JP7545127B2 - Power cable termination structure - Google Patents

Description

The present disclosure relates to a termination structure for a power cable.
This application claims priority based on Japanese Patent Application No. 2021-085668 dated May 20, 2021, and incorporates all of the contents of the above-mentioned Japanese application by reference.

The power cable connection portion of Patent Document 1 comprises a power cable, a connection terminal, a pre-molded insulator, and an electrode.

The power cable comprises a cable conductor and a cable insulation. The cable insulation covers the outer circumference of the cable conductor. The end of the power cable is step-stripped. The step-stripping exposes the end of the cable conductor and the end of the cable insulation.

The connection terminal is a tubular member having a blind hole. The end of the cable conductor is disposed inside this blind hole. The connection terminal has an axial portion and a tubular portion, which are arranged in that order from the tip to the rear end of the end of the cable conductor. The axial portion electrically connects the end of the cable conductor to the electrode without being compressed. The tubular portion forms the blind hole. The tubular portion is mechanically connected to the end of the cable conductor by being compressed.

The pre-molded insulation is placed around the end of the cable insulation to form a stress cone. The pre-molded insulation is pressed in the axial direction of the cable by a compression device. This pressure causes the pre-molded insulation to abut against a stopper. The stopper is located between the electrode and the pre-molded insulation. The electrode is placed around the outer periphery of the connection terminal. The pre-molded insulation is compressed by the compression device and the stopper.

JP 2018-33204 A

The power cable termination structure according to the present disclosure comprises:
a power cable having an end of a conductor exposed from an insulating layer;
a sleeve provided around the outer periphery of the end of the conductor;
A stress cone provided on the outer periphery of the insulating layer;
an electrode provided on an outer periphery of the sleeve;
the sleeve has a first connection portion and a second connection portion in this order in a direction from the front end to the rear end of the end of the conductor,
the first connection portion is mechanically connected to the end of the conductor by being compressed;
The second connection portion electrically connects the conductor and the electrode without being compressed.

FIG. 1 is a partial cross-sectional view showing an outline of a termination connection structure for a power cable according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing an outline of a conventional power cable termination structure.

[Problem to be solved by this disclosure]
It is desirable to develop a termination structure for a power cable that is highly productive. Specifically, it is desirable to prevent the end of the conductor from locally bending due to compression when mechanically connecting the connection terminal and the end of the cable conductor. In particular, it is desirable to efficiently perform a series of operations from compressing the connection terminal to compressing the pre-molded insulation by a compression device.

One of the objectives of this disclosure is to provide a termination connection structure for a power cable that is highly productive.

[Effects of the present disclosure]
The power cable termination structure according to the present disclosure has excellent productivity.

Description of the embodiments of the present disclosure
First, the embodiments of the present disclosure will be listed and described.

(1) A terminal connection structure for a power cable according to one aspect of the present disclosure includes:
a power cable having an end of a conductor exposed from an insulating layer;
a sleeve provided around the outer periphery of the end of the conductor;
A stress cone provided on the outer periphery of the insulating layer;
an electrode provided on an outer periphery of the sleeve;
the sleeve has a first connection portion and a second connection portion in this order in a direction from the front end to the rear end of the end of the conductor,
the first connection portion is mechanically connected to the end of the conductor by being compressed;
The second connection portion electrically connects the conductor and the electrode without being compressed.

The above-mentioned power cable termination connection structure has excellent productivity. The reason is that the sleeve has a first connection portion and a second connection portion in the direction from the tip to the rear end of the conductor end, which can suppress an increase in the number of steps required to manufacture the above-mentioned power cable termination connection structure. The details of the reason are as follows.

In the above-mentioned conventional power cable connection part, the connection terminal corresponding to the sleeve has a tubular portion corresponding to the first connection part and an axial portion corresponding to the second connection part. The sleeve in the conventional power cable connection part has the second connection part and the first connection part in the direction from the tip to the rear end of the conductor end. The conventional power cable connection part is usually manufactured in the order of a first step and a second step. In the first step, the end of the conductor and the first connection part are connected. First, a sleeve is fitted on the outer periphery of the end of the conductor. Next, the first connection part and the end of the conductor inside the first connection part are compressed from the outer periphery of the first connection part using a compression die. This compression connects the end of the conductor and the first connection part. In the second step, the second connection part and the electrode are connected by fitting the electrode on the outer periphery of the second connection part.

The compression in the first step may cause the end of the conductor to bend locally. When the end of the conductor is bent locally, the central axis of the part located at the tip of the first connection part and the central axis of the part located at the rear end are not coaxial. That is, the central axis of the part located at the tip and the central axis of the part located at the rear end are misaligned. When the second connection part and the first connection part are provided in order in the direction from the tip to the rear end of the end of the conductor as in the conventional case, the central axis of the second connection part and the central axis of the end of the insulating layer are not coaxial. That is, the central axis of the second connection part and the central axis of the end of the insulating layer are misaligned. When the end of the conductor is bent locally, an intermediate step may have to be performed between the first step and the second step. The intermediate step corrects the central axis of the second connection part and the central axis of the end of the insulating layer to be coaxial.

If the second step is carried out without going through the intermediate step, when the second connection part and the electrode are connected, the central axis of the second connection part and the central axis of the end of the insulating layer will remain misaligned. A stress cone is provided on the outer periphery of the end of the insulating layer. If the central axis of the second connection part and the central axis of the end of the insulating layer are misaligned, it will be difficult to apply uniform surface pressure over the entire length of the interface between the insulating layer and the stress cone, as will be described in more detail below. If the surface pressure becomes uneven, the insulation strength will decrease.

On the other hand, when the intermediate step and the second step are performed in order, the central axis of the second connection part and the central axis of the end of the insulating layer are coaxial when the second connection part and the electrode are connected. When the central axis of the second connection part and the central axis of the end of the insulating layer are coaxial, it is possible to apply a uniform surface pressure over the entire length of the interface between the insulating layer and the stress cone, as will be described in more detail below.

As explained above, in order to suppress the decrease in insulation strength, it is necessary to go through an intermediate process. However, going through an intermediate process increases the number of processes required to manufacture the termination connection structure of the power cable. The increase in the number of processes reduces the productivity of the termination connection structure of the power cable.

When the conductor end has a first connection portion and a second connection portion in that order in the direction from the tip to the rear end as described above, even if the end of the conductor is locally bent due to compression in the first step, there is no need to go through the intermediate step. This is because even if the end of the conductor is locally bent, the central axis of the second connection portion and the central axis of the end of the insulating layer remain coaxial. In other words, the central axis of the second connection portion and the central axis of the end of the insulating layer do not shift. Therefore, the second step can be carried out without going through the intermediate step.

(2) In the above-mentioned power cable termination structure,
The sleeve may have a through hole in which the end of the conductor is disposed.

The sleeve having a through hole makes it easier to carry out the first step compared to when the sleeve has a blind hole. This is because the compression work can be carried out while viewing the tip of the conductor end from outside the sleeve. Therefore, the termination connection structure of the power cable described above makes it easier to improve productivity.

Details of the embodiments of the present disclosure
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will now be described in detail with reference to the accompanying drawings, in which like reference numerals refer to like objects.

<<Embodiment>>
[Power cable termination structure]
With reference to FIG. 1, the power cable termination structure 1 of the embodiment will be described. The power cable termination structure 1 of the present embodiment includes a power cable 2, a sleeve 3, a stress cone 4, and an electrode 5. The power cable 2 has an end 21a of the conductor 21 exposed from the insulating layer 22. The sleeve 3 is provided on the outer periphery of the end 21a of the conductor 21. The stress cone 4 is provided on the outer periphery of the insulating layer 22. The electrode 5 is provided on the outer periphery of the sleeve 3. The sleeve 3 has a first connection portion 31 and a second connection portion 32. The first connection portion 31 is mechanically connected to the end 21a of the conductor 21 by being compressed. The second connection portion 32 electrically connects the conductor 21 and the electrode 5 without being compressed. One of the features of the power cable termination structure 1 of the present embodiment is that the first connection portion 31 and the second connection portion 32 are provided in order in a direction from the front end to the rear end of the end 21a of the conductor 21. A detailed description will be given below.

The power cable termination connection structure 1 of this embodiment is a gas termination connection structure for a power cable. Figure 1 shows a cross section of a part of the power cable termination connection structure 1 cut along a plane along the axial direction of a power cable 2 provided in the power cable termination connection structure 1. For convenience of explanation, in Figure 1, the stress cone 4, the electrode 5, and a stopper 9 described later are shown in half cross section. These points are the same in Figure 2 described later.

[Power cable]
The power cable 2 has a conductor 21 and an insulating layer 22. The insulating layer 22 is provided on the outer periphery of the conductor 21. Although not shown, the power cable 2 further includes, for example, a semiconductive layer, a shielding layer, and a sheath. The semiconductive layer is at least one of an inner semiconductive layer disposed between the conductor 21 and the insulating layer 22, and an outer semiconductive layer disposed between the insulating layer 22 and the shielding layer. A specific power cable 2 is a CV cable (crosslinked polyethylene insulated vinyl sheath cable). A known configuration can be used for the power cable 2. An end of the power cable 2 is step-stripped. By this step-stripping, the end 21a of the conductor 21 and the end 22a of the insulating layer 22 are each exposed.

[sleeve]
The sleeve 3 connects the power cable 2 to the electrode 5 described later. The sleeve 3 has a cylindrical shape. The sleeve 3 in this embodiment has a hole 30. The end 21a of the conductor 21 is disposed inside the hole 30. The hole 30 in this embodiment is a through hole. The through hole is provided along the axial direction of the power cable 2. Unlike this embodiment, the hole 30 may be a blind hole. The material of the sleeve 3 is a metal having excellent electrical conductivity. The metal is, for example, copper, a copper alloy, aluminum, or an aluminum alloy. The material of the sleeve 3 may be the same material as the conductor 21 among these metals, for example, in terms of electrical conductivity and ease of mechanical connection with the conductor 21. For example, when the material of the conductor 21 is copper, the material of the sleeve 3 may be copper, and when the material of the conductor 21 is aluminum, the material of the sleeve 3 may be aluminum. The sleeve 3 has a first connection portion 31 and a second connection portion 32.

(First connection part/second connection part)
The first connection portion 31 is compressed and mechanically connected to the end portion 21 a of the conductor 21. This mechanical connection fixes the end portion 21 a of the conductor 21 to the sleeve 3. The first connection portion 31 has an inner circumferential surface and an outer circumferential surface. The inner circumferential surface is in direct contact with the conductor 21. The outer circumferential surface is not in contact with the electrode 5. In other words, there is a gap between the outer circumferential surface and the inner circumferential surface of the electrode 5.

The second connection portion 32 electrically connects the conductor 21 and the electrode 5 without being compressed. The second connection portion 32 has an inner peripheral surface and an outer peripheral surface. In this embodiment, the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31 are flush with each other. In this embodiment, the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31 are continuous without any steps. Unlike this embodiment, the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31 may not be flush with each other, and there may be a step between the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31. Of course, it is better that the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31 are flush with each other, and that the inner peripheral surface of the second connection portion 32 and the inner peripheral surface of the first connection portion 31 are continuous without any steps, as in this embodiment. The inner peripheral surface is in direct contact with the conductor 21. In this embodiment, the outer diameter of the second connection part 32 is larger than the outer diameter of the first connection part 31 after compression. The outer peripheral surface is indirectly in contact with the electrode 5. In this embodiment, the outer peripheral surface of the second connection part 32 and the inner peripheral surface of the electrode 5 are in contact with each other via a multi-point contact type contact member (not shown). This contact member is, for example, a Multilamband manufactured by Staubli Electrical Connectors. The second connection part 32 and the electrode 5 are also mechanically connected in the radial direction by this contact member. By this mechanical connection, the central axis of the second connection part 32 is fixed to the central axis of the electrode 5. The central axis of the second connection part 32 is coaxial with the central axis of the end part 22a of the insulating layer 22.

The first connection portion 31 is provided at a position closer to the tip of the end 21a of the conductor 21 than the second connection portion 32, i.e., at the top in Fig. 1. By providing the first connection portion 31 at a position closer to the tip of the end 21a of the conductor 21 than the second connection portion 32, as will be described in detail later, an increase in the number of steps required to manufacture the power cable termination connection structure 1 can be suppressed. Therefore, the power cable termination connection structure 1 has excellent productivity.

[Stress cone]
The stress cone 4 relieves the electric field at the end of the power cable 2. The stress cone 4 is provided on the outer periphery of the end 22a of the insulating layer 22. Although not shown, the stress cone 4 has an electric field relief portion made of a semiconductive material. The stress cone 4 is attached to the power cable 2 so that this electric field relief portion covers the outer periphery of the outer semiconductive layer and is connected to the outer semiconductive layer.

Although not shown, the stress cone 4 is pressed toward the tip of the end 21a of the conductor 21 by a compression device. A known compression device can be used as the compression device. This pressing causes the stress cone 4 to abut against the stopper 9. The stopper 9 determines the position of the stress cone 4 relative to the end 22a of the insulating layer 22. The stopper 9 is disposed in the step portion 51 of the electrode 5 described later. As described above, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 are coaxial. Therefore, the stress cone 4 is easily compressed uniformly along the axial direction of the power cable 2 by the compression device and the stopper 9. The stress cone 4 is in close contact with the outer peripheral surface of the end 22a of the insulating layer 22 over its entire length. A predetermined surface pressure acts uniformly over the entire length on the interface between the stress cone 4 and the end 22a of the insulating layer 22.

The material of the stress cone 4 is, for example, ethylene propylene rubber or silicone rubber. The stress cone 4 may have a known configuration.

[electrode]
The electrode 5 electrically connects the power cable 2 to an external connection object (not shown). The external connection object is, for example, an electric power device. Although not shown, a bushing is provided on the outer periphery of the electrode 5. The bushing is made of, for example, epoxy resin. A known bushing can be used as the bushing.

The material of the electrode 5 is, for example, the same metal as the sleeve 3. That is, the material of the electrode 5 is copper, a copper alloy, aluminum, or an aluminum alloy. The material of the electrode 5 may be the same as or different from the material of the sleeve 3. The material of the electrode 5 may be an aluminum alloy among these metals in terms of weight reduction and cost reduction. The electrode 5 is composed of a rod-shaped member. The electrode 5 has a hole 50. The hole 50 has an opening facing the power cable 2. The sleeve 3 is disposed inside the hole 50. In this embodiment, the hole 50 is a blind hole. In this embodiment, a step 51 is provided at the opening of the hole 50. The step 51 positions the stopper 9 described above.

[Production method]
The power cable termination structure 1 of this embodiment is manufactured through a first step and a second step in order. In the first step, the end 21a of the conductor 21 is connected to the first connection portion 31. First, the sleeve 3 is fitted to the outer periphery of the end 21a of the conductor 21. Next, the first connection portion 31 and the end 21a of the conductor 21 inside the first connection portion 31 are compressed from the outer periphery of the first connection portion 31 using a compression die. This compression connects the end 21a of the conductor 21 to the first connection portion 31. As described above, since the hole portion 30 of the sleeve 3 is a through hole, the first step is easier to perform than when it is a blind hole. This is because the compression work can be performed while viewing the tip of the end 21a of the conductor 21 from the outside of the sleeve 3. Therefore, the productivity of the power cable termination structure 1 is easily improved. In the second step, the second connection portion 32 is connected to the electrode 5. The electrode 5 is fitted onto the outer periphery of the second connection portion 32 , whereby the second connection portion 32 and the electrode 5 are connected to each other.

The compression in the first step may cause the end 21a of the conductor 21 to bend locally. Since the first connection portion 31 is located closer to the tip of the end 21a of the conductor 21 than the second connection portion 32, even if the end 21a of the conductor 21 is bent locally, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 remain coaxial. This is because the second connection portion 32 is located closer to the rear end of the end 21a of the conductor 21 than the first connection portion 31. In other words, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 do not shift. Therefore, after the first step and the second step are sequentially performed, when the second connection portion 32 and the electrode 5 are connected, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 remain coaxial. As described above, since the central axis of the second connection portion 32 and the central axis of the end portion 22a of the insulating layer 22 are coaxial, it is possible to apply a uniform surface pressure over the entire length of the interface between the insulating layer 22 and the stress cone 4. The uniform surface pressure suppresses a decrease in insulation strength.

On the other hand, in the conventional power cable termination structure 100 shown in FIG. 2, the second connection portion 32 is provided at a position closer to the tip of the end 21a of the conductor 21 than the first connection portion 31. In this case, if the end 21a of the conductor 21 is locally bent due to compression in the first step, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 will be misaligned. Therefore, an intermediate step may be required between the first step and the second step. The intermediate step corrects the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 so that they are coaxial. If the second step is performed without the intermediate step, the central axis of the second connection portion 32 and the central axis of the end 22a of the insulating layer 22 will remain misaligned when the second connection portion 32 and the electrode 5 are connected. If the central axis of the second connection portion 32 is misaligned with the central axis of the end portion 22a of the insulating layer 22, the compression device and the stopper 9 cannot compress the stress cone 4 uniformly along the axial direction of the power cable 2. This makes it difficult to apply a uniform surface pressure over the entire length of the interface between the insulating layer 22 and the stress cone 4. If the surface pressure becomes non-uniform, the insulation strength decreases.

The power cable termination structure 1 of this embodiment has excellent productivity. The reason is as follows. In the power cable termination structure 1 of this embodiment, the sleeve 3 has a first connection portion 31 and a second connection portion 32 in the direction from the tip to the rear end of the end 21a of the conductor 21. Therefore, the power cable termination structure 1 of this embodiment can suppress an increase in the number of steps for manufacturing the power cable termination structure 1, compared to a conventional structure in which the sleeve 3 has the second connection portion 32 and the first connection portion 31 in the direction from the tip to the rear end of the end 21a of the conductor 21.

The present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1, 100 Power cable termination structure 2 Power cable 21 Conductor, 21a End, 22 Insulating layer, 22a End 3 Sleeve, 30 Hole, 31 First connection portion, 32 Second connection portion 4 Stress cone, 5 Electrode, 50 Hole, 51 Step portion 9 Stopper

Claims (2)

a power cable having an end of a conductor exposed from an insulating layer;
a sleeve provided around the outer periphery of the end of the conductor;
A stress cone provided on the outer periphery of the insulating layer;
an electrode provided on an outer periphery of the sleeve;
the sleeve has a first connection portion and a second connection portion in this order in a direction from the front end to the rear end of the end of the conductor,
the first connection portion is mechanically connected to the end of the conductor by being compressed;
the second connection portion electrically connects the conductor and the electrode without being compressed;
A termination structure for a power cable. The power cable termination structure of claim 1, wherein the sleeve has a through hole in which the end of the conductor is disposed.

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