JP2016144305A - Equipment direct connection terminal and cable connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the following problem: There has not conventionally been any apparatus direct connection terminal suitable for direct connection of a cable having an aluminum cable conductor with a bushing having a copper bushing conductor.SOLUTION: The apparatus direct connection terminal is used to directly connect a cable 3 having an aluminum cable conductor 5 with a bushing 4 having a copper bushing conductor 7, and includes: an aluminum connection terminal 8 electrically connected with the cable conductor 5 and the bushing conductor 7; a pressing member 9 for pressing the connection terminal 8 against the bushing conductor 7. The connection terminal 8 includes a wedge-like terminal part 12 in contact with the bushing conductor 7 and is formed with a copper plated layer 10 at an outer-peripheral surface 12a of the terminal part 12. The plated layer 10 is pressed against the bushing conductor 7 by a pressing force of the pressing member 9.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a device direct connection terminal and a cable connection structure.

  Conventionally, an apparatus direct connection terminal is used to directly connect a cable to a bushing on the electric apparatus side. A bushing is an insulating member used when connecting a cable to an electric device. The device direct connection terminal is attached to the end of the cable. When connecting a cable to the bushing, it is necessary to electrically connect (conduct) the conductor on the bushing side (hereinafter referred to as “bushing conductor”) and the conductor on the cable side (hereinafter referred to as “cable conductor”). is there. For this reason, the apparatus direct connection terminal is configured to include a connection terminal that is electrically connected to the cable conductor and the bushing conductor. As a cable connection structure using a device direct connection terminal, for example, the one described in Patent Document 1 is known.

  In general, the cable conductors that make up the cable core are often made of copper because of their excellent electrical conductivity and corrosion resistance, and the connection terminals and bushing conductors of equipment direct connection terminals are also made of copper. Is used. However, in recent years, the price of copper has soared, and there is a movement to adopt an aluminum conductor for the cable, which is cheaper than copper. In addition, since aluminum is lighter than copper, an aluminum conductor may be used for the cable in order to reduce the weight of the entire cable.

Japanese Patent Laid-Open No. 9-289049

  However, when adopting an aluminum conductor for a cable, there are the following problems. First, aluminum has a property that its surface is more easily oxidized than copper. For this reason, for example, when the connection terminal of the equipment direct connection terminal is made of aluminum in accordance with the cable conductor, the surface of the terminal is gradually oxidized by contact with oxygen in the atmosphere and finally covered with an oxide film of aluminum. End up. Then, when the cable is connected to the bushing, the electrical resistance between the bushing conductor and the connection terminal becomes high. For this reason, it becomes impossible to electrically connect (conduct) the bushing conductor and the cable conductor in a good state.

  The main object of the present invention is to provide a technology capable of electrically connecting both conductors in good condition when a cable having an aluminum cable conductor is directly connected to a bushing having a copper bushing conductor. There is to do.

The first aspect of the present invention is:
An apparatus direct connection terminal for directly connecting a cable having an aluminum cable conductor to a bushing having a copper bushing conductor,
An aluminum connection terminal electrically connected to the cable conductor and the bushing conductor;
A pressing member that presses the connection terminal against the bushing conductor;
With
The connection terminal has a wedge-shaped terminal portion that contacts the bushing conductor, and a copper plating layer is formed on a contact surface of the terminal portion with respect to the bushing conductor, and the plating layer exerts a pressing force of the pressing member. A device direct connection terminal characterized by being configured to be received and pressed against the bushing conductor.

The second aspect of the present invention is:
A cable connection structure in which a cable having an aluminum cable conductor is connected to a bushing having a copper bushing conductor using a device direct connection terminal,
The device direct connection terminal is:
An aluminum connection terminal electrically connected to the cable conductor and the bushing conductor;
A pressing member that presses the connection terminal against the bushing conductor;
With
The connection terminal has a wedge-shaped terminal portion that contacts the bushing conductor, and a copper plating layer is formed on a contact surface of the terminal portion with respect to the bushing conductor, and the plating layer exerts a pressing force of the pressing member. The cable connection structure is characterized by being received and pressed against the bushing conductor.

  According to the present invention, when a cable having an aluminum cable conductor is directly connected to a bushing having a copper bushing conductor, both conductors can be electrically connected in good condition.

It is a fragmentary sectional view which shows the structural example of the principal part of the apparatus direct connection terminal which concerns on embodiment of this invention. It is the figure which expanded a part of FIG. It is a figure explaining the structure of a connection terminal. It is a figure explaining the structure of a pressing member. It is a figure which shows the state which attached the pressing member to the connection terminal. It is a figure which shows the state which pressed the connection terminal with the pressing member.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<Device direct connection terminal>
FIG. 1 is a partial cross-sectional view showing a configuration example of a main part of a device direct connection terminal according to an embodiment of the present invention, and FIG.
The illustrated device direct connection terminal 1 is for directly connecting a cable 3 to a bushing 4 connected to an electric device. Examples of the electric device include a transformer, a circuit breaker, and a switch. The cable 3 is constituted by a power cable such as a CV cable (cross-linked polyethylene insulated vinyl sheath cable). The bushing 4 is an insulating member used when connecting a cable to an electric device.

  The cable 3 includes at least a cable conductor 5 constituting a core wire and a cable insulator 6 that covers the cable conductor 5. At the end of the cable 3, the cable insulator 6 is removed and the cable conductor 5 is exposed. The cable conductor 5 is configured using an aluminum conductor. As used herein, “made of aluminum” refers to those made of aluminum or an aluminum alloy. The cable insulator 6 is formed outside the cable conductor 5 so as to cover it.

  The apparatus direct connection terminal 1 includes a connection terminal 8 and a pressing member 9. The connection terminal 8 is electrically connected to the cable conductor 5 included in the cable 3 and the bushing conductor 7 included in the bushing 4. The connection terminal 8 is the same aluminum terminal as the cable conductor 5 described above.

  The connection terminal 8 is formed in a cylindrical shape as a whole. A cable receiving hole 11 (see FIG. 2) through which the cable conductor is inserted is formed inside the connection terminal 8. The cable receiving hole 11 is a hole having a circular cross section corresponding to the outer diameter of the cable conductor 5. The cable receiving hole 11 is formed on the central axis of the connection terminal 8 so as to penetrate the connection terminal 8.

  The connection terminal 8 integrally includes a wedge-shaped terminal portion 12, a groove portion 13, a flange portion 14, and a straight portion 15. The terminal portion 12 is a portion that contacts the bushing conductor 7. The outer peripheral surface 12a of the terminal portion 12 is a tapered surface that decreases in diameter (the outer diameter decreases) toward the distal end side (left side in FIG. 2) of the connection terminal 8. The outer peripheral surface 12 a is a contact surface of the terminal portion 12 with respect to the bushing conductor 7.

  A copper plating layer 10 (see FIG. 2) is formed on the outer peripheral surface (tapered surface) 12 a of the terminal portion 12. The plated layer 10 is formed so as to cover the outer peripheral surface 12 a of the terminal portion 12. Further, the plating layer 10 is formed in close contact with an underlying ground such as aluminum which is the main material of the connection terminal 8. The plated layer 10 is formed on the outer peripheral surface 12a of the terminal portion 12 so as to cover at least a region in contact with the bushing conductor 7. The plating layer 10 is preferably formed by so-called copper thick plating so that the plating thickness is increased to some extent. The thickness of the plating layer 10 is preferably 150 mm or more, more preferably 200 mm or more, and even more preferably 250 mm or more. The groove portion 13 is formed between the terminal portion 12 and the flange portion 14 in the length direction of the connection terminal 8. The outer peripheral surface of the flange portion 14 is inclined in the direction opposite to the outer peripheral surface 12 a described above with respect to the central axis of the connection terminal 8. The straight portion 15 is formed on the rear end side of the connection terminal 8.

  Further, as shown in FIG. 3, a plurality of slits 16 are formed in the connection terminal 8. These slits 16 are for enabling the connection terminal 8 to be deformed (reduced) inward by the pressure when the connection terminal 8 receives pressure from the outside in the direction of diameter reduction. Each slit 16 is formed in parallel with the central axis direction of the connection terminal 8. Further, the slit 16 is formed by cutting from the front end side and the rear end side of the connection terminal 8.

  The pressing member 9 presses the connection terminal 8 against the bushing conductor 7. The pressing member 9 is made of brass, for example, and is formed in a cylindrical shape as a whole. A circular fitting hole 21 (see FIG. 2) that fits with the straight portion 15 of the connection terminal 8 is formed inside the pressing member 9. The fitting hole 21 is formed on the central axis of the pressing member 9 so as to penetrate the pressing member 9.

  Further, the tip side of the pressing member 9 (left side in FIG. 2) is gradually reduced in thickness due to the presence of the pressing surface 22 inclined in a tapered shape. The inner diameter of the pressing surface 22 increases toward the tip side of the pressing member 9. Further, as shown in FIG. 4, a male screw portion 23 and a protruding portion 24 are formed on the outer peripheral surface of the pressing member 9. The male screw portion 23 is for screwing the pressing member 9 into the bushing conductor 7. The protruding portion 24 protrudes outward from the male screw portion 23 on the rear end side of the pressing member 9.

  The bushing 4 is made of, for example, a hard insulating resin such as an epoxy resin. A bushing conductor 7 is provided inside the bushing 4. The bushing conductor 7 constitutes, for example, a conductor lead bar connected to an electric device, and is integrated with the bushing 4 by molding of a resin constituting the bushing 4. The bushing conductor 7 is made of copper. “Copper” described in the present specification refers to one made of copper or a copper alloy. Inside the bushing conductor 7, an insertion hole 25 through which the terminal portion 12 of the connection terminal 8 is inserted, and a female screw portion 26 corresponding to the male screw portion 23 of the pressing member 9 are formed. The inner peripheral surface 25 a of the insertion hole 25 is a tapered surface that decreases in diameter toward the back side (left side in FIG. 2) of the insertion hole 25. The female screw portion 26 is formed at the entrance portion of the opening that leads to the insertion hole 25.

The apparatus direct connection terminal 1 is manufactured through the following procedures, for example.
First, after the end of the cable 3 is processed to expose the cable conductor 5 and the cable insulator 6, the connection terminal 8 and the pressing member 9 are attached to the cable conductor 5. At this time, the connecting terminal 8 and the pressing member 9 are assembled as shown in FIG. 5 so that the fitting hole 21 of the pressing member 9 is fitted to the straight portion 15 of the connecting terminal 8. For connection between the connection terminal 8 and the cable conductor 5, a compound provided for compression connection is used. This compound is a mixture of grease as a main material and metal particles, and is used for the purpose of preventing electrolytic corrosion at connection parts and reducing electric resistance. In actual use, the aluminum surface of the cable conductor 5 and the connection terminal 8 is previously polished with a wire brush or the like before the work to remove the oxide film on the surface, and then an appropriate amount of compound is applied to the cable receiving hole 11 of the connection terminal 8 After application, the cable conductor 5 is inserted into the cable receiving hole 11 in this state.

  Next, the terminal portion 12 of the connection terminal 8 is inserted into the insertion hole 25 of the bushing conductor 7. Next, the male screw portion 23 of the pressing member 9 is screwed into the female screw portion 26 of the bushing conductor 7. When the pressing member 9 is rotated in this state, the pressing member 9 moves toward the back side of the insertion hole 25.

  Therefore, first, the pressing member 9 is rotated until the pressing surface 22 of the pressing member 9 abuts against the flange portion 14 of the connection terminal 8. Next, the pressing member 9 is further tightened in the rotating direction under the abutting state. Then, the connection terminal 8 is pushed into the back side of the insertion hole 25 by the pressing member 9 while the pressing surface 22 is in contact with the flange portion 14. In this case, since the outer peripheral surface 12a of the terminal portion 12 of the connection terminal 8 and the inner peripheral surface 25a of the insertion hole 25 of the bushing conductor 7 are each gently inclined in a tapered shape, the terminal portion 12 of the connection terminal 8 is The bushing conductor 7 is pushed by the wedge principle. For this reason, when the connection terminal 8 is pressed by the pressing member 9, the outer peripheral surface 12 a of the terminal portion 12 comes into close contact with the inner peripheral surface 25 a of the insertion hole 25 as shown in FIG. 6. Further, a strong surface pressure is generated at the contact interface between the outer peripheral surface 12 a of the terminal portion 12 and the inner peripheral surface 25 a of the insertion hole 25.

  When the connection terminal 8 is pushed in by the pressing member 9 as described above, the terminal portion 12 of the connection terminal 8 receives a compressive force due to contact with the bushing conductor 7. For this reason, the connection terminal 8 tends to be deformed inward due to the presence of the slit 16 described above. However, the cable conductor 5 is inserted into the cable receiving hole 11 of the connection terminal 8. For this reason, when the pressing member 9 is pressed as described above, the inner peripheral surface of the cable receiving hole 11 comes into close contact with the outer peripheral surface of the cable conductor 5 due to the compressive force. Further, the connection terminal 8 is substantially compressed and connected to the cable conductor 5.

  Thereby, the connection terminal 8 is electrically connected to both the cable conductor 5 and the bushing conductor 7. Further, the bushing conductor 7, the connection terminal 8, and the pressing member 9 are integrally coupled by a surface pressure or a compressive force generated by the principle of the wedge.

  In this case, the bushing conductor 7 and the connection terminal 8 are in contact with each other because the bushing conductor 7 is made of copper and the copper plating layer 10 is formed on the outer peripheral surface 12 a of the terminal portion 12. On the other hand, although the connection terminal 8 and the cable conductor 5 are in contact with each other, when the above-described compound is used, conduction between members can be achieved through the metal particles contained in the compound. For this reason, an increase in electrical resistance due to the oxide film of aluminum is suppressed. Further, the cable conductor 5 and the connection terminal 8 need to be made of the same conductive material. The reason is that if the cable conductor 5 and the connection terminal 8 are made of different conductive materials, a difference in the thermal expansion coefficient due to the difference in the conductive material may cause a decrease in compressive force due to a temperature change, thereby preventing this. . For this reason, in this Embodiment, the connection terminal 8 made from aluminum is connected with the cable conductor 5 made from aluminum.

<Effect of Embodiment>
According to the present embodiment, one or more effects shown below can be obtained.

  In the present embodiment, the aluminum connection terminal 8 and the copper bushing conductor 7 are electrically connected via the copper plating layer 10 formed on the outer peripheral surface 12 a of the terminal portion 12. For this reason, when the cable 3 is directly connected to the bushing 4 using the device direct connection terminal 1, the electrical connection between the bushing conductor 7 and the connection terminal 8 is made substantially by contact between copper. Accordingly, when the cable 3 having the aluminum cable conductor 5 is directly connected to the bushing 4 having the copper bushing conductor 7, both conductors can be electrically connected in a good state.

  In the present embodiment, the plating layer 10 on the outer peripheral surface 12 a of the terminal portion 12 is configured to be pressed against the bushing conductor 7 by receiving the pressing force of the pressing member 9. For this reason, the plating layer 10 of the connection terminal 8 can be strongly adhered to the inner peripheral surface 25 a of the bushing conductor 7. Thereby, a stable conduction state is obtained between the bushing conductor 7 and the connection terminal 8. Further, the conduction state between the bushing conductor 7 and the connection terminal 8 can be favorably maintained over a long period of time.

  In the present embodiment, the cable conductor 5 is inserted into the cable receiving hole 11 of the connection terminal 8, and the outer peripheral surface 12 a of the terminal portion 12 is brought into contact with the inner peripheral surface 25 a of the bushing conductor 7 on the outer side of the cable conductor 5. Yes. For this reason, the cable conductor 5, the connection terminal 8, and the bushing conductor 7 can be firmly coupled by the pressing force of the pressing member 9.

<Modifications>
The technical scope of the present invention is not limited to the above-described embodiments, and includes various modifications and improvements as long as the specific effects obtained by the constituent elements of the invention and combinations thereof can be derived.

  For example, in the above embodiment, the pressing member 9 is made of brass. However, the pressing member 9 is not limited to this, and the pressing member 9 may be made of copper or stainless steel, for example.

  Moreover, you may form the plating layer by silver plating or tin plating as needed on the surface of the bushing conductor 7. FIG. Moreover, you may form the plating layer by silver plating or tin plating as needed also on the copper plating surface of the connection terminal 8. FIG.

  As a method of forming the copper plating layer 10 on the connection terminal 8, any plating method such as electrolytic plating or electroless plating may be employed. When the connection terminal 8 is plated, the inner peripheral surface of the cable receiving hole 11 into which the cable conductor 5 is inserted may be masked. In this case, in addition to the outer peripheral surface 12a of the terminal portion 12, the surfaces of the groove portion 13 and the flange portion 14 are also plated, but there is no particular problem.

  The present invention is not only realized as the above-described device direct connection terminal 1, but also realized as a device direct connection terminal with a cable in a state where a cable is attached to the device direct connection terminal, or a cable having an aluminum cable conductor, It is also possible to realize a cable connection structure in which a bushing having a copper bushing conductor is connected using a device direct connection terminal.

DESCRIPTION OF SYMBOLS 1 ... Device direct connection terminal 3 ... Cable 5 ... Cable conductor 7 ... Bushing conductor 8 ... Connection terminal 9 ... Pushing member 10 ... Plating layer 11 ... Cable receiving hole 12 ... Terminal part 12a ... Outer peripheral surface

Claims (3)

An apparatus direct connection terminal for directly connecting a cable having an aluminum cable conductor to a bushing having a copper bushing conductor,
An aluminum connection terminal electrically connected to the cable conductor and the bushing conductor;
A pressing member that presses the connection terminal against the bushing conductor;
With
The connection terminal has a wedge-shaped terminal portion that contacts the bushing conductor, and a copper plating layer is formed on a contact surface of the terminal portion with respect to the bushing conductor, and the plating layer exerts a pressing force of the pressing member. A device direct connection terminal characterized by being configured to be received and pressed against the bushing conductor. The connection terminal is formed in a cylindrical shape having a cable receiving hole through which the cable conductor is inserted, and the outer peripheral surface of the terminal portion is a tapered surface whose diameter is reduced toward the distal end side of the connection terminal. The device direct connection terminal according to claim 1, wherein the plating layer is formed on the tapered surface. A cable connection structure in which a cable having an aluminum cable conductor is connected to a bushing having a copper bushing conductor using a device direct connection terminal,
The device direct connection terminal is:
An aluminum connection terminal electrically connected to the cable conductor and the bushing conductor;
A pressing member that presses the connection terminal against the bushing conductor;
With
The connection terminal has a wedge-shaped terminal portion that contacts the bushing conductor, and a copper plating layer is formed on a contact surface of the terminal portion with respect to the bushing conductor, and the plating layer exerts a pressing force of the pressing member. A cable connection structure, wherein the cable connection structure is pressed against the bushing conductor.

Images