JP2022188918A - Termination structure for power cable, and bushing - Google Patents

Abstract

To provide a termination structure for a power cable of which the insulation strength is improved, and a bushing.SOLUTION: The present invention relates to a termination structure for a power cable comprising: a terminal part of the power cable including a conductor, an insulation layer, an external semiconductor layer and a shield layer successively from the inside; a bushing covering a tip-side portion in the terminal part of the power cable; and a first metal fitting covering a root-side portion in the terminal part of the power cable. The bushing includes a plurality of end faces disposed to be directed to the root side. The plurality of end faces includes: a first face to which a tip portion of the first metal fitting is mounted; a second face to which a second metal fitting for fixing the bushing to a predetermined object is mounted; and a third face disposed between the first face and the second face in such a manner that the first metal fitting and the second metal fitting are disposed separately in a radial direction of the bushing. The third face is disposed closer to the root side than the first face and the second face.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a power cable termination structure and a porcelain tube.

As a termination structure of a power cable, FIG. 11 of Patent Document 1 discloses a termination connection part directly connected to a gas insulated switchgear (GIS). Hereinafter, the terminal connection portion of the power cable shown in FIG. 11 of Patent Document 1 will be referred to as a conventional structure. The above-described conventional structure includes an end portion of a power cable, a stress cone, an insulating porcelain tube, and a cylindrical protective fitting.

The end of the power cable is stripped. Therefore, the end of the conductor, the end of the insulating layer, the end of the outer semi-conductive layer, and the end of the shielding layer are partially exposed in this order from the tip of the terminal of the power cable. The insulating porcelain tube described above covers the tip portion and the stress cone of the terminal portion of the power cable. The protective fitting described above covers the root side portion of the terminal portion of the power cable. Note that the tip side is the conductor side. The root side is the shielding layer side.

The insulating porcelain tube is fixed to the GIS case by bolts via an annular plate-like mounting flange. The mounting flange is arranged in contact with an annular plate-shaped flange provided on the root side of the insulating insulator tube. The protective fitting is electrically connected to the shielding layer.

JP 2005-006424 A

It is desired to improve the insulation strength in a power cable termination structure such as the conventional structure described above. In particular, it is desired to increase the insulation strength between the shielding layer of the terminal portion of the power cable and a fixing metal fitting such as a mounting flange disposed on the root side of the insulating porcelain tube.

An object of the present disclosure is to provide a termination structure for a power cable with excellent insulation strength. Another object of the present disclosure is to provide a porcelain tube capable of constructing a power cable termination structure having excellent insulation strength.

A power cable termination structure according to an aspect of the present disclosure includes a power cable terminal portion having a conductor, an insulating layer, an external semiconductive layer, and a shield layer in order from the inside, and a tip side portion of the power cable terminal portion. and a first metal fitting that covers the root side portion of the terminal portion of the power cable. The porcelain pipe has a plurality of end faces arranged to face the root side. The plurality of end faces include a first surface to which the tip of the first metal fitting is attached, a second surface to which a second metal fitting for fixing the insulator pipe to a predetermined object is attached, and the first metal fitting. A third surface is arranged between the first surface and the second surface so that the second metal fitting is spaced apart in the radial direction of the porcelain insulator. The third surface is arranged closer to the base than the first surface and the second surface.

A porcelain pipe according to an aspect of the present disclosure is a porcelain pipe used in a termination structure of a power cable, and includes a first end portion arranged on a tip side of a terminal portion of the power cable, and a root portion of the terminal portion of the power cable. and a plurality of end faces arranged to face the second end. The plurality of end faces include a first face, a second face arranged radially outward of the insulator pipe from the first face, and a second face arranged between the first face and the second face. It has three sides. The third surface is arranged closer to the second end than the first surface and the second surface.

The power cable termination structure of the present disclosure is excellent in insulation strength. The porcelain tube of the present disclosure can construct a termination structure for a power cable with excellent insulation strength.

FIG. 1 is a partial cross-sectional view showing the termination structure of the power cable of Embodiment 1. FIG. FIG. 2 is an enlarged view showing a portion on the second end side of the insulator in the power cable termination structure of the first embodiment shown in FIG. 1 .

[Description of Embodiments of the Present Disclosure]
In the conventional structure described above, the insulation distance between the shielding layer at the end of the power cable and the fixing metal fitting such as the mounting flange corresponds to the insulation distance between the protective metal fitting and the fixing metal fitting. In the following description, of the two ends of the insulating porcelain tube, the end located on the root side of the terminal portion of the power cable will be referred to as the lower end. The end face on the lower end side is called a lower end face. The flange of the insulating insulator pipe described above extends radially outward of the insulating insulator pipe from the outer peripheral surface of the cylindrical portion forming the portion on the lower end side of the insulating insulator pipe. Further, the flange is provided such that the lower end surface of the cylindrical portion is arranged closer to the lower end than the lower end surface of the flange. These two lower end surfaces are connected by the outer peripheral surface of the cylindrical portion. The protective fitting is attached to the lower end surface of the cylindrical portion. The fixing metal fitting is attached to the lower end surface of the flange of the insulator pipe. Therefore, the insulation distance between the protective metal fitting and the fixing metal fitting is substantially equal to the distance along the longitudinal direction of the insulating porcelain pipe on the outer peripheral surface of the cylindrical portion disposed between the two lower end surfaces. That is, the insulation distance is equal to the length of the straight line connecting the two lower end surfaces with the straight line along the longitudinal direction. Hereinafter, this insulation distance may be referred to as the insulation distance of the conventional structure. The present disclosure proposes a structure having a longer insulation distance than that of the conventional structure described above. First, the contents of the embodiments of the present disclosure will be listed and described.

(1) A power cable termination structure according to an aspect of the present disclosure includes a power cable terminal portion having a conductor, an insulating layer, an external semiconductive layer, and a shield layer in order from the inside, and a tip at the terminal portion of the power cable. A porcelain tube that covers the side portion and a first metal fitting that covers the root side portion of the terminal portion of the power cable. The porcelain pipe has a plurality of end faces arranged to face the root side. The plurality of end faces include a first surface to which the tip of the first metal fitting is attached, a second surface to which a second metal fitting for fixing the insulator pipe to a predetermined object is attached, and the first metal fitting. A third surface is arranged between the first surface and the second surface so that the second metal fitting is spaced apart in the radial direction of the porcelain insulator. The third surface is arranged closer to the base than the first surface and the second surface.

In the power cable termination structure of the present disclosure, the insulation distance between the first metal fitting that functions as the protective metal fitting described above and the second metal fitting that functions as the fixing metal fitting such as the mounting flange described above is the insulation distance of the conventional structure described above. longer than The reason for this will be described later. A shielding layer of a power cable is electrically connected to the first metal fitting. Therefore, in the power cable termination structure of the present disclosure, the insulation distance between the shield layer and the second metal fitting is longer than that in the conventional structure. In this respect, the power cable termination structure of the present disclosure is superior in insulation strength to the conventional structure.

Since the third surface is arranged closer to the root side of the terminal portion of the power cable than the first surface and the second surface, the insulator pipe has a cylindrical portion extending toward the root side from the first surface and the second surface. Prepare. A third surface is an end surface arranged so as to face the root side of the cylindrical portion. The insulating distance between the first metal fitting arranged on the first surface and the second metal fitting arranged on the second surface is the length along the surface of the cylindrical portion including the third surface. For example, if the cylindrical portion is cylindrical, the insulation distance between the first metal fitting and the second metal fitting is the sum of the following three distances. The first distance is the distance along the longitudinal direction of the insulator pipe on the inner peripheral surface of the cylinder. The inner peripheral surface of the cylinder connects the first surface and the third surface. The second distance is the distance along the longitudinal direction on the outer peripheral surface of the cylinder. The outer peripheral surface of the cylinder connects the third surface and the second surface. The third distance is the distance along the radial direction of the insulator pipe on the third surface connecting the inner peripheral surface and the outer peripheral surface. In the conventional structure described above, the first surface and the third surface, so to speak, coincide. Therefore, the insulation distance of the conventional structure is only the second distance, which is shorter than the total value.

(2) As an example of the power cable termination structure of the present disclosure, the porcelain insulator includes a cylindrical tubular portion extending toward the root side from the first surface and the second surface, and the third surface is an end surface of the tubular portion.

The cylindrical portion of the porcelain pipe has a simple shape such as a cylindrical shape. This porcelain pipe is also excellent in manufacturability in that the porcelain pipe has a shape that is easy to form. As will be described later, the length of the cylindrical portion can be easily adjusted.

(3) As an example of the power cable termination structure of (2) above, the first surface and the second surface are arranged at the same position in the longitudinal direction of the insulator.

In the above case, a longer insulation distance can be ensured than when the first surface and the second surface are displaced in the longitudinal direction of the insulator. In this respect, the termination structure of the power cable of the above configuration is further excellent in insulation strength. Moreover, compared with the case where the first surface and the second surface are displaced in the longitudinal direction, the inner space of the cylindrical portion of the insulator is wider. Therefore, the portion of the first metal fitting that is arranged inside the cylindrical portion is large. In this respect, the cylindrical portion easily protects the tip portion of the first metal fitting.

(4) As an example of the power cable termination structure of (3) above, a stress cone covering the end portion of the insulating layer exposed from the outer semi-conductive layer, and the stress cone extending from the root side to the tip side. a pressing metal fitting for pressing the first metal fitting electrically connected to the shielding layer; It is

In the above case, as will be described later, the length of the pressing fitting can be shortened compared to the conventional structure described above. In this respect, the power cable termination structure of the above configuration can be made shorter in length along the longitudinal direction than the above-described conventional structure.

(5) An insulator according to an aspect of the present disclosure is an insulator used for a termination structure of a power cable, and includes a first end disposed on a tip side of a terminal of the power cable, and a terminal of the power cable. and a plurality of end faces arranged to face the second end. The plurality of end faces include a first face, a second face arranged radially outward of the insulator pipe from the first face, and a second face arranged between the first face and the second face. It has three sides. The third surface is arranged closer to the second end than the first surface and the second surface.

When constructing a termination structure of a power cable using the porcelain tube of the present disclosure, the first surface is a surface to which a first metal fitting such as the protective metal fitting described above is attached. The second surface is a surface on which a second metal fitting for fixing the porcelain pipe to a predetermined object such as a GIS case is attached. By doing so, the insulation distance between the first metal fitting and the second metal fitting is longer than the insulation distance of the conventional structure as described above. Such a porcelain tube of the present disclosure can construct a termination structure of a power cable having excellent insulation strength.

[Details of the embodiment of the present disclosure]
Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the figure, the same reference numerals denote the same name. The present invention is not limited to these exemplifications, but is indicated by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

[Embodiment 1]
(overview)
A power cable terminating structure of Embodiment 1 and a porcelain insulator of Embodiment 1 will be described with reference to FIGS. 1 and 2 .
The right part of FIG. 1 shows a cross section obtained by cutting the right half of the power cable termination structure of Embodiment 1 along a plane parallel to the longitudinal direction of the power cable. However, the power cable shows the appearance, not the cross section. Some of the members constituting the termination structure of the power cable, for example, bolts 52, 62, 85, etc., which will be described later, also show the external appearance rather than the cross section. The left part of FIG. 1 shows the appearance of the left half of the power cable termination structure of the first embodiment. FIG. 2 shows an enlarged view of a part of the cross section shown in FIG. Note that the longitudinal direction of the power cable corresponds to the vertical direction in FIGS. 1 and 2, for convenience of explanation, the size and size ratio of each member may differ from the actual size.

A power cable termination structure 1 of Embodiment 1 is provided at a terminal portion 2 of a power cable for connecting the power cable to an external object (not shown). The target object is, for example, a power device installed in a power facility such as a substation facility or a power receiving facility. The power equipment is, for example, a switchgear, a transformer, or the like. The switchgear is for example a gas insulated switchgear (GIS).

The power cable termination structure 1 of Embodiment 1 is directly connected to a gas insulated switchgear (GIS). For the basic configuration of the power cable termination structure 1 of the first embodiment, reference can be made to a known GIS direct connection termination connection portion. First, the basic configuration will be described below.

A power cable termination structure 1 of Embodiment 1 includes a power cable terminal portion 2 , an insulator tube 3 , a stress cone 4 , a first metal fitting 5 , and a pressing metal fitting 8 . The end portion 2 of the power cable is step-stripped. The stress cone 4 is placed on the insulating layer 21 at the end 2 of the power cable. The porcelain tube 3 covers the tip side portion of the terminal portion 2 of the power cable and also covers the stress cone 4 . The first metal fitting 5 is a metal fitting having the function of the protective metal fitting in the conventional structure described above. The first metal fitting 5 includes a tubular body portion 51 . The body portion 51 covers the root side portion of the terminal portion 2 of the power cable. The first metal fitting 5 is electrically connected to the shielding layer 23 of the terminal portion 2 of the power cable. The pressing fitting 8 presses the stress cone 4 from the root side toward the tip side of the terminal portion 2 of the power cable.

The tip side of the terminal portion 2 of the power cable is the conductor 20 side. The root side of the terminal portion 2 of the power cable is the side opposite to the tip side and is the shielding layer 23 side. Hereinafter, the side of each member in the termination structure 1 of the power cable that is the same as the side on which the end portion of the conductor 20 is arranged may be referred to as the tip end side. In the power cable termination structure 1, the side of each member that is the same as the side on which the end portion of the shielding layer 23 is arranged is sometimes referred to as the root side. The tip side is the upper side in FIGS. 1 and 2 . The root side is the lower side in FIGS. The distal end of each member is the end located on the distal end side of each member.

The insulator 3 has a first end 34 and a second end 35 . The first end portion 34 is arranged on the distal end side of the terminal portion 2 of the power cable. The second end portion 35 is arranged on the root side of the terminal portion 2 of the power cable. The porcelain tube 3 has a plurality of end surfaces at the second end 35 arranged to face the root side of the terminal portion 2 of the power cable. The plurality of end surfaces comprise a first surface 31 and a second surface 32 . The second surface 32 is arranged radially outside the insulator 3 than the first surface 31 . A tip portion of the first metal fitting 5 is attached to the first surface 31 . A second metal fitting 6 for fixing the porcelain pipe 3 to a predetermined object is attached to the second surface 32 . The predetermined object in this example is the GIS case 9 . The second metal fitting 6 is a metal fitting having a function of a fixing metal fitting such as a mounting flange in the conventional structure described above. The radial direction of the porcelain pipe 3 corresponds to the lateral direction in FIGS. Moreover, the radial direction of the porcelain tube 3 corresponds to the radial direction of the terminal portion 2 of the power cable.

In particular, the power cable termination structure 1 of the first embodiment includes the porcelain tube 3 of the first embodiment. The porcelain tube 3 of Embodiment 1 has a third surface 33 in addition to the first surface 31 and the second surface 32 as end surfaces arranged on the root side of the terminal portion 2 of the power cable. The third surface 33 is arranged between the first surface 31 and the second surface 32 . The first metal fitting 5 and the second metal fitting 6 are arranged apart from each other in the radial direction of the insulator pipe 3 by such a third surface 33 . Further, the third surface 33 is arranged closer to the base of the terminal portion 2 of the power cable than the first surface 31 and the second surface 32 are. The third surface 33 makes the insulation distance between the first metal fitting 5 functioning as the protective metal fitting and the second metal fitting 6 functioning as the mounting flange longer than the insulation distance of the conventional structure described above.

The members constituting the power cable termination structure 1 will be described in order below.
(Constituent member)
<Power cable>
The power cable has a conductor 20, an insulating layer 21, an outer semi-conductive layer 22, a shielding layer 23 and a sheath 24 in order from the inside. The power cable further comprises an internal semiconducting layer (not shown) inside the insulating layer 21 . A typical example of such a power cable is a cross-linked polyethylene insulated vinyl sheath cable (CV cable). Well-known materials can be used for the constituent materials of the respective members that constitute the power cable.

The power cable of this example is a high-voltage cable with a working voltage of, for example, 66 kV or more and 500 kV or less. The cross-sectional area of the conductor, the thickness of the insulating layer 21, and the like are set according to the working voltage.

By being step-stripped as described above, the ends of the above-described members constituting the power cable are exposed. The terminal portion 2 of the power cable includes an end portion of the shielding layer 23 exposed from the sheath 24, an end portion of the outer semi-conductive layer 22 exposed from the shielding layer 23, and an insulating layer exposed from the outer semi-conductive layer 22. 21 and the end of the conductor 20 exposed from the insulating layer 21 . A tape-wrapped shielding layer is provided between the outer semi-conductive layer 22 and the shielding layer 23 . Metal tapes such as copper mesh tapes, insulating tapes such as polyvinyl chloride (PVC) tapes, and the like are used for the tape-wrapped shielding layer.

A compression sleeve 200 is attached to the end of the conductor 20 . The compression sleeve 200 is fitted in the first electrode portion 38, which will be described later. A conductor lead (not shown) is connected to the first electrode portion 38 . The power cable and the GIS are electrically connected via the first electrode portion 38 and the conductor lead.

<Stress Cone>
The stress cone 4 is a tubular member for relieving electrical stress acting on the cut ends of the outer semiconductive layer 22 . The stress cone 4 of this example has a spindle-shaped outer shape. The stress cone 4 has an insulating tubular portion 41 and a semiconductive portion 42 . The insulating tubular portion 41 covers the end portion of the insulating layer 21 described above. The semiconducting portion 42 is provided on the root side and the inner peripheral side of the insulating cylindrical portion 41 . The semiconducting portion 42 is arranged in contact with the edge of the outer semiconducting layer 22 described above.

A known material can be used for the constituent material of the stress cone 4 . A constituent material of the insulating cylindrical portion 41 is, for example, an electrically insulating rubber. A constituent material of the semiconducting portion 42 is a semiconducting material. The semiconductive material is, for example, a rubber composition containing electrically insulating rubber and a conductive material such as carbon. Since the constituent material includes rubber, the insulating tubular portion 41 can be brought into close contact with the end portion of the insulating layer 21 described above. The semi-conducting portion 42 can adhere to the edge of the outer semi-conducting layer 22 . The stress cone 4 of this example is a molded body in which an insulating tubular portion 41 and a semiconductive portion 42 are integrated.

<Press fitting>
Description of the pressing metal fitting 8 will be made mainly with reference to FIG. The pressing metal fitting 8 of this example uses the biasing force of the spring 83 as the pressing force. A known configuration can be referred to for the basic configuration of such a pressing metal fitting 8 .

The press fitting 8 includes a ring portion 81 , a shaft fitting 82 and a spring 83 . The ring portion 81 is a member that contacts the stress cone 4 and presses the stress cone 4 directly, as shown in FIG. The shaft fitting 82 is a member for adjusting the pressing force, and is typically a bolt. A spring 83 is a member for exerting a pressing force, and is typically a compression spring.

A tip portion of the shaft fitting 82 is fastened to an annular plate-shaped flange fitting 50 to be described later. In this example, a stud bolt 820 is attached to the shaft fitting 82 . The tip of the stud bolt 820 is also fastened to the flange fitting 50 . An intermediate portion of the shaft fitting 82 is fastened to an annular plate-shaped flange fitting 80 . The flange fitting 80 is arranged closer to the base of the terminal portion 2 of the power cable than the flange fitting 50 is. A nut is fastened to the end portion of the shaft fitting 82 that is located closer to the base than the flange fitting 80 . By tightening or loosening this nut, the flange fitting 80 moves along the longitudinal direction of the power cable using the shaft fitting 82 as a guide. The spring 83 is arranged between the ring portion 81 and the flange fitting 80 as shown in FIG. Therefore, the distance between the ring portion 81 and the flange fitting 80 changes as the flange fitting 80 moves as described above. This change causes the amount of compression of the spring 83 to change. The pressing force changes according to the compression amount of the spring 83 . Therefore, the pressing force is adjusted by adjusting the interval.

In this example, a guide rod 84 is arranged inside the spring 83 . Spring 83 expands and contracts along guide rod 84 . A bolt 85 is inserted inside the guide rod 84 . A tip portion of the bolt 85 is fastened to the ring portion 81 . The bolt 85 reliably transmits the pressing force of the spring 83 to the ring portion 81 .

1 and 2 show only one shaft fitting 82, one spring 83, one guide rod 84, and one bolt 85, but in reality there are a plurality of them. A plurality of springs 83 and the like are arranged at predetermined intervals in the circumferential direction of the power cable so as to surround the outer circumference of the power cable. Therefore, a pressing force is applied to the stress cone 4 by the plurality of springs 83 .

The flange fitting 80 is provided with a plurality of first holes and a plurality of second holes (not shown). The plurality of first holes are arranged at predetermined intervals in the circumferential direction of the flange fitting 80 so as to draw a circle. The plurality of second holes are arranged at predetermined intervals in the circumferential direction so as to draw a circle arranged closer to the outer periphery of the flange fitting 80 than the circle drawn by the plurality of first holes. A guide rod 84 is inserted through each first hole. A spring 83 is arranged on the outer circumference of each guide rod 84 . A shaft fitting 82 is inserted through each second hole. A spring 83, a guide rod 84, a bolt 85, and a shaft fitting 82 are attached to the flange fitting 80 so that their longitudinal directions are parallel to the longitudinal direction of the power cable. A spring 83 , a guide rod 84 and a bolt 85 are arranged so as to pass through the inner peripheral hole of the flange fitting 50 . The position of the flange fitting 80 with respect to the flange fitting 50 is adjusted as follows so that this arrangement is possible. A portion of the flange fitting 80 where the guide rod 84 is arranged, that is, a portion where the first hole is formed is arranged inside the inner peripheral hole of the flange fitting 50 . A portion of the flange fitting 80 where the shaft fitting 82 is arranged, that is, a portion where the second hole is formed, is arranged so as to overlap a portion of the flange fitting 50 on the inner peripheral side.

〈Insulator pipe〉
As shown in FIG. 1, the porcelain pipe 3 is a cylindrical insulating member. The basic structure of the porcelain pipe 3 of this example is similar to the porcelain pipe provided in the conventional structure described above. The basic configuration of the porcelain pipe 3 will be described below.

The porcelain pipe 3 has two ends. Of the two ends, the first end 34 is the end arranged on the tip side of the terminal portion 2 of the power cable. Of the two ends, the second end 35 is the end arranged on the root side of the terminal portion 2 of the power cable. The second end 35 usually includes the portion of the insulator 3 having the largest outer diameter. The portion having the maximum outer diameter is usually a flange portion 320, which will be described later. A first electrode portion 38 is arranged on the first end portion 34 side. A second electrode portion 39 is arranged on the second end portion 35 side. The intermediate portion of the porcelain tube 3 has an inner peripheral surface in contact with the outer peripheral surface of the insulating cylindrical portion 41 of the stress cone 4 . The first metal fitting 5 and the second metal fitting 6 are attached to the second end portion 35 of the porcelain pipe 3 .

In particular, the porcelain pipe 3 of Embodiment 1 has a specific shape of the second end portion 35 . The second end portion 35 of the insulator pipe 3 has a portion extending to the outer peripheral side of the insulator pipe 3 from the outer peripheral surface of the portion of the insulator pipe 3 on the first end portion 34 side. The second end 35 of the insulator 3 is provided with a flange portion 320 . The insulator pipe 3 is directed toward the second end portion 35 side from the flange portion 320 so that the end surface of the insulator pipe 3 facing the second end portion 35 side is composed of a plurality of surfaces instead of one plane. It has an extended portion. Therefore, the porcelain pipe 3 has a plurality of end faces arranged to face the second end 35 side.

The plurality of end surfaces comprise a first surface 31 , a second surface 32 and a third surface 33 . The first surface 31 and the second surface 32 are arranged with a gap in the radial direction of the porcelain pipe 3 . The second surface 32 is arranged outside the first surface 31 in the radial direction. A third surface 33 is arranged between the first surface 31 and the second surface 32 . However, the first surface 31 , the second surface 32 and the third surface 33 are shifted in the longitudinal direction of the insulator 3 . The first surface 31 and the second surface 32 are arranged closer to the first end 34 than the third surface 33 is. In other words, the third surface 33 is arranged closer to the second end 35 than the first surface 31 and the second surface 32 are. The third surface 33 is arranged toward the side opposite to the first end 34 with respect to the first surface 31 and the second surface 32 . The porcelain pipe 3 having three end faces having such an arrangement relationship has a tubular portion 330 extending toward the second end portion 35 side from the first face 31 and the second face 32 . The first surface 31 and the second surface 32 form end surfaces of the flange portion 320 that are arranged to face the second end portion 35 side. The third surface 33 constitutes an end surface of the tubular portion 330 .

When the second end portion 35 of the insulator 3 is viewed in plan in the longitudinal direction of the insulator 3 , the first surface 31 , the third surface 33 , and the second surface 32 are arranged in order from the inside of the insulator 3 in the radial direction. When the porcelain tube 3 and the terminal portion 2 of the power cable are viewed in plan in the longitudinal direction, the first surface 31, the third surface 33, and the second surface 32 are arranged in order from the side closer to the terminal portion 2 of the power cable. . When the porcelain pipe 3 and the terminal portion 2 of the power cable are viewed in plan in the radial direction of the porcelain pipe 3, the tubular portion 330 and the third surface are closer to the root side of the terminal portion 2 of the power cable than the first surface 31 and the second surface 32. 33 are arranged.

In this example, the first surface 31 , the second surface 32 and the third surface 33 are all planes parallel to the radial direction of the insulator 3 . Also, the first surface 31, the second surface 32, and the third surface 33 are all annular surfaces. When the porcelain pipe 3 is viewed from above in the longitudinal direction of the porcelain pipe 3, the first surface 31, the third surface 33, and the second surface 32 are arranged concentrically. The tube portion 330 is cylindrical. That is, the inner peripheral surface of the tubular portion 330 connecting the first surface 31 and the third surface 33 is a cylindrical surface. The outer peripheral surface of the cylindrical portion 330 connecting the second surface 32 and the third surface 33 is also a cylindrical surface. The shape of the second end portion 35 of the porcelain pipe 3 is a simple shape.

In this example, the first surface 31 and the second surface 32 are arranged at the same position in the insulator tube 3 in the longitudinal direction. That is, the first surface 31 and the second surface 32 are arranged on the same imaginary plane. In this case, as shown in FIG. 2, the projection length L1 of the tubular portion 330 from the _first surface 31 and the projection length L2 of the tubular portion 330 from the _second surface 32 are equal. Also from this point, the shape of the second end portion 35 of the porcelain pipe 3 is a simple shape. In addition, the length along the surface of the cylindrical portion 330 from the first surface 31 to the second surface 32 can be easily obtained because the projection length L1 and the projection length L2 _{are equal} . The above length is the sum of twice the projecting length L ₁ and the length L ₃ along the radial direction of the porcelain pipe 3 on the third surface 33 .

The protrusion lengths L ₁ and L ₂ can be selected as appropriate. The length along the surface of the tubular portion 330 from the first surface 31 to the second surface 32 increases as the projection lengths L ₁ and L ₂ increase. As a result, the insulation distance between the first metal fitting 5 arranged on the first surface 31 and the second metal fitting 6 arranged on the second surface 32 is increased.

The sizes of the first surface 31, the second surface 32, and the third surface 33 can be selected as appropriate. The size of the first surface 31 should be selected according to the width of the flange fitting 50, which will be described later. The size of the second surface 32 may be selected according to the width of the flange fitting 60, which will be described later. In this example, the first surface 31 is approximately equal to the width of the flange fitting 50 .

Since the first surface 31 has a predetermined size, the inner peripheral surface 332 of the cylindrical portion 330 of the insulator 3 is arranged radially outside of the insulator 3 than the following inner peripheral surface 352 of the insulator 3 . The inner peripheral surface 352 is the inner peripheral surface of the portion of the porcelain insulator 3 that is located closer to the first end 34 than the first surface 31 and is the portion near the first surface 31 . A space corresponding to the size of the first surface 31 along the radial direction is provided inside the cylindrical portion 330 . The inner space of the cylindrical portion 330 can be used as a space for accommodating the root side portion of the pressing metal fitting 8 described above and the tip portion of the first metal fitting 5 described later. In this example, the root side portion of the pressing metal fitting 8 is arranged inside the cylindrical portion 330 . The root side portion of the pressing metal fitting 8 includes the root side ends of the spring 83, the guide rod 84, and the bolt 85, the flange metal fitting 80, and the shaft metal fitting .

In addition, it is preferable that corners connecting a plurality of surfaces at the second end 35 of the porcelain pipe 3 are curved surfaces. The corners are, as shown in FIG. is the corner of Since the corners are curved, cracks are less likely to occur in the porcelain pipe 3 during manufacturing.

The first electrode portion 38 is a cylindrical member with a bottom. The outer peripheral surface of the first electrode portion 38 is in contact with the inner peripheral surface of the first end portion 34 . The first electrode portion 38 has a recess into which a compression sleeve 200 is fitted. By fitting the compression sleeve 200 into the recess, the first electrode portion 38 is electrically connected to the end portion of the conductor 20 described above.

The second electrode portion 39 is embedded inside the second end portion 35 . The above-described flange fitting 50 is attached to the second electrode portion 39 with metal bolts indicated by dashed lines in FIG. The shielding layer 23 and the second electrode portion 39 are electrically connected by the bolt and the flange fitting 50 .

An electric insulating material can be used for the material of the insulating tube 3 . The constituent material is, for example, a resin composition such as an epoxy resin.

The porcelain pipe 3 can be manufactured by a known resin composition molding method. For example, the porcelain pipe 3 is molded in a mold such that the second end 35 is arranged upward and the first end 34 is arranged downward. In this molding method, the porcelain pipe 3 having a long cylindrical portion 330 can be easily molded. If the length of the tubular portion 330 is long, the projection lengths L ₁ and L ₂ of the tubular portion 330 can be adjusted by cutting the tubular portion 330 . As a result, the insulation distance between the first metal fitting 5 and the second metal fitting 6 can be easily adjusted. In this case, the third surface 33 is the cutting surface.

The porcelain pipe 3 of this example is a molded body in which the insulating portion, the first electrode portion 38 and the second electrode portion 39 made of the resin composition described above are integrated. Such a molded body can be produced, for example, by filling a mold in which the first electrode portion 38 and the second electrode portion 39 are arranged at predetermined positions of the mold with a resin composition in a fluid state. .

<First metal fitting>
The first metal fitting 5 is used to protect the root side portion of the terminal portion 2 of the power cable and to ground the aforementioned shielding layer 23 . In this example, the second electrode portion 39 described above is also grounded by being electrically connected to the first metal fitting 5 .

The first metal fitting 5 of this example includes a flange metal fitting 50, a body portion 51, and a bolt 52, as shown in FIG. The body portion 51 is a cylindrical member. The body portion 51 is arranged so as to cover the portion on the root side of the terminal portion 2 of the power cable. The flange fitting 50 is an annular plate-shaped member. The flange fitting 50 is arranged so as to be in contact with the first surface 31 of the porcelain pipe 3 and is attached to the end portion 390 of the second electrode portion 39 with the bolts described above. The body portion 51 is fixed to the insulator pipe 3 by being fixed to the flange metal fitting 50 with the bolt 52 .

The body portion 51 of this example has a first portion having a first inner diameter and a second portion having a second inner diameter. The first inner diameter is larger than the second inner diameter and smaller than the inner diameter of the tubular portion 330 of the insulator 3 . Therefore, the first portion can be arranged inside the tubular portion 330 .

The first portion of the main body portion 51 is the portion on the distal end side of the main body portion 51 . The first portion covers the intermediate portion between the edge of the outer semi-conducting layer 22 and the edge of the shielding layer 23 described above. Also, the first portion covers the portion on the root side of the pressing fitting 8 that is arranged radially outside the terminal portion 2 of the power cable. A flange portion extending radially outward of the main body portion 51 from the outer peripheral surface of the main body portion 51 is provided at the distal end portion of the main body portion 51 . By attaching the bolts 52 to the flange portion, the tip portion of the main body portion 51 is attached to the first surface 31 of the insulator pipe 3 via the flange fitting 50 .

The second portion of the main body portion 51 is the portion on the root side of the main body portion 51 . The second part mainly covers the ends of the shielding layer 23 mentioned above. Also, the second portion is electrically connected to the shielding layer 23 . A waterproof layer 500 is provided on the outer periphery of the second portion.

The width of the flange fitting 50 is the size along the radial direction of the flange fitting 50 and is the difference between the outer diameter and the inner diameter of the flange fitting 50 . In this example, the width of the flange fitting 50 is approximately equal to the size of the first surface 31 of the insulator 3 along the radial direction of the insulator 3 . Specifically, the inner diameter of the flange fitting 50 is substantially equal to the inner diameter of the circle drawn by the inner peripheral surface 352 of the insulator 3 . The outer diameter of the flange fitting 50 is slightly smaller than the inner diameter of the tubular portion 330 of the insulator 3 . Therefore, the end surface of the flange fitting 50 on the tip side can reliably contact the first surface 31 .

In addition, a sealing material is arranged between the first surface 31 and the flange fitting 50 and between the flange fitting 50 and the flange portion of the main body portion 51 . The internal space of the porcelain pipe 3 and the internal space of the first metal fitting 5 are kept liquid-tight and air-tight by the sealing material.

A known metal material can be used for the first metal fitting 5 and the second metal fitting 6, which will be described later. A constituent material of the body portion 51 is, for example, copper, a copper alloy, aluminum, an aluminum alloy, or the like. A constituent material of the flange fittings 50 and 60 is, for example, a copper alloy. A constituent material of the bolts 52 and 62 is, for example, stainless steel.

<Second bracket>
The second metal fitting 6 is used to fix the porcelain pipe 3 to the GIS case 9 as described above. The second metal fitting 6 of this example includes a flange metal fitting 60 as shown in FIG. The flange fitting 60 is an annular plate-shaped member. The flange fitting 60 is arranged so as to be in contact with the second surface 32 of the porcelain pipe 3 and fixed to the GIS case 9 with bolts 62 .

The width of the flange fitting 60 is the size along the radial direction of the flange fitting 60 and is the difference between the outer diameter and the inner diameter of the flange fitting 60 . In this example, the width of the flange fitting 60 is larger than the size of the second surface 32 of the insulator 3 along the radial direction of the insulator 3 . Therefore, the end surface of the flange fitting 60 on the tip end side can reliably contact the second surface 32 .

(Construction procedure)
The power cable termination structure 1 of Embodiment 1 can be constructed in the same manner as a known procedure. Therefore, detailed description is omitted.

(Effect)
In the power cable termination structure 1 of Embodiment 1, the porcelain tube 3 has a specific third surface 33 . Therefore, the insulation distance between the first metal fitting 5 and the second metal fitting 6 is the length along the surface of the tubular portion 330 of the insulator 3 . Specifically, the insulation distance is the _total value of the protrusion length L1, the protrusion length _{L2 ,} and the length L3. In contrast, the insulation distance of the conventional structure described above corresponds _only to the protrusion length L2. Therefore, the insulation distance in the power cable termination structure 1 of Embodiment 1 is longer than the insulation distance in the conventional structure. As a result, the insulation distance between the shield layer 23 electrically connected to the first metal fitting 5 and the second metal fitting 6 is longer than the insulation distance of the conventional structure. In this respect, the power cable termination structure 1 including the insulator 3 of Embodiment 1 is superior in insulation strength to the conventional structure. By providing the specific third surface 33 to the porcelain insulator 3 of Embodiment 1, it is possible to construct the power cable terminating structure 1 that is superior in insulation strength to that of the conventional structure as described above.

Furthermore, the power cable termination structure 1 of the first embodiment and the porcelain tube 3 of the first embodiment have the following effects.
(1) The shape of the porcelain pipe 3 is simple. Therefore, the porcelain pipe 3 is also excellent in manufacturability.
(2) The cylindrical portion 330 of the porcelain pipe 3 is cylindrical and the third surface 33 is flat. Therefore, the length of the cylindrical portion 330 of the porcelain insulator 3 can be easily adjusted by designing the length of the cylindrical portion 330 of the porcelain insulator 3 to be relatively long at the manufacturing stage. As a result, the insulation distance between the first metal fitting 5 and the second metal fitting 6 can be easily adjusted.
(3) The portion on the tip side of the first metal fitting 5 is arranged inside the cylindrical portion 330 of the porcelain pipe 3 . Therefore, the cylindrical portion 330 mechanically protects the first metal fitting 5 and protects it from the external environment.
(4) The size of the first surface 31 and the second surface 32 of the insulator 3 along the radial direction of the insulator 3 is not too large. In this respect, the porcelain tube 3 and the power cable termination structure 1 tend to be small.

(5) By arranging the first surface 31 and the second surface 32 at the same position in the longitudinal direction of the insulator 3, the following effects can be obtained.
(5-1) The tubular portion 330 of the porcelain insulator 3 can ensure a long insulation distance between the first metal fitting 5 and the second metal fitting 6 as described above.
(5-2) The following effects (a) to (c) are obtained compared to the case where the first surface 31 and the second surface 32 are displaced in the longitudinal direction.
(a) It is easy to adjust the length of the tubular portion 330 .
(b) The portion of the first metal fitting 5 that is located inside, that is, the portion that is protected by the cylindrical portion 330 tends to become large.
(c) A wide internal space of the cylindrical portion 330 is ensured. Therefore, the length of the pressing metal fitting 8 can be shortened. As a result, the length along the longitudinal direction of the power cable termination structure 1 can be made shorter than the length of the conventional structure described above. In this respect, the power cable termination structure 1 is compact. Moreover, since the length of the pressing metal fitting 8 is short, the manufacturing cost of the pressing metal fitting 8 is also reduced.

The above effect (c) will be described in detail. Since the internal space is wide, the portion of the pressing fitting 8 that is arranged on the root side of the terminal portion 2 of the power cable can be arranged inside the cylindrical portion 330 . In this case, the length of the pressing metal fitting 8 can be made shorter than the length of the pressing metal fitting provided in the above-described conventional structure. In this example, the length of the shaft fitting 82, the length of the spring 83, the length of the guide rod 84, and the length of the bolt 85 can be shortened. Since the stud bolt 820 is used in this example, the length of the shaft fitting 82 can be further shortened. On the other hand, in the pressing metal fitting provided in the above-described conventional structure, the shaft metal fitting and the like are arranged closer to the root side of the power cable than the above-described insulating porcelain tube. Therefore, the length of the shaft fitting and the like in the above-described conventional structure tends to be longer than the length of the shaft fitting 82 and the like.

[Modification]
At least one of the following modifications can be made to the power cable termination structure 1 of the first embodiment and the porcelain insulator 3 of the first embodiment.
(Modification 1)
(1) The cylindrical portion 330 of the porcelain pipe 3 has a shape other than a cylindrical shape.
For example, at least one of the inner peripheral surface and the outer peripheral surface of the tubular portion is not a cylindrical surface. As a specific example, the outer shape of the cylindrical portion is frustum-shaped, and the cross-sectional shape of the cylindrical portion is not rectangular but trapezoidal.
(2) The third surface 33 of the porcelain pipe 3 is an inclined surface. Specifically, the third surface 33 is not a plane parallel to the radial direction of the porcelain pipe 3 but a plane provided so as to intersect the radial direction. Alternatively, the third surface 33 is a curved surface.
In Modification 1, the insulation distance between the first metal fitting 5 and the second metal fitting 6 is longer than the insulation distance in the first embodiment. Therefore, Modification 1 is superior to Embodiment 1 in insulation strength. In forming the insulator pipe of Modification 1, in (1), for example, a plurality of split molds that can divide the insulator pipe in the radial direction are used. In (2), for example, a mold for molding the third surface is used.

(Modification 2)
The first surface 31 and the second surface 32 of the insulator 3 are arranged to be shifted in the longitudinal direction of the insulator 3 . Further, the root side portion of the pressing metal fitting 8 is not arranged inside the cylindrical portion 330 of the insulator 3 , but is arranged closer to the root than the third surface 33 of the insulator 3 . For example, the first surface 31 or the second surface 32 is arranged below the position shown in FIG. As a specific example, the first surface 31 is arranged between the second surface 32 and the third surface 33 . In this arrangement state, the root side portion of the pressing metal fitting 8 is arranged closer to the root side than the third surface 33 .
In Modification 2, although the shaft fitting is longer, the size of the insulator tube 3 along the radial direction tends to be smaller than in the first embodiment.

[Test example]
The insulation performance was evaluated by the following three tests for the termination structure of the electric power cable provided with the porcelain tube.
Sample no. One power cable termination structure includes the porcelain tube 3 of Embodiment 1 described above.
In the DC withstand voltage test, a DC voltage of 25 kV was applied to the shield layer of the power cable for 1 minute to evaluate whether or not the cylindrical portion 330 of the porcelain insulator 3 would be abnormal.
In the lightning impulse withstand voltage test, a positive impulse voltage was applied to the power cable 10 times, and then a negative impulse voltage was applied 10 times to evaluate whether or not an abnormality would occur in the cylindrical portion 330 . The applied voltage is ±72.5 kV.
In the lightning impulse breakdown test, an impulse voltage was applied to the power cable and the impulse voltage was measured when flashover occurred on the surface of the shielding layer.

As a result, for the DC withstand voltage test and the lightning impulse withstand voltage test, sample No. No abnormalities occurred in 1, and good results were obtained. For the lightning impulse destructive test, sample No. The impulse voltage of 1 has a magnitude that poses no problem in practice, and good results were obtained. For these reasons, sample no. 1 was shown to be excellent in insulating strength.

1 power cable termination structure 2 power cable terminal 3 porcelain tube 4 stress cone 5 first metal fitting 6 second metal fitting 8 pressing metal fitting 9 GIS case 20 conductor 21 insulating layer 22 external semiconductive layer 23 shielding Layer 24 Sheath 31 First surface 32 Second surface 33 Third surface 34 First end 35 Second end 38 First electrode portion 39 Second electrode portion 41 Insulating tubular portion 42 Semiconductive portion 50 Flange metal fitting 51 Body part 52 Bolt 60 Flange metal fitting 62 Bolt 80 Flange metal fitting 81 Ring part 82 Shaft metal fitting 83 Spring 84 Guide rod 85 Bolt 200 Compression sleeve 320 Flange part 330 Cylindrical part 332 Inner peripheral surface 352 inner peripheral surface, 390 end 500 waterproof layer 820 stud bolt _{L1 , L2} protruding length, L3 length

Claims (5)

a terminal portion of a power cable having a conductor, an insulating layer, an outer semiconductive layer, and a shielding layer in order from the inside;
a porcelain tube that covers a distal end portion of the terminal portion of the power cable;
a first metal fitting that covers a root side portion of the terminal portion of the power cable;
The porcelain pipe has a plurality of end faces arranged to face the root side,
The plurality of end faces are
a first surface to which the tip of the first metal fitting is attached;
a second surface on which a second metal fitting for fixing the porcelain pipe to a predetermined object is attached;
a third surface arranged between the first surface and the second surface such that the first metal fitting and the second metal fitting are spaced apart in the radial direction of the insulator pipe;
The third surface is arranged closer to the base than the first surface and the second surface,
Power cable termination structure. The porcelain pipe has a cylindrical tubular portion extending toward the root side from the first surface and the second surface,
The power cable termination structure according to claim 1, wherein the third surface is an end surface of the cylindrical portion. 3. The power cable termination structure according to claim 2, wherein said first surface and said second surface are arranged at the same position in the longitudinal direction of said insulator. a stress cone covering the edge of the insulating layer exposed from the outer semi-conductive layer;
a pressing fitting for pressing the stress cone from the root side toward the tip side;
The first metal fitting is electrically connected to the shielding layer,
4 . The power cable termination structure according to claim 3 , wherein the portion of the pressing fitting disposed on the root side is disposed inside the cylindrical portion. A porcelain tube used for a termination structure of a power cable,
a first end portion disposed on the tip side of the terminal portion of the power cable;
a second end portion arranged on the root side of the terminal portion of the power cable;
A plurality of end faces arranged to face the second end side,
The plurality of end faces are
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a second surface arranged radially outside the insulator pipe relative to the first surface;
a third surface disposed between the first surface and the second surface;
The third surface is arranged closer to the second end than the first surface and the second surface,
porcelain pipe.

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