip portion 51 of the electric field relaxation layer 50.
This ensures that the barrier effect provided by the first extra-large pleat 451 is obtained.

In addition, in the polymer sleeve 1 , the oversized pleat 45 further includes a second oversized pleat 452 disposed near the shielding metal fitting 30 .
This makes it difficult for the discharge generated in the low potential portion on the rear end side S2 of the polymer sleeve 1 to be connected to the discharge generated in the vicinity of the front end portion 51 of the electric field relaxation layer 50, thereby further improving the insulation performance.

In addition, in the polymer sleeve 1 , the oversized pleat portion 45 further includes a third oversized pleat portion 453 that is disposed at a position different from the first oversized pleat portion 451 and the second oversized pleat portion 452 .
This makes it possible to ensure the required surface leakage distance without making the protruding length of the extra-large pleats 45 extremely large.

In the polymer sleeve 1, the extra-large pleats 45 are disposed between adjacent small pleats 43. That is, in the longitudinal direction of the polymer sleeve 1, the small pleats 43, the extra-large pleats 45, and the small pleats 43 are disposed in this order.
As a result, the extra-large pleats 45 and the small pleats 43 are adjacent to each other in the longitudinal direction, and bridging due to falling water droplets is less likely to occur during rainfall or when water is poured in, thereby further improving the water-pouring AC flashover characteristics.

In addition, the polymer sleeve 1 and the polymer sleeve 3 described later have a completely dry solid insulation structure. That is, it is an environmentally friendly technology that does not use insulating oil or _SF6 gas inside the sleeve body like the conventional porcelain sleeve. In addition, it is more earthquake-resistant and resistant to disasters than the porcelain sleeve. Therefore, it is possible to contribute to Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization and promote innovation" and Goal 11 "Make cities and human settlements inclusive, safe, resilient and sustainable" of the Sustainable Development Goals (SDGs). Here, the Sustainable Development Goals (SDGs) are international goals that aim for a sustainable and better world by 2030, as described in the "2030 Agenda for Sustainable Development" adopted at the United Nations Summit in September 2015.

The invention made by the inventor has been specifically described above based on the embodiment, but the invention is not limited to the above embodiment and can be modified without departing from the gist of the invention.

For example, in the embodiment, the polymer sleeve of the present invention is described as being applied to an equipment bushing, but the polymer sleeve of the present invention can also be applied to a wall-penetrating bushing (see Patent Document 2) or a cable termination connection part (see FIG. 3) where a cable terminal is attached to the rear end side S2 of the insulating tube 20. Here, the cable terminal includes connecting parts such as a power cable 61, a stress cone 62, and a compression device 63.

Figure 3 is a partial cross-sectional view showing the overall structure of a polymer sleeve 3 to which the present invention is applied to a cable end connection part. That is, the polymer sleeve 3 shown in Figure 3 is a so-called air end connection part. The structure of the air side of the polymer sleeve 3 shown in Figure 3, i.e., the structure of the part having the polymer coating 40, is the same as the structure of the air side of the polymer sleeve 1 of the embodiment, i.e., the structure of the part having the polymer coating 40, so detailed description will be omitted. In addition, as a cable end connection part, there is a so-called inner cone type (see Figure 3) in which a stress cone 62 is housed in an insulating tube 20, and a so-called outer cone type (not shown) in which a polymer sleeve and a cable terminal are connected by covering the outer periphery of an insulating unit with a rubber block as in the insulation method of RBJ (Rubber Block Joint), but the present invention can be applied to either.

For example, in the embodiment, four extra-large pleats 45 are provided, but the number of extra-large pleats 45 is not limited to this, and may be set according to the surface leakage distance required for the polymer sleeve 1. However, if the number of extra-large pleats 45 is increased too much, the interval between the extra-large pleats 45 in the longitudinal direction becomes closer, making flashover more likely. Specifically, if the interval between the extra-large pleats 45 becomes closer, the distance between the tips of the extra-large pleats 45 becomes closer, making it easier for rainwater to run down the tips, making flashover more likely. For this reason, in the polymer sleeve 1 in which small pleats 43 and large pleats 44 are alternately formed in the longitudinal direction as in the embodiment, it is preferable to form extra-large pleats 45 instead of large pleats 44 at specific locations in the longitudinal direction.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

LIST OF SYMBOLS 1, 3 Polymer sleeve 10 Inner conductor 20 Insulating tube 21 Small diameter section 22 Tapered section 23 Large diameter section 30 Shielding metal fitting 31 Cylindrical section 32 Flange section 40 Polymer coating 41 Body section 42 Pleated section 43 Small pleated section 44 Large pleated section 45 Extra large pleated section 451 First extra large pleated section 452 Second extra large pleated section 453 Third extra large pleated section 50 Electric field relaxation layer 61 Power cable 62 Stress cone 63 Compression device C Case H Head section P0 Position corresponding to the tip of the electric field relaxation layer of the polymer sleeve P1 Position of the first pleated section of the polymer sleeve P2 Position of the second pleated section of the polymer sleeve S1 Tip side of the polymer sleeve S2 Rear end of polymer sleeve

Claims (5)

A rod-shaped inner conductor disposed at the center;
a hard insulating tube integrally formed on the outer periphery of the inner conductor;
a shielding metal fitting embedded in the insulating tube concentrically with the inner conductor;
a polymer covering having a body portion covering an outer periphery of the insulating tube and a plurality of umbrella-shaped pleats formed at intervals in a longitudinal direction on the outer periphery of the body portion;
an electric field relaxation layer, which is made of a zinc oxide layer or a high dielectric constant layer, is disposed along the interface between the insulating tube and the polymer coating, and has a rear end connected to the shielding metal fitting;
The plurality of pleats include a plurality of small pleats, a plurality of large pleats arranged alternately with the plurality of small pleats in the longitudinal direction and having a greater protruding length from the body than the small pleats, and extra-large pleats arranged between adjacent small pleats in place of some of the plurality of large pleats and having a greater protruding length from the body than the large pleats,
The extra-large pleat portion includes a first extra-large pleat portion disposed at any one of the first to third sheets toward the tip side based on a position corresponding to the tip of the electric field relaxation layer in the polymer cover,
The first oversized fold is located distally of the reference point.
Polymer sleeve. The first extra-large pleat is disposed at either the first or second position toward the tip side based on a position corresponding to the tip of the electric field buffer layer.
The polymeric sleeve of claim 1. The extra-large pleat further includes a second extra-large pleat arranged on the rear end side of the front end of the shielding metal fitting,
3. The polymer sleeve according to claim 1 or 2 . The oversized pleat further includes a third oversized pleat disposed at a position different from the first oversized pleat and the second oversized pleat.
The polymeric sleeve of claim 3 . the insulating cylinder has a small diameter portion formed in a straight barrel shape, a tapered portion that gradually expands in diameter from the small diameter portion toward a rear end side, and a large diameter portion formed in a straight barrel shape on the rear end side of the tapered portion,
the tip portion of the electric field relaxation layer is located in the large diameter portion,
The first oversized pleat portion and the second oversized pleat portion are disposed on the large diameter portion, and the third oversized pleat portion is disposed on the small diameter portion.
The polymeric sleeve of claim 4 .

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