Power cable termination structure

Abstract

It provides a power cable termination structure that relieves stress associated with the expansion and contraction of the power cable due to heat, etc., relieves the electric field at the termination of the power cable, and also makes it difficult for the insulating fluid to leak from the insulator. The end structure (1) of the power cable (2) comprises: a tube (3) in which the end portion (20) of the power cable (2) is received and in which an insulating fluid is filled; a metal lower flange portion (4) having a through hole (40) into which the end portion (20) is inserted; a metal tube (5) capable of sliding movement relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2) while the through hole (40) is sealed; a seal structure portion (6) that seals the upper portion (5a) of the metal tube (5) and the peeled portion of the outer semiconducting layer (23); a buffer layer (7) that covers the peeled portion of the outer semiconducting layer (23) located on the end portion (2a) side relative to the seal structure portion (6); and a metal layer (8) that covers the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5), wherein the metal tube (5) and the lower flange portion (4) It is grounded through the wire (51).

Description

Technology Field

[0001] The present invention relates to a termination structure of a power cable. Background Technology

[0002] In the termination section of power cables, such as high-voltage power cables, the conductor or outer semiconducting layer is exposed in stages from the leading end; therefore, an insulating tube filled with an insulating fluid is provided to cover the exposed area of ​​the conductor and outer semiconducting layer. Furthermore, to improve withstand voltage characteristics, it is necessary to perform termination treatment at the termination section of the power cable to prevent electric field concentration. An example of such a cable termination structure is the use of a stress cone.

[0003] However, when a power cable having such a termination is energized, the power cable heats up and undergoes thermal expansion, causing it to elongate. Consequently, stress is applied to components such as the parts sealing the insulating fluid at the upper and lower ends of the cable or the stress cone installed at the termination, which may shorten their lifespan.

[0004] In this regard, as a power cable termination structure using a conduit, for example, Patent Document 1 describes a power cable termination structure comprising a cylindrical cover member installed at a position corresponding to a through hole of a base portion on the outer surface of the power cable, a seal member such as a ring that seals between the outer surface of the cover member and the inner surface of the through hole, and a protruding member that protrudes radially outward from a portion disposed within the conduit on the outer surface of the cover member.

[0005] In this termination structure, the cover member is configured to follow the expansion and contraction of the cable while maintaining the interior of the insulator in a sealed state, and the lower end of the insulator is sealed by the base part and the seal member. In addition, near the upper end of the cover member, a seal structure made of insulating material is installed to cover at least from the outer surface of the conductive part of the stress cone to the outer surface of the cover member so as not to intrude into the side of the power cable with the insulating fluid filled in the insulator. Prior art literature

[0006] Japanese Patent Publication No. 2020-182270 The problem to be solved

[0007] However, in the termination structure described in Patent Document 1, the space between the cover member and the base part is sealed with a seal member such as a ring, and the space between the cover member and the power cable is sealed with a seal structure made of an insulating material, and since both are sealed with materials that do not have conductivity, the stress cone and the cover member are not grounded. Therefore, in the termination connection structure of Patent Document 1, when the power cable is energized, the electric field is disrupted due to charging, etc., so there is a possibility that the lifespan of the termination connection part will be shortened.

[0008] The present invention aims to provide a power cable termination structure that relieves stress associated with the expansion and contraction of the power cable due to heat, etc., relieves the electric field at the termination of the power cable, and also makes it difficult for the insulating fluid to leak from the insulator. means of solving the problem

[0009] The gist of the present invention for achieving the above objective is as follows.

[0010] (1) A power cable end structure having a power cable end portion formed by peeling the outer semiconducting layer, the insulation layer, and the conductor sequentially so as to be exposed toward the end side of the power cable having at least a conductor, an insulation layer covering the conductor, and an outer semiconducting layer covering the insulation layer, the power cable end portion having a lower flange portion made of metal having a through hole for inserting the power cable end portion, a metal tube capable of sliding movement relative to the lower flange portion in response to the expansion and contraction of the power cable while the through hole of the lower flange portion is sealed, an upper portion of the metal tube, a seal structure portion that seals the peeled portion of the outer semiconducting layer of the power cable corresponding to the upper portion of the metal tube, a conductive buffer layer covering the peeled portion of the outer semiconducting layer located toward the end side of the seal structure portion, and a metal layer covering the outer surface of the buffer layer and at least the upper portion of the metal tube, and the metal tube and the lower A power cable termination structure characterized by the flange portion being grounded through a conductor.

[0011] (2) The above buffer layer is a single layer, the termination structure of the power cable described in (1).

[0012] (3) The above buffer layer is formed by wrapping a semiconducting tape around the peeled portion of the outer semiconducting layer, in the power cable termination structure described in (1) or (2).

[0013] (4) The upper portion of the buffer layer is a power cable end structure described in (3), wherein the cut line at the top of the semiconducting tape is generally parallel to the extension direction of the power cable.

[0014] (5) The metal layer is formed by wrapping a metal tape over a range from the outer surface of the buffer layer to the outer surface below the upper end of the metal tube, in a power cable termination structure as described in any one of (1) to (4).

[0015] (6) The metal layer is a power cable termination structure described in (5), in which the metal tape is wound starting from a position below the upper position of the metal layer and then wound up to the upper position, and then wound in a direction toward the upper part of the metal tube to cover the starting end of the winding of the metal tape.

[0016] (7) The metal layer is formed by winding a metal tape with braided metal wires, which is the termination structure of the power cable described in (5) or (6).

[0017] (8) The metal layer has a wrap winding structure formed by winding the metal tapes in a partially overlapping state, and the winding end of the metal tape is located on the outer surface of the metal tube, the power cable termination structure described in any one of (5) to (7).

[0018] (9) The metal layer has a solder joint that fixes at least one end of the winding start end and the winding end of the metal tape, and is a power cable termination structure described in any one of claims (5) to (8).

[0019] (10) The above solder joints are spaced apart at multiple locations in the direction of extension of the power cable of the metal layer, and are the power cable termination structure described in (9).

[0020] (11) The metal layer forms the outermost layer of the end portion of the power cable, the end structure of the power cable described in any one of (1) to (10).

[0021] (12) A power cable end structure having a power cable end portion formed by peeling the power cable such that the outer semiconducting layer, the insulation layer, and the conductor are sequentially exposed toward the end portion of the power cable having at least a conductor, an insulation layer covering the conductor, and an outer semiconducting layer covering the insulation layer, the power cable end portion having a lower flange portion made of metal having a through hole for inserting the power cable end portion, a metal tube capable of sliding movement relative to the lower flange portion in response to the expansion and contraction of the power cable while the through hole of the lower flange portion is sealed, an upper portion of the metal tube, a seal structure portion that seals the peeled portion of the outer semiconducting layer of the power cable corresponding to the upper portion of the metal tube, a conductive buffer layer covering the peeled portion of the outer semiconducting layer located toward the end portion of the seal structure portion, and a stress portion installed at the boundary between the insulation layer and the outer semiconducting layer of the power cable and composed of an insulation portion and a semiconducting portion. A power cable termination structure characterized by having a cone, wherein the semiconducting portion of the stress cone and the lower flange portion are grounded by a conductor. Effects of the invention

[0022] According to the present invention, a power cable termination structure can be provided that relieves stress associated with the expansion and contraction of the power cable due to heat, etc., relieves the electric field at the termination portion of the power cable, and also makes it difficult for the insulating fluid to leak from the insulator. Brief explanation of the drawing

[0023] FIG. 1(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to a first embodiment of the present invention, and FIG. 1(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 1(a). FIG. 2 is a drawing showing the state of a buffer layer formed by removing a conduit or metal layer, etc., from the terminal structure of a power cable according to the first embodiment of the present invention and wrapping a semiconductive tape. FIG. 3 is a drawing showing the state of a metal layer formed by removing the conduit, etc. from the end structure of a power cable according to the first embodiment of the present invention and wrapping a metal tape. FIG. 4(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to a second embodiment of the present invention, and FIG. 4(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 4(a). FIG. 5(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to a third embodiment of the present invention, and FIG. 5(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 5(a). Specific details for implementing the invention

[0024] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, the present invention is not limited to the following embodiments, and various modifications are possible within the scope of not altering the essence of the present invention.

[0025] [First embodiment]

[0026] FIG. 1(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to the first embodiment of the present invention, and FIG. 1(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 1(a). FIG. 2 is a drawing showing the state of a buffer layer formed by wrapping a semiconducting tape after removing the insulator or metal layer, etc., from the end structure of a power cable according to the first embodiment of the present invention. FIG. 3 is a drawing showing the state of a metal layer formed by wrapping a metal tape after removing the insulator, etc., from the end structure of a power cable according to the first embodiment of the present invention.

[0027] The end structure (1) of the power cable (2) of the present invention, as shown in FIG. 1, has a power cable (2) end portion (20) formed by peeling off the outer semiconducting layer (23), the insulating layer (22), and the conductor (21) so that they are sequentially exposed toward the end portion (2a) of the power cable (2), which has at least a conductor (21), an insulating layer (22) covering the conductor (21), and an outer semiconducting layer (23) covering the insulating layer (22); the end portion (20) of the power cable (2) is received in a tube (3) in which an insulating fluid is filled inside, and a metal lower flange portion (4) having a through hole (40) for inserting the end portion (20) of the power cable (2), and a lower flange portion (4) capable of sliding movement relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2) while the through hole (40) of the lower flange portion (4) is sealed. The device is equipped with a metal tube (5), a seal structure (6) that seals the upper portion (5a) of the metal tube (5) and the peeled portion of the outer semiconducting layer (23) of the power cable (2) corresponding to the upper portion (5a) of the metal tube (5), a conductive buffer layer (7) that covers the peeled portion of the outer semiconducting layer (23) located on the end (2a) side of the seal structure (6), and a metal layer (8) that covers the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5), and the metal tube (5) and the lower flange portion (4) are grounded through a conductor (51).

[0028] In the terminal structure (1) of the present embodiment, since the metal tube (5) slides relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2), the stress on the terminal structure (1) caused by the expansion and contraction of the power cable can be relieved. In addition, a conductive buffer layer (7) is installed to cover the peeled portion of the outer semiconducting layer (23), and a metal layer (8) is installed to cover the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5). Furthermore, by grounding the metal tube (5) and the lower flange portion (4) with a conductor (51), the buffer layer (7) installed on the outer semiconducting layer (23) becomes grounded, thereby relieving the electric field at the terminal portion (20) of the power cable (2). In addition, the inner surface of the through hole (40) of the lower flange portion (4) of the insulator (3) is sealed by the outer surface of the metal tube (5), and the space between the upper portion (5a) of the metal tube (5) and the outer semiconducting layer (23) of the power cable (2) inside it is sealed by the seal structure portion (6), so even if the metal tube (5) slides relative to the lower flange portion (4), it is difficult to prevent leakage of insulating fluid from the insulator (3).

[0029] Accordingly, by using this termination structure (1), it is possible to provide a termination structure of a power cable (2) that relieves stress associated with the expansion and contraction of the power cable (2) due to heat, etc., relieves the electric field at the termination portion (20) of the power cable (2), and also makes it difficult for the insulating fluid from the insulator (3) to leak.

[0030] The end structure (1) of the power cable (2) of the present embodiment has, as shown in FIG. 1, a power cable (2), a conduit (3), a lower flange portion (4), a metal tube (5), a seal structure portion (6), a buffer layer (7), and a metal layer (8).

[0031] (Power cable)

[0032] The power cable (2) has at least a conductor (21), an insulating layer (22) covering the conductor (21), and an outer semiconducting layer (23) covering the insulating layer (22). Here, the power cable (2) may have a shielding layer (24) formed on the outer surface of the outer semiconducting layer (23) with copper tape or the like and electrically grounded. Additionally, the power cable (2) may have a cable sheath (25) that serves as the outermost layer on the outer surface of the outer semiconducting layer (23) or the shielding layer (24). The power cable (2) may have an inner semiconducting layer between the conductor (21) and the insulating layer (22) (not shown).

[0033] Here, the power cable (2) can be a CV cable, and, for example, can be a high-voltage cable or an ultra-high-voltage cable through which power is transmitted at a transmission voltage of 66 kV or higher. In particular, the power cable (2) may include an ultra-high-voltage cable with a transmission voltage of 400 kV or higher or 500 kV or higher.

[0034] The conductor (21) of the power cable (2) is typically installed in the center of the power cable (2) and serves as a path for the flow of power. The insulating layer (22) is a layer that covers the conductor (21) and is a layer that electrically insulates the conductor (21) from the outer semiconducting layer (23) described later. Additionally, the outer semiconducting layer (23) is a layer configured to cover the insulating layer (22) and shields the electric field generated when the power cable (2) is energized.

[0035] As the material of the conductor (21), a conductive metal, such as copper or aluminum, may be used. Additionally, as the material of the insulating layer (22), an electrically insulating resin, such as cross-linked polyethylene, may be used. Additionally, as the material of the outer semiconducting layer (23) and the inner semiconducting layer, a semiconducting resin may be used. Additionally, as the shielding layer (24), a tape or braided wire made of a conductive metal, such as copper or aluminum, may be used. Additionally, as the material of the cable sheath (25), polyethylene resin may be used, for example.

[0036] The power cable (2) has a power cable (2) formed by peeling off the outer semiconducting layer (23), the insulating layer (22), and the conductor (21) so that they are sequentially exposed toward the end (2a) side. Accordingly, the conductor (21) can be easily connected to a conductive member such as a conductor pull-out rod (33) inside the conduit (3), and when the end (20) of the power cable (2) is covered with a buffer layer (7) described later, the conductor (21) and the outer semiconducting layer (23) can be easily electrically connected while ensuring electrical insulation between the conductor (21) and the outer semiconducting layer (23).

[0037] The material of the power cable (2) is not specifically limited and is determined according to the required current carrying capacity, rated voltage, and the amount of heat that may be generated in the terminal structure (1) of the power cable (2).

[0038] (Aegwan)

[0039] The insulator (3) accommodates the end portion (20) of the power cable (2) and is filled with insulating fluid inside. As a result, the peeled portion of the conductor (21), insulating layer (22), and outer semiconducting layer (23) constituting the end portion (20) of the power cable (2) is covered by the insulator (3), and since insulating fluid is filled around the peeled portion, the end portion (20) of the power cable (2) can be protected.

[0040] The material of the insulator (3) is not particularly limited as long as it is an insulating material, and examples include ceramic, porcelain, glass, rubber, and plastic such as fiber reinforced plastic (FRP). As an example of the insulator (3), it may be constructed by a hollow ordinary housing body (31) made of fiber reinforced plastic (FRP) as shown in FIG. 1, and the surroundings may be covered with a corrugated outer layer (32) of rubber or plastic.

[0041] The insulator (3) forms an internal space (S) together with the upper conductor fixing part (34) and lower flange part (4) described later, and an insulating fluid is filled into the internal space (S). Here, the insulating fluid filled into the internal space (S) is not particularly limited, but, for example, insulating oil such as silicone oil or insulating gas such as SF6 (sulfur hexafluoride) gas can be filled. To prevent leakage of the insulating fluid from the insulator (3), the upper opening (31a) and the lower opening (31b) of the housing body (31) of the insulator (3) are each sealed.

[0042] (Upper conductor fixing part)

[0043] The end structure (1) may have an upper conductor fixing part (34) to which a conductive conductor pull-out rod (33) can be attached to seal an upper opening (31a) in the housing body (31) of a conventional insulator (3). At this time, the conductor pull-out rod (33) is configured to fix the end (2a) of the conductor (21) and to be conductive with the outside of the insulator (3) (upper side of FIG. 1).

[0044] Here, the end (2a) of the conductor (21) is fixed to one side (lower side in FIG. 1) of the conductor withdrawal rod (33) by compression connection, etc. Additionally, the other side (upper side in FIG. 1) of the conductor withdrawal rod (33) is withdrawn to the outside of the insulator (3) from the upper conductor fixing part (34). At this time, since the conductor withdrawal rod (33) is fixed to the upper conductor fixing part (34), the conductor (21) is fixed to the insulator (3) through the conductor withdrawal rod (33).

[0045] The upper conductor fixing part (34) is formed by a plate-shaped member through which, for example, a conductor drawing rod (33) is inserted, and is fixed to the insulator (3) by a connecting member such as a screw. In addition, the portion of the upper conductor fixing part (34) through which the conductor drawing rod (33) is inserted, and the portion between the upper conductor fixing part (34) and the housing body (31) of the insulator (3), are configured so that insulating fluid does not leak, and thus, it is preferable to place a seal member in these portions.

[0046] Additionally, the end structure (1) may not have an independent upper conductor fixing part (34), and may be integrally molded with, for example, the insulator (3).

[0047] (Lower flange section)

[0048] A lower flange portion (4) having a through hole (40) for inserting a power cable (2) is provided to seal a lower opening (31b) in the housing body (31) of a conventional tubular tube (3). The end structure (1) of the power cable (2) of this embodiment is provided with a metal lower flange portion (4) having a through hole (40) for inserting the end portion (20) of the power cable (2).

[0049] Here, the lower flange portion (4) is fixed to the inner or outer circumference of the insulator (3) and has a tubular portion (41) fixed to seal the opening (31b) on the lower side of the insulator (3), and a flange portion (42) extending radially inward and outward from the tubular portion (41). The portion of the flange portion (42) extending radially outward from the tubular portion (41) is fixed to a support insulator (43) installed on a support stand (not shown) by a connecting member such as a screw.

[0050] The lower flange portion (4) is made of metal and is electrically grounded by a grounding wire (not shown) installed on the lower flange portion (4). Accordingly, when the metal container (5) electrically connected to the outer semiconducting layer (23) and the lower flange portion (4) are connected by a wire (51), the metal container (5) connected to the lower flange portion (4) can be grounded through the wire (51).

[0051] The opening shape of the through hole (40) of the lower flange portion (4) is not particularly limited as long as the metal tube (5) can be inserted through it. However, in order to make it more difficult for the insulating fluid to leak from the insulator (3) and to facilitate the vertical sliding movement of the metal tube (5) relative to the lower flange portion (4), it is preferable that the shape be generally the same as the external shape of the metal tube (5).

[0052] Additionally, the metal cover (44) may be configured to extend downward from the lower flange portion (4). By doing so, the direction in which the power cable (2) extends is guided downward by the metal cover (44), making it easier to form a corrosion-preventing layer (26), etc., on the lower side of the insulator (3).

[0053] In addition, the term "metallic" in the present disclosure includes, in addition to being composed of metal, being composed of an alloy.

[0054] (Metal container)

[0055] The metal tube (5) is configured to be able to slide relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2) while the through hole (40) of the lower flange portion (4) is sealed. As a result, since the metal tube (5) slides up and down relative to the lower flange portion (4) in conjunction with the thermal expansion of the outer casing (32), even if the outer casing (32) of the insulator (3) thermally expands due to heat generated when the power cable (2) is energized, friction with the insulating fluid inside the insulator (3) can be eliminated, and the generation of forces acting in the up and down direction, such as drag force, can be suppressed.

[0056] Here, the outer surface of the metal tube (5) is configured to be in contact with the inner surface of the through hole (40), and the through hole (40) is sealed by an axial seal such as a ring. In addition, a power cable (2) is inserted into the metal tube (5), and the upper part (5a) of the metal tube (5) and the peeled part of the outer semiconducting layer (23) of the power cable (2) are sealed by a seal structure (6) described later.

[0057] The material of the metal container (5) is metal, such as aluminum, stainless steel, copper, or brass.

[0058] The inner and outer diameters of the metal tube (5) are preferably the same throughout to facilitate sliding movement with respect to the lower flange portion (4), but to prevent falling out of the through hole (40) of the lower flange portion (4), the outer diameter of the upper or lower end of the metal tube (5) may be partially larger. Additionally, to prevent falling out of the through hole (40) of the lower flange portion (4), a stopper defining the range of sliding movement of the metal tube (5) may be installed on the outer surface of the upper or lower end of the metal tube (5) (not shown).

[0059] (Seal structure)

[0060] The seal structure (6) seals the upper portion (5a) of the metal tube (5) and the peeled portion of the outer semiconducting layer (23) of the power cable (2) corresponding to the upper portion (5a) of the metal tube (5). By doing so, the intrusion of the insulating fluid into the inner portion of the metal tube (5) is suppressed, making it difficult for the insulating fluid to leak from the insulator (3) through the metal tube (5).

[0061] It is preferable that the seal structure (6) covers the outer surface of the upper part (5a) of the metal container (5), and that the outer surface of the metal container (5) located below it is not covered by the seal structure (6). As a result, in the area of ​​the outer surface of the metal container (5) where the seal structure (6) is not covered, the outer surface of the metal container (5) and the inner surface of the metal layer (8) described later come into contact, so that the metal layer (8), the buffer layer (7) connected to the metal layer (8), and the outer semiconducting layer (23) can be grounded through the metal container (5) connected to the lower flange part (4).

[0062] As for the seal structure (6), it is preferable that it be composed of a material that can cover both sides of a member with a different outer diameter without a gap, thereby covering both the outer surface of the metal tube (5) and the outer surface of the peeled portion of the outer semiconducting layer (23) without a gap. Examples of such materials include self-fusing tape or heat shrink tubing.

[0063] (Buffer layer)

[0064] The buffer layer (7) is composed of a conductive material and is installed to cover the peeled portion of the outer semiconducting layer (23) located on the end (2a) side of the seal structure (6). As a result, the electric field concentration at the peeled portion of the outer semiconducting layer (23) located on the end (2a) side of the seal structure (6) is alleviated, and the buffer layer (7) is electrically connected to and grounded to the lower flange portion (4) by the metal layer (8) described later, thereby improving the withstand voltage characteristics at the end portion (20) of the power cable (2).

[0065] In particular, the buffer layer (7) is preferably positioned in the range from the lower part (9a) of the stress cone (9) described later to the upper part of the seal structure (6) to further enhance the effect of mitigating electric field concentration in the peeled part of the outer semiconducting layer (23).

[0066] As shown in FIG. 2, the buffer layer (7) preferably has a semiconducting tape layer (71) formed by wrapping a semiconducting tape around the peeled portion of the outer semiconducting layer (23). By doing so, the buffer layer (7) can be easily formed on the peeled portion of the outer semiconducting layer (23). Meanwhile, the buffer layer (7) may be formed using a heat shrink tube or the like.

[0067] Additionally, the buffer layer (7) is preferably a single layer in order not to generate bubbles inside the buffer layer (7). In particular, when the buffer layer (7) is composed of a semiconducting tape layer (71), it is preferable that the semiconducting tape layer (71) be composed of a single layer of semiconducting tape. Here, as a method of forming the semiconducting tape layer (71) by winding the single layer of semiconducting tape constituting the buffer layer (7) onto the peeling portion of the outer semiconducting layer (23), in addition to gap winding, which involves winding the semiconducting tape without overlapping and creating a gap as shown in FIG. 2, interlocking winding, which involves winding the semiconducting tape without overlapping and without a gap, may be used. In particular, in gap winding where a gap is provided to wind the semiconducting tape, in order to prevent interference between the metal tape constituting the metal layer (8) described later and the outer semiconducting layer (23) of the power cable (2), it is preferable that the buffer layer (7) be composed of a semiconducting tape layer (71) wound with a gap of 5 mm or less along the extension direction X of the power cable (2) when the tape thickness of the semiconducting tape is generally 0.5 mm or more and 1.0 mm or less.

[0068] When the buffer layer (7) is composed of a semiconducting tape layer (71), the upper portion (7a) of the buffer layer (7) preferably has a cut line (7b) at the top of the semiconducting tape that is generally parallel to the extension direction X of the power cable (2), as shown in FIG. 2. At this time, the upper portion (7a) of the buffer layer (7) can be made difficult to peel off because the adhesive area of ​​the semiconducting tape at the upper portion (7a) of the buffer layer (7) is increased by wrapping the semiconducting tape in a horizontal direction (the direction of the cut line when cut perpendicular to the extension direction X) over the peeling portion of the outer semiconducting layer (23) independently of the lower portion, thereby making it difficult to peel off the formed semiconducting tape layer (71). In addition, since the fastening force to the outer semiconducting layer (23) by the semiconducting tape layer (71) at the upper part (7a) of the buffer layer (7) is strengthened, the intrusion of insulating fluid into the inner part of the buffer layer (7) can be suppressed. Meanwhile, the lower part of the buffer layer (7) can efficiently form the semiconducting tape layer (71) by winding it obliquely with respect to the extension direction X of the power cable (2).

[0069] As the material of the buffer layer (7), a conductive material can be used, for example, a resin mixed with conductive carbon powder can be used. In particular, by composing the buffer layer (7) with resin, it is possible to make the buffer layer (7) follow the thermal expansion of the outer semiconducting layer (23), etc., when current is passed through the power cable (2).

[0070] (metal layer)

[0071] As shown in FIG. 1, the metal layer (8) is installed to cover the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5). By doing so, the buffer layer (7) is electrically connected to and grounded to the lower flange portion (4) through the metal tube (5), thereby improving the withstand voltage characteristics at the end portion (20) of the power cable (2). At this time, the seal structure portion (6) is covered on the outside by the metal layer (8). Here, the metal layer (8) may be installed to cover at least a portion of the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5), and may also be installed to cover a portion of the outer surface of the buffer layer (7) by winding it with a gap along the extension direction X of the power cable (2), for example. Meanwhile, the metal layer (8) may also be installed to cover the entire outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5).

[0072] At this time, it is preferable that the metal layer (8) be installed over a range extending from at least the outer surface of the buffer layer (7) to the outer surface below the upper part (5a) of the metal container (5). More preferably, the metal layer (8) is installed below the position adjacent to the lower part (9a) of the stress cone (9) described later. Additionally, from the perspective of ensuring the installation of the semiconducting part (92) of the stress cone (9), it is preferable that the metal layer (8) be installed so as to be in contact with the lower part (9b) of the semiconducting part (92) of the stress cone (9).

[0073] Here, it is preferable that the metal layer (8) has a metal tape layer (81) formed by winding a metal tape. By configuring the metal layer (8) with the metal tape layer (81), the metal layer (8) can be easily formed on the outer surface of the buffer layer (7), the seal structure (6), or the metal container (5).

[0074] In particular, it is preferable that the metal layer (8) be formed by winding a metal tape in which metal wires are braided to form a metal tape layer (81). In this way, by using a metal tape in which metal wires are braided, the fastening force to the buffer layer (7) by the metal tape layer (81) is strengthened, thereby increasing the contact state between the metal layer (8) and the buffer layer (7). Furthermore, by using a metal tape in which metal wires are braided, when assembling the end structure (1), even if air bubbles are contained in the inner surface of the metal layer (8), the air bubbles can easily escape from between the metal wires constituting the metal layer (8), so partial discharge in the high electric field area, particularly near the stress cone (9), can be suppressed, and as a result, the insulation performance of the end structure (1) can be increased.

[0075] When the metal layer (8) has a metal tape layer (81), the metal layer (8) has a wrap-around structure in which the metal tapes are partially overlapped and wound, and it is preferable that the end of the metal tape (81b) is located on the outer surface of the metal tube (5). In particular, since the metal tape layer (81) has a wrap-around structure, even if the power cable (2) expands due to heat generated during power supply, it is difficult to form a gap in the metal layer (8), so the shielding performance of the end structure (1) of the power cable (2) can be improved.

[0076] Additionally, when the metal layer (8) has a metal tape layer (81), it is preferable that the metal layer (8) covers the starting end (81a) of the metal tape by winding the metal tape starting from a position below the top position of the metal layer (8) as shown in FIG. 3, winding it up to the top position, and then winding it in a direction toward the top part (5a) of the metal container (5). At this time, it is preferable that the metal tape forming the metal tape layer (81) starts winding from the outer surface of the buffer layer (7) located below the bottom part (9a) of the stress cone (9), winds it upwards to cover the entire top part (7a) of the buffer layer (7), and then winds it downwards again to cover the end of the metal tape that started winding, passing through the outer surface of the buffer layer (7) and the seal structure part (6), and ending the winding on the metal surface of the metal container (5) where the seal structure part (6) is not formed. By wrapping the metal tape in this way, it can be made difficult to peel off the ends of the metal tape.

[0077] It is preferable that the metal layer (8) has a solder attachment portion (82) on its outer surface. In particular, when the metal layer (8) is composed of a metal tape layer (81), it is preferable that the metal layer (8) has a solder attachment portion (82) that attaches at least one end of the winding start end (81a) and the winding end end (81b) of the metal tape. By doing so, the end of the metal tape is attached to the metal surface of an adjacent metal tape or metal container (5) by the solder attachment portion (82), making it difficult to peel off the end of the metal tape.

[0078] Here, the solder attachment portion (82) may be formed on the outer surface of the buffer layer (7) for the purpose of reducing thermal stress during power cable (2) operation, or the winding start end (81a) of the metal tape may be attached to the outer surface of the buffer layer (7) as the solder attachment portion (82).

[0079] Additionally, it is preferable that the solder bonding portions (82) exist at multiple locations with a spacing L in the extension direction X of the power cable (2) of the metal layer (8). In particular, by having multiple solder bonding portions (82) at multiple locations on the metal layer (8), the metal layer (8) can be made more difficult to peel off. Here, the spacing (L) of the solder bonding portions (82) is not particularly limited, but can be set to, for example, a range of 20 mm or more and 100 mm or less.

[0080] It is preferable that the metal layer (8) forms the outermost layer of the power cable (2)'s end portion (20), excluding the insulator (3). By doing so, when assembling the end structure (1), even if air bubbles are contained within the inner surface of the metal layer (8), the air bubbles can be easily expelled from the inner surface of the metal layer (8), thereby suppressing partial discharge in the high electric field section, particularly near the stress cone (9), and as a result, the insulation performance of the end structure (1) can be improved.

[0081] (Stress Cone)

[0082] The termination structure (1) of the power cable (2) of the present embodiment may have a termination treatment performed to prevent electric field concentration, etc. from occurring at the boundary portion between the insulating layer (22) and the outer semiconducting layer (23). Accordingly, the termination structure (1) of the present embodiment may have a stress cone (9) composed of an insulating portion (91) and a semiconducting portion (92) at the boundary portion between the insulating layer (22) and the outer semiconducting layer (23), as shown in FIG. 1.

[0083] Here, as an example of a stress cone (9), it may have a conventional semiconducting part (92) made of a semiconducting material that adheres to and covers the outer surface of the outer semiconducting layer (23) of the power cable (2), and a conventional insulating part (91) made of an insulating material that adheres to and covers the portion from the outer surface of the semiconducting part (92) to the outer surface of the insulating layer (22). By installing such a stress cone (9), the electric field concentration at the peeled portion of the outer semiconducting layer (23) is mitigated by the semiconducting part (92), thereby improving the withstand voltage characteristics at the end portion (20) of the power cable (2).

[0084] (ferry)

[0085] In the terminal structure (1) of the power cable (2) of the present embodiment, a conductor (grounding wire) (51) is connected between the metal tube (5) and the lower flange portion (4). At this time, the metal tube (5) and the lower flange portion (4) are grounded through the conductor (51). As a result, the metal tube (5) is connected to the grounded lower flange portion (4) through the conductor (51), and the metal tube (5) is connected to the metal layer (8). Furthermore, since the metal layer (8) is connected to the buffer layer (7) installed on the outer semiconducting layer (23) of the power cable (2), the outer semiconducting layer (23) of the power cable (2) or the buffer layer (7) installed on the outer semiconducting layer (23) can be grounded.

[0086] As for the material of the conductor (51), a conductive metal may be used, and more specifically, copper or aluminum may be used. In addition, the shape of the conductor (51) may be a single wire, but from the perspective of making it easy to handle, it may also be a braided wire.

[0087] It is preferable that the length of the conductor (51) be longer than the straight distance of the connection position of the conductor (51) between the metal tube (5) and the lower flange portion (4) when extended during power cable (2) operation. By doing so, the length of the conductor (51) connected to the metal tube (5) and the lower flange portion (4) is adjusted to a length that does not hinder the sliding movement of the metal tube (5) relative to the lower flange portion (4).

[0088] (etc)

[0089] In this embodiment, the peeled portion of the shielding layer (24) and cable sheath (25) of the power cable (2), located at least below the lower flange portion (4), may be covered with a corrosion-resistant layer (26). Here, the corrosion-resistant layer (26) may be composed of, for example, epoxy resin. The epoxy resin may be impregnated with glass tape or the like and wrapped around the peeled portion of the shielding layer (24) or cable sheath (25) of the power cable (2). Additionally, the corrosion-resistant layer (26) may further be provided with a fastening fixing layer (not shown) made of a heat-shrinkable tube.

[0090] [Second embodiment]

[0091] FIG. 4(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to a second embodiment of the present invention, and FIG. 4(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 4(a). Furthermore, in the following description, the same reference numerals are used for components identical to those in the first embodiment, their descriptions are omitted or simplified, and the differences are mainly described.

[0092] In the termination structure (1) of the power cable (2) in FIG. 1, the metal layer (8) is shown as forming the outermost layer (excluding the insulator (3)) of the termination portion (20) of the power cable (2), but is not limited thereto. For example, as in the termination structure (1A) described in FIG. 4, a metal wire (83), such as a flat copper wire, which has a larger cross-sectional area than the metal wire, may be placed on the outer surface of the metal layer (8) having a metal tape layer (81) formed by winding a metal tape in which metal wires are braided. By placing such a metal wire (83), when a large current flows through the metal layer (8) during a ground fault test, the metal wires of the metal tape layer (81) are not severed, and the current can be continuously flowed through the power cable (2). At this time, the range of locations where the metal wire (83) is installed is preferably from the location corresponding to the upper part (7a) of the buffer layer (7) to the location where the metal surface of the metal container (5) is exposed. Additionally, the metal wire (83) may be joined to the surface of the metal layer (8) along the extension direction X of the power cable (2), or may be wound obliquely with respect to the extension direction X of the power cable (2). The end of the metal wire (83) may be joined to the metal layer (8) by known means such as soldering.

[0093] [Third Embodiment]

[0094] FIG. 5(a) is a cross-sectional view schematically illustrating the end structure of a power cable according to a third embodiment of the present invention, and FIG. 5(b) is an enlarged view of the portion enclosed by the dotted line border of FIG. 5(a). Furthermore, in the following description, components identical to those in the first or second embodiment are given the same reference numerals, their descriptions are omitted or simplified, and the differences are mainly described.

[0095] In the termination structure (1) of the power cable (2) of FIG. 1, an embodiment is shown having a metal layer (8) covering the outer surface of the buffer layer (7) and at least the upper part (5a) of the metal tube (5), but is not limited thereto. For example, as in the termination structure (1B) described in FIG. 5, the lower end of the semiconducting part (92) of the stress cone (9) and the metal tube (5) may be electrically connected by wires (52a, 52b), and the semiconducting part (92) of the stress cone (9) and the lower flange part (4) may be grounded through the metal tube (5) by wires (grounding wires) (51, 52a, 52b).

[0096] That is, the end structure (1B) of the power cable (2) of the present embodiment has a power cable (2) having a power cable (2) having at least a conductor (21), an insulating layer (22) covering the conductor (21), and an outer semiconducting layer (23) covering the insulating layer (22), and a power cable (2) having an end portion (20) formed by peeling so that the outer semiconducting layer (23), the insulating layer (22), and the conductor (21) are sequentially exposed toward the end portion (2a) of the power cable (2); a conduit (3) in which the end portion (20) of the power cable (2) is received and an insulating fluid is filled inside, a metal lower flange portion (4) having a through hole (40) for inserting the end portion (20) of the power cable (2), and a metal tube (5) capable of sliding movement relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2) while the through hole (40) of the lower flange portion (4) is sealed. The device is equipped with a seal structure (6) that seals the upper portion (5a) of the metal tube (5) and the peeled portion of the outer semiconducting layer (23) of the power cable (2) corresponding to the upper portion (5a) of the metal tube (5), a conductive buffer layer (7) that covers the peeled portion of the outer semiconducting layer (23) located on the end portion (2a) side of the seal structure (6), and a stress cone (9) that is installed at the boundary portion between the insulation layer and the outer semiconducting layer of the power cable and is composed of an insulation portion (91) and a semiconducting portion (92), and the semiconducting portion (92) and the lower flange portion (4) of the stress cone (9) are grounded by conductors (51, 52a, 52b).

[0097] In the end structure (B1) of the present embodiment, the conductors (52a, 52b) are wired from the semiconducting portion (92) of the stress cone (9) across the seal structure portion (6) and the buffer layer (7) to a member such as a metal tube (5) grounded to the lower flange portion (4). Since the metal tube (5) can maintain conductivity between the semiconducting portion (92) of the stress cone (9) and the metal tube (5) even when it slides relative to the lower flange portion (4) in response to the expansion and contraction of the power cable (2), the semiconducting portion (92) of the stress cone (9) remains grounded, thereby mitigating the electric field at the end portion (20) of the power cable (2).

[0098] Here, the material of the conductor (52a, 52b) may be a conductive metal, and more specifically, copper or aluminum. In addition, the shape of the conductor (52a, 52b) may be a single wire, but from the perspective of ease of handling, it is preferable to have a braided wire.

[0099] In the end structure (1B) described in FIG. 5, one end of the conductor (52a) is connected to the semiconducting portion (92) of the stress cone (9). Additionally, one end of the conductor (52b) is connected to a member such as a metal tube (5) that is grounded to the flange portion (4). Here, it is preferable to fix the connection portions between the conductors (52a, 52b) and the semiconducting portion (92) or the member grounded to the lower flange portion (4). By doing so, a more reliable electrical connection can be established between the conductors (52a, 52b) and the semiconducting portion (92) or the member grounded to the lower flange portion (4). As means of fixing the conductors (52a, 52b) and the semiconducting portion (92) or the member grounded to the lower flange portion (4), in addition to soldering, fixing by fastening using a binding member may be used. In addition, examples of binding members include metal wire, metal band, metal tape, semiconducting tape, etc.

[0100] Additionally, among the conductors (52a) and (52b), the end that is not connected to a member such as a semiconducting part (92) or a metal tube (5) is preferably configured to be detachable by means of a crimp terminal, etc. Accordingly, when assembling the end structure (B1) to the end portion (20) of the power cable (2), a conductor grounded from the stress cone (9) to the lower flange portion (4) can be easily formed.

[0101] The conductors (52a, 52b) are wired from the semiconducting portion (92) of the stress cone (9) across the seal structure portion (6) and the buffer layer (7) to a member such as a metal tube (5) grounded to the lower flange portion (4). Here, it is preferable that the conductors (52a, 52b) are configured not to come into contact with either or both of the seal structure portion (6) and the buffer layer (7) in order to prevent disconnection caused by sliding movement of the metal tube (5).

[0102] Additionally, the total length of the conductors (52a, 52b) is preferably longer than the straight distance of the connection position of the conductors (52a, 52b) when extended during power cable (2) operation. By doing so, the length of the conductors (52a, 52b) can be adjusted to a length that does not hinder sliding movement relative to the lower flange portion (4) of the metal tube (5).

[0103] In addition, in the termination structure (1B) of the power cable (2) in FIG. 5, the lower end of the semiconducting portion (92) of the stress cone (9) and the metal tube (5) are connected by two conductors (52a, 52b), but this is not limited thereto. For example, the lower end of the semiconducting portion (92) of the stress cone (9) and a member such as the metal tube (5) grounded to the lower flange portion (4) may be connected by one conductor not shown.

[0104] Additionally, in the terminal structure (1B) of the power cable (2) in FIG. 5, a configuration is shown in which the semiconducting portion (92) and the lower flange portion (4) of the stress cone (9) are grounded through the metal tube (5) using conductors (51, 52a, 52b) without installing a metal layer (8), but this is not limited thereto. For example, a configuration may be made such that the semiconducting portion (92) and the lower flange portion (4) of the stress cone (9) are grounded through the metal layer (8) using conductors (51, 52a, 52b) while installing a metal layer (8) that covers the outer surface of the buffer layer (7) and at least the upper portion (5a) of the metal tube (5). That is, the conductors (52a, 52b) may be wired across the seal structure portion (6) and the buffer layer (7) between the semiconducting portion (92) of the stress cone (9) and the metal layer (8). By doing so, the semiconducting portion (92) and the buffer layer (7) of the stress cone (9) can be electrically connected to the lower flange portion (4) through the metal layer (8) or the metal tube (5) to ground them, and as a result, the withstand voltage characteristics at the end portion (20) of the power cable (2) can be improved.

[0105] In this way, when the semiconducting portion (92) and the lower flange portion (4) of the stress cone (9) are grounded through the metal layer (8) by wires (51, 52a, 52b), it is preferable that the wire (52b) be fixed to the metal layer (8) by soldering. At this time, it is preferable that the location where the wire (52a) and the wire (52b) are connected be near the bottom of the semiconducting portion (92) of the stress cone (9). In addition, from the perspective of forming the end structure with fewer processes, it is preferable that the wire (52b) be fixed together with the metal layer (8) to the soldering portion (82) of the metal layer (8).

[0106] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and includes all aspects included in the concept and claims of the present invention, and can be modified in various ways within the scope of the present invention. Explanation of the symbols

[0107] 1, 1A Termination Structure of Power Cables 2 power cables 2a Termination of power cable 20 Termination of power cable 21 conductors 22 Insulation layer 23 External semiconducting layer 24 shielding layers 25 Cable Sheath 26 Anti-corrosion layer 3 Aegwan 31 Housing body 31a Upper opening of the housing body 31b Lower opening of the housing body 32 coat 33 conductor pull-out rod 34 Upper conductor fixing part 4. Lower flange section 40 Through hole in lower flange 41 Tubular part 42 flange section 43 Support Aeja 5 metal containers 5a Top part of the metal container 51 wire (grounding wire) 6 Seal Structure 7 buffer layers 71 Semiconducting tape layer 7a Upper part of the buffer layer 7b Top cut line of the semiconducting tape 8 metal layers 81 Metal tape layer 81a Starting point of winding metal tape 81b Winding end of metal tape 82 Solder bonding part 83 metal wire 9 Stress Cone 9a Bottom part of the stress cone 9b Bottom of the entire peninsula 91 Insulation of the stress cone 92 Stress Cone's Semiconductor Interior space of S Aegwan X Power cable extension direction L Spacing of the solder joint

Claims

Claim 1 A power cable termination structure having a power cable termination portion formed by peeling so that the outer semiconducting layer, the insulating layer, and the conductor are sequentially exposed toward the termination side of the power cable having at least a conductor, an insulating layer covering the conductor, and an outer semiconducting layer covering the insulating layer, the power cable termination structure comprising: a conduit receiving the power cable termination portion and filled with an insulating fluid inside; a metal lower flange portion having a through hole for inserting the power cable termination portion; a metal tube capable of sliding movement relative to the lower flange portion in response to the expansion and contraction of the power cable while the through hole of the lower flange portion is sealed; an upper portion of the metal tube and a seal structure portion sealing a peeled portion of the outer semiconducting layer of the power cable corresponding to the upper portion of the metal tube; a conductive buffer layer covering a peeled portion of the outer semiconducting layer located toward the termination side of the seal structure portion; and a metal layer covering the outer surface of the buffer layer and at least the upper portion of the metal tube, wherein the metal tube and the lower A power cable termination structure characterized by the flange portion being grounded through a conductor. Claim 2 In claim 1, the power cable termination structure, wherein the buffer layer is a single layer. Claim 3 A power cable termination structure according to claim 1 or 2, wherein the buffer layer is formed by wrapping a semiconducting tape around the peeled portion of the outer semiconducting layer. Claim 4 In paragraph 3, the upper portion of the buffer layer is a power cable termination structure in which the cut line at the top of the semiconducting tape is parallel to the extension direction of the power cable. Claim 5 A power cable termination structure according to claim 1, wherein the metal layer is formed by winding a metal tape over a range from at least the outer surface of the buffer layer to the outer surface below the upper end of the metal tube. Claim 6 A power cable termination structure according to claim 5, wherein the metal layer covers the winding start end of the metal tape by winding the metal tape starting from a position below the upper position of the metal layer, winding it up to the upper position, and then winding it in a direction toward the upper part of the metal tube. Claim 7 In claim 5 or 6, the metal layer is a power cable termination structure formed by winding a metal tape in which metal wires are braided. Claim 8 A power cable termination structure according to claim 5 or 6, wherein the metal layer has a wrap winding structure formed by winding the metal tapes in a partially overlapping state, and the winding end of the metal tape is located on the outer surface of the metal tube. Claim 9 In claim 8, the metal layer has a solder attachment portion that attaches at least one of the winding start end and winding end of the metal tape, forming a power cable termination structure. Claim 10 In claim 9, the solder fixing portion is a power cable termination structure that exists at multiple locations spaced apart in the extension direction of the power cable of the metal layer. Claim 11 In claim 1, the metal layer forms the outermost layer of the termination portion of the power cable, a termination structure of the power cable. Claim 12 A power cable termination structure having a power cable termination portion formed by peeling so that the outer semiconducting layer, the insulation layer, and the conductor are sequentially exposed toward the termination side of the power cable having at least a conductor, an insulation layer covering the conductor, and an outer semiconducting layer covering the insulation layer, the power cable termination portion having a conduit that accommodates the power cable termination portion and is filled with an insulating fluid inside, a metal lower flange portion having a through hole for inserting the power cable termination portion, a metal tube capable of sliding movement relative to the lower flange portion in response to the expansion and contraction of the power cable while the through hole of the lower flange portion is sealed, an upper portion of the metal tube, a seal structure portion that seals the peeled portion of the outer semiconducting layer of the power cable corresponding to the upper portion of the metal tube, a conductive buffer layer covering the peeled portion of the outer semiconducting layer located toward the termination side of the seal structure portion, and a stress portion installed at the boundary between the insulation layer and the outer semiconducting layer of the power cable and composed of an insulation portion and a semiconducting portion. A power cable termination structure characterized by having a cone, wherein the semiconducting portion of the stress cone and the lower flange portion are grounded by a conductor.

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