JPH089546A - Resistance terminal part of cable - Google Patents

Abstract

PURPOSE:To protect stably in a long term the terminal of a cable, when its resistance terminal is formed. CONSTITUTION:Between an insulator 5 and a semiconductor layer 12 so formed as to cover the part ranged from a shielding layer 3 to a conductor 6, a heat- insulating layer 11 made of a glass fiber tape, etc., is formed. Therefore, the insulator 5 is not affected by the heat generation of the semiconductor layer 12 which is caused by leakage currents and charge-discharge currents. Also, when the outer diameter of the semiconductor layer 12 is made large step by step as it approaches the shielding layer 3 from the conductor 6, the potential distribution along the peripheral surface of the semiconductor layer 12 is made uniform, and thereby, the characteristic of the resistance terminal part of a cable is made stable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance termination portion of a cable formed at a terminal such as a DC high voltage cable.

[0002]

2. Description of the Related Art As a method of forming a terminal portion of a cable, a method of using a stress cone, a method of using a capacitor cone, a method of forming a resistance termination and the like are known. In the case of a cable that applies a DC ultra-high voltage or a cable that supplies high-voltage repetitive pulses, reinforcement of insulation at the end of the cable is inevitable. The end portion using the above stress cone or condenser cone is relatively large in size because it is housed inside a tube made of insulator or epoxy resin and filled with insulating oil or insulating gas. It also takes time to assemble. On the other hand, the resistance termination has an advantage that the structure is relatively simple and the weight can be reduced.

FIG. 2 shows a vertical sectional view of a resistance termination portion of a conventional cable. The illustrated cable 1 includes a sheath 2, a shield layer 3,
The semiconductive layer 4 and the insulator 5 are peeled off in order to expose the conductor 6 from one end thereof. The shield layer 3 is previously peeled off from the end of the cable 1 so that the insulator 5 is exposed for a predetermined length. Then, a semi-conductive layer 7 is provided which passes from the peeled end 3A of the shielding layer 3 over the insulator 5 and surrounds from the end of the insulator to the exposed conductor 6.

The semiconductive layer 7 is formed by winding a semiconductive rubber or a plastic tape. by this,
The shielding layer 3 and the conductor 6 are electrically connected by the semiconductive layer 7 having a high resistance, and a constant potential distribution corresponding to the resistance is generated therebetween. As a result, the distribution of electric lines of force around the periphery is made uniform.

[0005]

By the way, the conventional resistance termination portion of the cable as described above has the following problems to be solved. A very small amount of current flows through the resistance termination as described above due to the high voltage applied between the shield layer 3 of the cable and the conductor 6. Further, when a high DC voltage is applied, a charging current and a discharging current flow. As a result, the semiconductive layer 7 heats up and the insulator 5 is deteriorated, which impedes the long-term stability of this type of terminal portion. The present invention has been made in view of the above points, and it is an object of the present invention to provide a resistance termination portion of a cable that achieves stable terminal protection.

[0006]

The resistance termination portion of the cable of the present invention passes over the insulator from the shield layer peeling end of the cable in which the shield layer is peeled off at the end to expose the insulator for a predetermined length, A resistance termination member surrounding the insulator end portion to the exposed conductor, the resistance termination member comprising a semiconductive layer continuously formed from the shield layer to the conductor, and the semiconductive layer. And a heat insulating layer formed between the layer and the outer surface of the insulator.

[0007]

In this resistance termination portion, a heat insulating layer made of glass fiber tape or the like is formed between the insulator and the semiconductive layer formed so as to cover the shield layer and the conductor. Therefore, the heat generated in the semiconductive layer due to the leakage current or the charge / discharge current does not reach the insulator. When the outer diameter of the semiconductive layer becomes thicker as it gets closer to the shield layer from the conductor, the potential distribution along the peripheral surface of the semiconductive layer becomes uniform and the characteristics are stabilized.

[0008]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1A and 1B show an embodiment of a resistance termination portion of a cable of the present invention. FIG. 1A is a vertical sectional view thereof, and FIG. 1B is a side view thereof. In the figure, the cable 1, like the conventional one, has a sheath 2, a shield layer 3, a semiconductive layer 4, and an insulator 5 which are sequentially peeled off to expose a conductor 6 from one end thereof. In such a terminal, in the present invention, the semiconductive layer 4 of the cable,
A heat insulating material layer 11 is formed so as to cover the insulator 5. The heat insulating material layer 11 is made of a heat insulating insulating tape such as a glass fiber tape.

A semiconductive layer 12 is formed on the outer periphery of the heat insulating material layer 11.
To form. The thermal insulation material layer 11 and the semiconductive layer 12 form the resistance termination member 10. In this embodiment, the semiconducting layer 12 is made of, for example, a carbon fiber woven tape and is formed by winding such a tape in many layers. The outer diameter of the semiconductive layer 12 is
In this embodiment, as shown in FIG. 3B, the thickness of the layer is selected so that the outer diameter becomes larger as the conductor 6 gets closer to the shielding layer 3. That is, the portion closest to the conductor 6 has the outer diameter D.
1, the middle portion has the outer diameter D2, and the portion closest to the shielding layer 3 has the outer diameter D3. In this example, the outer diameter is selected in three stages. The relationship between the outer diameters D1, D2 and D3 is as follows. D1 <D2 <D3 Specifically, the electric resistance of the semiconductive layer 12 is set to 1 to 10
Set like Ω / V. That is, corresponding to the voltage applied to both ends of the semiconductive layer 12, the resistance value is selected to be 1 to 10 Ω when the voltage is applied 1 V and 1000 times the resistance value when the voltage is applied 1 kV. Also, its length is 250 kVp
It may be set to about / m. That is, the maximum value per meter is 25
The length is selected so that a voltage of about 0 kV is applied.

With the above-described structure, the resistance termination portion of the cable of the present invention generates heat even when a leakage current or a charging / discharging current flows in the semiconductive layer 12 due to a high voltage. However, since the insulator 5 is protected by the heat insulating material layer 11, there is no fear that the electrical characteristics of the insulator 5 will deteriorate even after long-term use.

Further, when the thickness of the semiconductive layer 12 is selected so that the outer diameter becomes thicker from the conductor to the shielding layer, the tapered surface formed by the semiconductive layer 12 is just from the conductor to the shielding layer. Is formed. By doing so, the distribution of the lines of electric force can be made more uniform at both ends as compared with the case where the semiconductive layer 12 having the same outer diameter is formed over the entire length, and the occurrence of creeping discharge or the like can be prevented.

The present invention is not limited to the above embodiments. The heat insulating material layer 11 may be made of a heat insulating tape or film, paint, or the like.
2 is also a tape or film having a predetermined semiconductivity,
It can be formed of paint, resin, or the like. In addition, the outer diameter of the semiconductive layer can be selected as appropriate according to the voltage used, the surface condition of the material, the environment in which it is used, etc. It is preferable that the ratio of the minimum outer diameter to the minimum outer diameter is experimentally determined according to the environment and conditions of use. Of course, the tape may be wound so as to smoothly increase the outer diameter.

[0013]

The resistance termination portion of the cable of the present invention described above passes over the insulator from the shield layer peeling end of the cable in which the shield layer is peeled off at the end to expose the insulator for a predetermined length, and the insulator end. A semi-conducting layer formed of a resistance terminating member that surrounds the conductor to the exposed conductor and formed continuously from the shielding layer to the conductor; and a heat insulating material layer formed between this and the outer surface of the insulator. Since it is composed of, it is difficult for heat generated by leakage current of the semi-conductive layer to be transmitted to the insulator of the cable,
It is possible to protect the insulator of the cable and achieve long-term stability of the characteristics of the end portion. Further, if the thickness is selected so that the outer diameter becomes thicker as it gets closer to the shield layer from the conductor, the potential distribution on the outer surface of the semiconductor layer is relaxed, and a resistance termination portion having good characteristics can be obtained.

[Brief description of drawings]

FIG. 1 shows an embodiment of a resistance termination portion of a cable of the present invention,
(A) is a longitudinal sectional view and (b) is a side view.

FIG. 2 is a vertical cross-sectional view showing a resistance termination portion of a conventional cable.

[Explanation of symbols]

 1 Cable 2 Sheath 3 Shielding Layer 3A Shielding Layer Exfoliated Edge 4 Semiconductive Layer 5 Insulator 6 Conductor 10 Resistive Termination Member 11 Insulation Material Layer 12 Semiconductive Layer

Claims (2)

[Claims] 1. A cable, which has a shield layer peeled off at a terminal end to expose an insulator for a predetermined length, passes from the shield layer peeled end, passes through the insulator, and extends from the insulator end portion to an exposed conductor. Which comprises a semi-conductor layer formed continuously from the shielding layer to the conductor, and a heat insulation layer formed between the semi-conductor layer and the outer surface of the insulator. A resistive termination of a cable, which comprises a material layer. 2. The cable according to claim 1, wherein the thickness of the semiconductive layer is selected such that the outer diameter becomes thicker as the conductor gets closer to the shielding layer. Resistor termination.