JPH10201070A - Method of detecting abnormality of cv cable termination part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detector which can quickly detect the condition that the cable shield layer of the termination part of a CV cable has floated. SOLUTION: An electrode 5 is attached to the periphery of the termination part 3 to connect a CV cable 1 with a terminal. The electrode 5 is attached in the position opposed to the cable shield layer to cover the stress cone of the termination part. If a crack occurs in the cable shield layer of the termination part and the cable shield layer floats, voltage is induced in the cable shield layer and the electrode for detection from the cable conductor. When this voltage is detected by an abnormality diagnoser 6, it is judged that float has occurred in the cable shield layer of the termination part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting an abnormality of a cable shield layer in a terminal processing section of a CV cable.

[0002]

2. Description of the Related Art In a power CV cable terminal processing unit, a shield layer A is wound around an outer periphery of a stress cone as a cable shield layer. This shield layer A is
At its end, it overlaps with the end of the shield layer B, which is the shield layer in the cable body, and is electrically connected. Further, a ground lead wire is drawn out of the cable from the shield layer B. As a result, the portion from the cable body to the turning point of the stress cone of the terminal processing section becomes a cable shield layer of the ground potential.

In the terminal processing section of the CV cable having the above structure, the cable shield layer including the shield layer A and the shield layer B may be broken due to poor construction, stress due to temperature fluctuation, and the like. When a rupture occurs, the portion cut off from the grounded cable shield layer floats from the ground potential, so that a voltage is induced from the cable conductor. Thereby, a spark discharge or a partial discharge occurs between the float portion and the ground potential portion at the rupture portion.

When this spark discharge or partial discharge continues,
Degradation of insulation in the surrounding insulators progresses, and ultimately dielectric breakdown occurs. In order to prevent the occurrence of the dielectric breakdown, a spark discharge or a partial discharge is detected to obtain a CV.
A method for detecting an abnormality of a cable terminal processing unit has been proposed. As a method therefor, a method has been proposed in which an electromagnetic wave generated by spark discharge or partial discharge is detected by an antenna. Alternatively, place the test cable in a power outage state, connect a high voltage test power supply and a coupling capacitor to the test cable,
A method for detecting a partial discharge pulse has been proposed.

[0005]

However, in the above-mentioned conventional method, even if a tear occurs and a part of the cable shield layer floats, an abnormality cannot be detected unless partial discharge or spark discharge occurs. An object of the present invention is to provide an abnormality detection method that can quickly detect a state in which a cable shield layer of a CV cable terminal processing unit floats.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and detects an abnormality occurring in a terminal processing section of a CV cable having a shield layer covering an outer periphery of a stress cone. In performing the abnormality diagnosis, an electrode is attached to a portion of the outer peripheral portion of the terminal processing section facing the shield layer. The position where this electrode is attached is preferably a position facing the shield layer and is a position where the electrode reliably floats when a tear occurs.

When there is no abnormality in the terminal processing unit, no voltage is induced because this electrode is attached to face the shield layer at the ground potential. When a break occurs in the cable shield layer of the terminal processing section and the cable shield layer is separated from the grounded cable shield layer, the separated cable shield layer floats from the ground potential. A voltage is induced from the cable conductor.

Therefore, it is possible to diagnose whether or not an abnormality has occurred in the terminal processing section of the CV cable by measuring the voltage induced at the electrode. This diagnosis can be easily performed even when the cable is in a live state.

[0009]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an implementation status of an abnormality detection method of a terminal processing unit of a CV cable. In the figure, reference numeral 1 denotes a CV cable. 2 is a terminal provided at the tip of the CV cable 1. Reference numeral 3 denotes a terminal processing unit for connecting the CV cable 1 and the terminal 2. Reference numeral 4 denotes a ground lead wire having the CV cable 1 and the cable shield layer in the terminal processing unit 3 as ground potential.

Reference numeral 5 denotes a detection electrode (copper foil tape) attached to the outer periphery of the terminal processing unit 3. 6 is an abnormality diagnosis device. 7 and 8 are probes for connecting the detection electrode 5 and the ground potential to the abnormality diagnosis device 6. Reference numeral 9 denotes a power supply. As the power supply, a power supply that applies power to the cable is used when the diagnosis is performed in a live state of the cable. You.

FIG. 2 shows the details of the terminal processing unit. In FIG. 2, for easy understanding, a part is shown in a cross section and a part is shown in a state in which each element is cut open. The CV cable 1 includes a cable conductor 11, an insulator layer 12, a semiconductive layer 13, a shield layer B (copper foil tape layer) 14, and a sheath 15 sequentially formed on the outer periphery thereof.

In the terminal processing section 3, the CV cable 1
The semiconductive layer 13, the shield layer B14, and the sheath 15 are removed, and the cable conductor 11 and the insulator layer 12 are exposed. The stress cone 2 is formed around the outer periphery of the insulator layer 12.
1. A shield layer A (lead tape layer) 22 and a PVC tape layer 24 are formed. Note that an adhesive tape (adhesive polyethylene tape) 23 is wound around the outer periphery of the shield layer A22.

The shield layer A22 is formed from the tip of the semiconductive layer 13 to the turning point of the stress cone 21. A shield layer B14 is further formed outside the overlapping portion of the semiconductive layer 13 and the shield layer A22. The semiconductive layer 13, the shield layer A22, and the shield layer B14
A wire 31 is wound around the portion where the three layers are overlapped to ensure the potential fixation of the overlap portion of
Soldering is performed at the portion 32. Further, another wire 33 is wound around the shield layer B14, and
At 4, it is soldered and pulled out as a ground lead wire 4. Thereby, the shield layer B of the cable body
14 to the shield layer A2 at the turning point of the stress cone 21
Up to 2 is the ground potential.

In order to detect an abnormality in the terminal processing section 3, a shield layer A22 is formed on the surface of the PVC tape layer 24 of the terminal processing section 3.
The detection electrode 5 is attached to a position facing the. It is preferable that the position where the detection electrode 5 is attached is set as far as possible from the connection portion with the shield layer B14. In addition, the detection electrode 5 can be attached to the terminal processing unit 3 at all times, or can be attached each time a diagnosis is made. The detection electrode 5 is connected to an abnormality diagnosis device 6 as shown in FIG.

Next, an abnormality detection method will be described. FIG. 2 shows a state in which no abnormality has occurred in the terminal processing unit 3. In this state, since the shield layer A22 is at the ground potential, no voltage is induced on the detection electrode 5 arranged to face the shield layer A22. Therefore, the abnormality diagnosis device 6 does not detect the voltage.

FIG. 3 shows a state in which an abnormality has occurred in the terminal processing unit 3. The shield layer A22 or the shield layer B14 may be torn by stress due to poor construction, temperature fluctuation, or the like. FIG. 3 shows a state in which the fracture has occurred in the portion A of the shield layer A22. The shield layer A22 that has been torn and separated from the shield layer B14 floats from the ground potential. Thus, voltages are induced in the shield layer A22 and the detection electrode 5 by the voltage applied to the cable conductor 11, respectively.

The voltage induced on the detection electrode 5 is detected by the abnormality diagnosis device 6. Therefore, when the abnormality diagnosis device 6 detects the induced voltage, it can be determined that the cable shield layer is torn and a part of the cable shield layer has floated. The abnormality diagnosis device 6 may display an induced voltage, or may output an electric signal or the like when the induced voltage is detected.

Thus, it is possible to quickly detect an abnormality in the terminal processing section of the CV cable when a float occurs, without having to wait until spark discharge or partial discharge occurs. In addition, the position where the detection electrode 5 is attached is set to a position where the generated tear is reliably detected, so that it floats when the tear occurs, that is, a position close to the turning point of the stress cone. Is preferred.

[Brief description of the drawings]

FIG. 1 is a diagram showing an implementation state of an abnormality detection method according to an embodiment of the present invention.

FIG. 2 is a sectional view showing details of a terminal processing unit in FIG. 1;

FIG. 3 is a diagram showing a state in which a tear has occurred in the terminal processing unit 3 of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cable 3 ... Terminal processing part 4 ... Ground lead wire 5 ... Detection electrode 6 ... Abnormal diagnosis device 7,8 ... Probe 11 ... Cable conductor 12 ... Insulator 13 ... Semiconductive layer 14 ... Shield layer B 21 ... Stress cone 22: shield layer A 31, 33: wire 32, 34: soldered portion

Claims (2)

[Claims] 1. An abnormality detection method for detecting an abnormality occurring in a terminal processing unit of a CV cable having a shield layer covering an outer periphery of a stress cone, wherein the outer peripheral portion of the terminal processing unit is provided in a portion facing the shield layer. CV cable terminal processing, comprising: mounting an electrode, measuring a voltage induced at the electrode, and determining that a break has occurred in the cable shield layer of the terminal processing unit when a voltage is detected at the electrode. How to detect abnormalities in the part. 2. The CV cable according to claim 1, wherein the detection electrode is attached at a position facing the shield layer and at a position where the cable is reliably floated when a tear occurs in the cable shield layer of the terminal processing unit. An error detection method for the terminal processing unit.