JP2024018329A - Bushings and cable terminations - Google Patents

Abstract

[Problem] To provide a highly reliable bushing that can prevent damage to the insulating tube of the bushing when assembling or disassembling a cable termination. [Solution] The bushing is a bushing for a direct-connection-type termination for connecting a power cable to power equipment, and includes an inner conductor, an insulating tube arranged on the outer periphery of the inner conductor, and an intermediate connection member whose front end is fixed to the open end of the insulating tube by bolt fastening and whose rear end is capable of mounting a fixing member of the cable terminal portion to which spring stress is applied, the intermediate connection member being made of a material stronger than the insulating tube. [Selected Figure] Figure 2

Description

The present invention relates to a bushing and a cable termination connection, and particularly to a technique suitable for use in a device-direct connection type termination connection.

Conventionally, cable termination connections such as a gas termination connection, an oil termination connection, and an air termination connection are known (for example, see Patent Document 1). Generally, a cable terminal connection is a cable terminal part in which a connection material is attached to a main body material (hereinafter referred to as a "bushing") having an inner conductor and a hard insulating tube arranged around the outer periphery of the inner conductor. It is formed by connecting. In particular, the terminal connection part of the device direct connection type used for connection with power equipment such as switchgear has a T-shaped (or L-shaped) bushing that has a device connection part, a power supply part, and a cable connection part. We are prepared.

In a T-shaped bushing for a device-directly connected terminal connection, the ends of the power supply part and the cable connection part have a structure that allows attachment of fixing fittings or rubber insulation plugs for fixing the cable terminal part. There is. For example, at the end of the cable connection part in the bushing disclosed in Patent Document 1, the embedded metal fitting embedded in the insulating tube (3) made of epoxy resin has a fixing metal fitting (stress A pusher flange 62), which is a part of the pushing device 6 that pushes the cone in the axial direction, is directly fixed by bolting.

Patent No. 4283659

As mentioned above, in conventional bushings, the fixing fitting (the cover for the rubber insulating plug when installing a rubber insulating plug), which is subject to the stress of the spring, is directly bolted to the embedded fitting embedded in the bushing. It has a structure that allows Therefore, if the bolts are unbalanced when attaching or removing the cable end and rubber insulating plug to or from the bushing, local stress may concentrate on the insulating tube and cause cracks. be.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a highly reliable bushing and cable termination that prevents the insulating tube of the bushing from being damaged during assembly or disassembly of the cable termination.

The bushing according to the present invention includes:
A bushing for a device direct connection type terminal connection part for connecting a power cable to a power device,
an inner conductor;
an insulating cylinder arranged around the outer periphery of the internal conductor;
an intermediate connecting member whose front end side is fixed to the open end of the insulating cylinder by bolting, and whose rear end side is capable of attaching a fixing member to which spring stress is applied among the cable terminal parts;
The intermediate connecting member is made of a material stronger than the insulating tube.

The cable termination connection part according to the present invention includes:
The above bushing and
the cable terminal portion attached to the bushing,
The cable terminal section includes at least a conductor connection terminal, a stress cone, a compression device, and a protective fitting at the tip end of the power cable,
The compression device includes a pusher, a pusher flange, the spring, and a washer;
The fixing member includes the pusher flange.

According to the present invention, it is possible to prevent the insulating tube of the bushing from being damaged when assembling or disassembling the cable end connection portion.

FIG. 1 is a sectional view showing the internal structure of a cable end connection section to which a bushing according to an embodiment is applied. FIG. 2 is an exploded view of a cable terminal connection section to which the bushing according to the embodiment is applied.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing the internal structure of a cable terminal connection section 1 to which a bushing 10 according to an embodiment is applied. FIG. 2 is an exploded view of the cable end connection section 1 to which the bushing 10 is applied. The cable terminal connection section 1 is, for example, a device-direct connection type terminal connection section for power equipment that requires airtightness, such as a switchgear or a transformer. In the following description, in the first bushing part 10A, the left side in the drawings is referred to as the "tip side" and the right side in the drawings is referred to as the "rear end side", and in the second bushing part 10B, the upper part in the drawings is referred to as the "tip side". , the lower side is referred to as the "rear end side". That is, the side in the direction in which the member is attached is referred to as the "front end side", and the opposite side is referred to as the "rear end side". Further, the end surface on the leading end side is sometimes referred to as the "front end surface", and the end surface on the rear end side is sometimes referred to as the "rear end surface".

As shown in FIG. 1, the cable terminal connection section 1 is configured by attaching a cable terminal section 20 to a bushing 10.

The bushing 10 includes a first bushing portion 10A extending in a first direction (horizontal direction (left-right direction in FIG. 1)) and a second bushing portion 10A extending in a second direction (vertical direction (vertical direction in FIG. 1)) perpendicular to the first direction. It has an extending second bushing portion 10B. The bushing 10 is a so-called T-shaped bushing in which a second bushing part 10B is branched and connected to the axial center of the first bushing part 10A. Note that the bushing 10 may be a so-called L-shaped bushing in which a second bushing portion 10B is connected to an axial end portion of the first bushing portion 10A. In this case, the internal conductor 11, which will be described later, is L-shaped, and the structure is such that there is no energizing section 102, the first receiving port 121, and the rubber insulating plug 40 attached to the receiving port, which will be described later.

The first bushing part 10A has a device connection part 101 to which a power device is connected at one end (the left side in FIG. 1), and a device connection part 101 to which a power device is connected at the other end (the right side in FIG. 1). It has a power charging section 102 to which a power cable is connected. The second bushing portion 10B has a cable connection portion 103 at an open end portion to which the cable terminal portion 20 is connected. Note that the energizing section 102 is closed with a rubber insulating plug 40 during normal use.

The bushing 10 includes an internal conductor 11 , an insulating tube 12 , a shielding layer 13 , a device side fixing flange 14 , a power supply side fixing flange 15 , and an intermediate connection member 16 .

The inner conductor 11 and the insulating tube 12 are integrally formed by, for example, molding. The shielding layer 13 is formed of a conductive paint applied to the outer peripheral surface of the insulating cylinder 12. The device side fixing flange 14 is disposed on the end surface of the device connection portion 101 side (the left side in FIG. 1) of the first bushing 10A excluding the device connection portion 101, and is located at the rear end of the device connection portion 101. placed on the outer periphery. The power supply side fixing flange 15 is arranged at the end of the insulating tube 12 in the power supply section 102 .

The intermediate connection member 16 is arranged at the end of the insulating tube 12 in the cable connection section 103. A push metal flange 232 (fixing member) of the cable terminal portion 20 can be attached to the rear end side of the intermediate connecting member 16. The intermediate connection member 16 is made of a material stronger than the insulating cylinder 12. A metal material is suitable for the material of the intermediate connection member 16. As the material of the intermediate connection member 16, for example, a conductive material such as brass, stainless steel alloy, or aluminum alloy can be used.

The intermediate connecting portion 16 is, for example, a plate-like member having an annular shape in a plan view, and has a through hole formed in the center through which the distal end side of the compression device 23 of the cable terminal portion 20 is inserted. The inner diameter of the intermediate connecting member 16 is larger than the outer diameter of the compression device 23 on the distal end side. Further, the outer diameter of the intermediate connecting member 16 is smaller than the outer diameter of the stepped portion 123, which will be described later. Note that the edges of the front end surface and rear end surface of the intermediate connecting member 16 may be chamfered. On the rear end surface of the intermediate connection member 16, a plurality of non-penetrating screw holes (female screw portions) for attaching the fixing member of the power cable 50 are formed along the circumferential direction. In addition, a plurality of bolt insertion holes are formed in the intermediate connection member 16 along the circumferential direction for bolting to the open end of the insulating cylinder 12.

The intermediate connecting member 16 is fitted into the open end of the insulating tube 12 . Specifically, a stepped portion 123 is formed at the open end of the insulating cylinder 12 and is recessed from the rear end side toward the leading end. It is mechanically fixed to the tube 12. A surface 14 on the distal end side of the stepped portion 123 (hereinafter referred to as “attachment surface 14”) is orthogonal to the axis of the cable terminal portion 20. A plurality of embedded metal fittings each having a female screw portion for bolting the intermediate connecting member 16 are embedded in the mounting surface 124 . The intermediate connecting member 16 is fixed to the mounting surface 124 by inserting a bolt into the bolt insertion hole of the intermediate connecting member 16 and fastening the bolt to the embedded fitting.

The shielding layer 13 functions as a shielding part that prevents electrical leakage to the outside and as an electric field relaxation part that relieves the electric field within the bushing 10. The shielding layer 13 is formed on the entire outer circumferential surface of the insulating cylinder 12 from the device side fixed flange 14 to the power supply side fixed flange 15 in the first bushing portion 10A. Further, the shielding layer 13 is formed in the second bushing portion 10B at a portion of the outer peripheral surface of the insulating tube 12 excluding the end portion on the cable connection portion 103 side. The part of the second bushing part 10B where the shielding layer 13 is not formed (the part between the end of the shielding layer 13 and the pusher flange 232 in FIG. 1) is a grounding structure on the equipment side and a grounding structure on the power cable 50. This becomes the edge cutting portion 17 that insulates the edges.

The shielding layer 13 is electrically connected to the device side fixed flange 14 and the power supply side fixed flange 15. The shielding layer 13 is electrically connected to the equipment case 60 of the power equipment via the equipment side fixing flange 14 and grounded. That is, the end 131 of the shielding layer 13 in the device connection section 101 is a grounded end, and the end of the shielding layer 13 in the power supply section 102 and the cable connection section 103 is a non-grounded end. The resistance of the shielding layer 13 in the conduction path connecting the grounded end (end 131) of the device connection section 101 and the non-grounded end (end 132) of the power charging section 102 is, for example, 10Ω or less.

The internal conductor 11 is formed of a conductive material suitable for conducting electricity, such as copper, aluminum, copper alloy, or aluminum alloy. The internal conductor 11 has a first conductor connection part 111 that connects to a power charging cable conductor (not shown) inserted into the power supply part 102 and a cable conductor 51 of the power cable 50 inserted into the cable connection part 103. It has a second conductor connection portion 112 for connection. Note that FIG. 1 shows normal use, and the rubber insulating plug 40 is attached to the power supply section 102, and the conductor on the tip side of the rubber insulating plug 40 is attached to the first conductor connection section 111 of the internal conductor 11. are electrically connected.

The insulating cylinder 12 is made of a hard plastic resin material with high mechanical strength (for example, epoxy resin, fiber reinforced plastics (FRP), etc.). The insulating tube 12 has a first receiving port 121 for receiving a charging cable (not shown) at the end on the power charging section 102 side, and receives the cable terminal section 20 at the end on the cable connecting section 103 side. It has a second receiving port 122 . The first receiving port 121 communicates with the first conductor connecting portion 111 of the internal conductor 11 , and the second receiving port 122 communicates with the second conductive connecting portion 112 of the internal conductor 11 . A stepped portion 123 is formed on the inner peripheral surface of the second receiving port 122 on the rear end side. The stepped portion 123 is formed, for example, so that the rear end surface of the insulating cylinder 12 and the rear end surface of the intermediate connection member 16 are flush with each other. Here, "flush" means that a plurality of different surfaces are in a positional relationship with no difference in level.

The outer diameter of the device-side fixing flange 14 is larger than the diameter of a fixing opening (not shown) provided in the device case 60. The device connecting portion 101 of the bushing 10 is inserted into the fixing opening of the device case 60, and the device side fixing flange 14 is bolted to the device case 60 via a seal member (symbol omitted) such as an O-ring. 10 is hermetically fixed to the equipment case 60.

In the cable terminal connection section 1, the cable terminal section 20 has connection members such as a conductor connection terminal 21, a stress cone 22, a compression device 23, a protective metal fitting 24, and an anticorrosion layer (not shown) at the distal end of the power cable 50. Installed and configured.

The power cable 50 is, for example, a power cable insulated with rubber or plastic, as shown in FIG. The power cable 50 includes, in order from the center, a cable conductor 51, a cable insulator 52, a cable outer semiconducting layer 53, a cable shielding layer 54, a cable sheath (not shown), and the like. At the cable terminal section 20, each layer is exposed by stripping off a predetermined length from the distal end of the power cable 50.

Note that when the power cable 50 is a free stripping type (also called a frist type), the tip of the cable external semiconductive layer 53 is It is preferable to provide an external semiconductive treatment section 25 on the side. The external semiconductive processing portion 25 is formed by applying a conductive paint to the stripped end of the cable external semiconductive layer 53, or by wrapping a semiconductive tape such as polyethylene and molding it.

A conductive connection terminal 21 made of, for example, copper, aluminum, a copper alloy, an aluminum alloy, or the like and suitable for conducting electricity is connected to the cable conductor 51 by compression. Thereby, the cable conductor 51 and the conductor connection terminal 21 are electrically and mechanically connected. A stress cone 22 is attached to the outer periphery extending from the cable insulator 52 to the tip of the external semiconductive processing section 25 . Furthermore, a compression device 23 and a protective fitting 24 are attached to the rear end side of the stress cone 22 .

The stress cone 22 is a pre-molded insulating cylinder having an insulating part (not shown) on the front end side and a semi-conducting part (not shown in the rear end part) integrally formed by molding, and having a spindle shape as a whole. The insulating part is made of an insulating rubber material such as ethylene propylene rubber (EP rubber) or silicone rubber, and the semiconductive part is made of semiconductive rubber material such as semiconductive ethylene propylene rubber (EP rubber) or silicone rubber. Made of conductive rubber material.

The rear end portion (semiconducting portion) of the stress cone 22 is electrically connected to the cable outer semiconducting layer 53 of the power cable 50 . In this embodiment, the rear end portion (semiconducting portion) of the stress cone 22 is connected to the external semiconductive processing portion 25 and is electrically connected to the cable external semiconducting layer 53 via the external semiconducting processing portion 25. It is connected to the. When the cable outer semiconducting layer 53 is a bond type, the end of the cable outer semiconducting layer 53 is formed into a slope shape so that it is directly connected to the rear end (semiconducting portion) of the stress cone 22. Good too. The outer peripheral surface of the tip side (insulating part) of the stress cone 22 has a shape corresponding to the second receiving port 122 of the insulating tube 12 of the bushing 10, and when the stress cone 22 is pressed by the compression device 23, the insulating tube is compressed. 12 second receiving ports 122 .

The compression device 23 includes a pusher 231, a pusher flange 232, a spring 233, a washer 234, and the like. The pusher flange 232 is a fixing member for fixing the cable end portion 20 to the bushing 10. The pusher flange 232 is configured such that the rear end surface of the recess (bottom surface of the recess) and the rear end of the pusher 231 are separated by a predetermined distance so that the recess on the tip side covers the outer periphery of the rear end of the pusher 231. In the fixed and assembled state of the cable end connection 1, the spring 233 is stressed. The spring 233 passes through the pusher flange 232 and is disposed between the pusher 231 and the washer 234 such that its tip is accommodated in a groove provided at the rear end of the pusher 231 .

After stripping the tip of the power cable 50, the protective fitting 24, compression device 23, and stress cone 22 are attached to the power cable 50, and the conductor connection terminal 21 is attached to the cable conductor 51, thereby assembling the cable end portion 20. It will be done. By fixing the push metal flange 232 to the bushing 10 by fastening bolts, the outer peripheral surface of the insulating part on the tip side of the stress cone 22 is pressed against the inner wall surface of the second receiving port 122 of the insulating tube 12, and the conductor connection terminal 21 is electrically connected to the internal conductor 11. By adjusting the position of the washer 234 in the axial direction, the urging force by the spring 233 is adjusted.

In this embodiment, the push metal flange 232 of the cable terminal portion 20 is not attached directly to the insulating tube 12 of the bushing 10, but is attached to the intermediate connection member 16 fixed to the insulating tube 12. . When assembling or disassembling the cable end connection part 1 , even if the bolts are attached or removed unevenly and stress is locally concentrated on the bushing 10 , the intermediate connection member 16 , which is stronger than the insulating tube 12 , receives the stress. Therefore, damage such as cracks will not occur to the bushing 10.

In addition, since the bushing for the device-directly connected terminal connection part has large restrictions on the radial dimension, the outer diameter of the insulating tube 12 is increased to ensure the strength of the part of the insulating tube 12 where the push metal flange 232 is attached. That is difficult. On the other hand, when the bushing 10 of this embodiment is applied, the strength of the mounting portion of the push metal flange 232 can be increased with the same dimensional design as the conventional one.

Further, in the bushing 10, it is necessary to ensure a predetermined length for the edge cut portion 17. On the other hand, when the intermediate connecting member 16 is disposed on the rear end surface of the insulating tube 12, the length of the second bushing portion 10B becomes longer. In this embodiment, the intermediate connecting member 16 is arranged so as to fit inside the open end of the insulating cylinder 12, so that by providing the intermediate connecting member 16, the second bushing portion 10B can be prevented from becoming elongated and the edge can be cut. The length of the portion 17 can be ensured.

As described above, the bushing 10 according to the present embodiment is a bushing for a device-direct connection type terminal connection portion for connecting the power cable 50 to a power device, and includes the internal conductor 11 and the outer periphery of the internal conductor 11. The intermediate connecting member 16 includes an insulating cylinder 12 to be arranged, and an intermediate connecting member 16 that is fixed to the open end of the insulating cylinder 12 and to which a push metal flange 232 (fixing member) of the cable terminal part 20 can be attached. It is made of a material stronger than the insulating cylinder 12. Specifically, the intermediate connection member 16 is made of a metal material.
According to the bushing 10, the insulating cylinder 12 of the bushing 10 can be prevented from being damaged when the cable terminal connection part 1 is assembled or disassembled, and the reliability of the bushing 10 is improved. Further, even if a problem occurs in the cable terminal section 20 and the cable terminal connection section 1 is disassembled, the bushing 10 will not be damaged and can be reused.

Further, in the bushing 10, the intermediate connecting member 16 is fitted inside the open end of the insulating cylinder 12. Thereby, the intermediate connection member 16 can be provided without increasing the size of the bushing 10 (second bushing portion 10B).

Furthermore, in the bushing 10, the insulating tube 12 has a stepped portion 123 into which the intermediate connecting member 16 is fitted. Thereby, the intermediate connecting member 16 can be provided without changing the dimensional design of the insulating tube 12.

Further, in the bushing 10, the intermediate connecting member 16 is a plate-like member having an annular shape in plan view. This disperses the stress that occurs when the bolts are attached or removed unevenly, so that even large stresses can be withstood, and the reliability of the bushing 10 is further improved.

Further, in the bushing 10, the intermediate connecting member 16 is fixed to an embedded metal fitting embedded in the insulating cylinder 12 by fastening bolts. Thereby, when the cable end portion 20 extends in the vertical direction as in the embodiment, it is possible to prevent the intermediate connection member 16 from falling off from the insulating tube 12 due to the weight of the cable end portion 20.

The bushing 10 also includes a first bushing part 10A extending in a first direction and a second bushing part 10B extending in a second direction perpendicular to the first direction. , has a device connection section 101 provided at one end to which a power device is connected, and a power charging section 102 provided at the other open end to which a power charging cable is connected during a voltage withstand test. However, the second bushing part 10B has a cable connection part 103 to which the cable terminal part 20 is connected at the open end, and the first bushing part 10A and the second bushing part 10B are T-shaped. It is connected. This makes it possible to increase the strength of the mounting portion of the push metal flange 232 with the same dimensional design as the conventional bushing for a device-directly connected terminal connection portion that has large radial dimension restrictions.

As above, the invention made by the present inventor has been specifically explained based on the embodiments, but the present invention is not limited to the above embodiments, and can be modified without departing from the gist thereof.

For example, in the embodiment, a configuration has been described in which the intermediate connection member 16 is provided on the cable connection section 103 side, but it may be provided on the power charging section 102 side. Further, in this case, a stepped portion may be provided at the open end of the insulating tube 12 on the side of the voltage application section 102, which is recessed from the rear end side toward the front end side.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Cable end connection part 10 Bushing 10A First bushing part 10B Second bushing part 11 Internal conductor 12 Insulating cylinder 13 Shielding layer 14 Equipment side fixing flange 15 Power supply side fixing flange 16 Intermediate connection member 17 Edge cutting part 20 Cable terminal part 232 Push Metal fitting flange 50 Power cable

Claims (7)

A bushing for a device direct connection type terminal connection part for connecting a power cable to a power device,
an inner conductor;
an insulating cylinder arranged around the outer periphery of the internal conductor;
an intermediate connecting member whose front end side is fixed to the open end of the insulating cylinder by bolting, and whose rear end side is capable of attaching a fixing member to which spring stress is applied among the cable terminal parts;
The intermediate connecting member is made of a material having higher strength than the insulating tube.
Bushing. The intermediate connecting member is a plate-like member having an annular shape in a plan view, and has a through hole through which the front end side of the compression device forming the cable terminal portion is inserted, and the fixing member is attachable to the rear end side. the member forming part of the compression device;
Bushing according to claim 1. The intermediate connecting member is made of a metal material.
Bushing according to claim 1. The intermediate connecting member is fitted into the open end of the insulating cylinder.
Bushing according to claim 1 or 2. The insulating tube has a stepped portion into which the intermediate connecting member is fitted.
Bushing according to claim 4. a first bushing portion extending in a first direction;
a second bushing portion extending in a second direction perpendicular to the first direction,
The first bushing part includes a device connection part provided at one end to which a power device is connected, and a power charging part provided at the other open end to which a power charging cable is connected during a voltage resistance test. and,
The second bushing part has a cable connection part at an open end part to which a cable terminal part is connected,
The first bushing part and the second bushing part are connected to form a T-shape.
Bushing according to claim 3. The bushing according to claim 2;
the cable terminal portion attached to the bushing,
The cable terminal section includes at least a conductor connection terminal, a stress cone, a compression device, and a protective fitting at the tip end of the power cable,
The compression device includes a pusher, a pusher flange, the spring, and a washer;
The fixing member is constituted by the push metal flange.
Cable termination connection.

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