JPS62232579A - Method for detecting accident point of power cable - Google Patents

Abstract

PURPOSE:To enhance the detection accuracy of an accident point, by performing the detection of the accidental point using the resistance based on the insulating breakdown at the accidental point of the insulating film layer between two shielding layers. CONSTITUTION:It is assumed that a line accident is generated at the point X of a trouble cable 1A and insulating breakdown is generated in an insulator 4 and an insulating film layer 7 at the point X. In this case, at the terminals d1, d2 of cables 1A, 1B, short-circuit connection is respectively generated between the conductors 2A, 2B of both cables, between the shielding layers 6A, 6B thereof and between the shielding layers 8A, 8B. A series circuit of resistors Ra, Rb and a meter G are respectively connected between the base terminals C1, C2 of the shielding layers 6A, 6B in parallel and a series circuit of a resistor Rc and a DC power source E is connected between the connection point of the resistances Ra, Rb and earth. Herein, if the resistor Rb is made variable to take equilibrium, when the distance from the base terminal to the point X is set to (x) and the total length of each cable is set to L, (x) is calculated from formula I. At this time, the detection of the point X is performed using the resistance generated at the point X by insulating breakdown.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、電力ケーブルの事故点を検出する電力り°−
プルの事故点検出方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method for detecting fault points in power cables.
The present invention relates to a method for detecting a pull accident point.

（従来技術） 電力ケーブルは、事故が発生ずると、導体と遮蔽層間の
絶縁体がぞの事故点で絶縁破壊され、成る抵抗値をもっ
て導体と遮＃１ｔｒ４問が短絡され、導体がその事故点
で接地された状態になる。このような事故点の検出を、
従来は抵抗ブリッジ回路を利用したマーレーループ法等
を用いて行っていた。(Prior art) When an accident occurs in a power cable, the insulator between the conductor and the shielding layer breaks down at the fault point, the conductor and the shield #1tr4 are short-circuited with the resulting resistance value, and the conductor is connected to the fault point. becomes grounded. Detection of such accident points,
Conventionally, this has been done using a Murray loop method using a resistor bridge circuit.

（発明が解決しようとする問題点） しかしながら、絶縁体はその肉厚が大きいので、事故時
における絶縁破壊の状況がその都度大きく異なり、その
結果、事故点における導体と遮蔽層間の抵抗値も事故の
状況に応じて数１０ＭΩ〜数ＫＯと大きく変化し、しか
も抵抗値が不安定のため、事故点の検出が困難となる問
題点があった。(Problem to be solved by the invention) However, since the thickness of the insulator is large, the situation of dielectric breakdown at the time of an accident differs greatly each time, and as a result, the resistance value between the conductor and the shielding layer at the point of the accident also changes. The resistance value varies greatly from several tens of MΩ to several KO depending on the situation, and the resistance value is unstable, making it difficult to detect the point of failure.

本発明の目的は、事故点の抵抗値を小さくでき、しかも
その抵抗値が従来のように事故の状況に応じて大ぎく変
化することがないようにして事故点の検出を粘度よく行
うことができる電力ケーブルの事故点検出方法を提供す
ることにある。An object of the present invention is to reduce the resistance value of the accident point, and to detect the accident point with good viscosity by preventing the resistance value from changing significantly depending on the accident situation as in the past. An object of the present invention is to provide a method for detecting a fault point in a power cable.

（問題点を解決するだめの手段） 上記の目的を達成するための本発明の手段を、実施例に
対応する第１図及び第２図を参照して説明すると、本発
明は化カケープル１に第１．第２の遮蔽層６．８を絶縁
薄膜層７を介して相互に接近させて設け、事故発生時に
おける事故点Ｘでの前記第１．第２の遮蔽層６．８間で
の前記絶縁薄膜層７の絶縁破壊にもとずく抵抗Ｒ７を利
用して該事故点Ｘの検出を行うことを特徴とする。(Means for Solving the Problems) The means of the present invention for achieving the above object will be explained with reference to FIGS. 1 and 2, which correspond to embodiments. 1st. The second shielding layers 6.8 are provided close to each other via the insulating thin film layer 7, and the first shielding layers 6.8 are provided at the accident point X when an accident occurs. It is characterized in that the fault point X is detected using the resistance R7 based on the dielectric breakdown of the insulating thin film layer 7 between the second shielding layers 6 and 8.

（作用） このように第１．第２の遮蔽ｌｌ！ｉ６．８問における
絶縁層１１！１１７の事故点Ｘでの抵抗Ｒ７を利用して
事故点Ｘの検出を行うと、第１．第２の遮蔽層６．８ｎ
の絶縁ＦＥＷ膜層７は導体２と第１の遮蔽層６ｆ２１］
の絶縁体４に比べて著しく薄いので、抵抗値も小さくな
り、事故点Ｘの検出精度を上げることができる。(Effect) In this way, the first. Second shield! When the fault point X is detected using the resistance R7 of the insulating layer 11!117 at the fault point X in question i6.8, the first. Second shielding layer 6.8n
The insulating FEW film layer 7 includes the conductor 2 and the first shielding layer 6f21]
Since it is significantly thinner than the insulator 4, the resistance value is also reduced, and the detection accuracy of the fault point X can be improved.

（実施例） 以下本発明の実施例を図面を参照して詳細に説明する。(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

本発明では、事故点の検出精度を上げるため、絶縁体の
外周に第１．第２の遮蔽層を設けた化カケープルを用い
る。その−例を第１図にて説明する。この化カケープル
１は、導体２の外周に内部半導１ｉ層３．絶縁体４．外
部半′Ｓ電層５゜第１の遮蔽層６．絶縁薄膜層７．第２
の遮蔽Ｈ８゜外部絶縁層９．保護シース１０が順次同軸
状に設けられた構造になっている。絶縁層膜層７は、例
えば第１の遮蔽層６又は第２の遮蔽層８のラミネートテ
ープ層として薄り（例えば、ポリエチレンの場合で一例
を示すと１００〜５００μｍ程度）形成する。In the present invention, in order to increase the accuracy of detecting the fault point, a first insulator is placed on the outer periphery of the insulator. A chemical caple provided with a second shielding layer is used. An example thereof will be explained with reference to FIG. This chemical capeple 1 has an internal semiconductor layer 3 on the outer circumference of the conductor 2. Insulator 4. External semi-electrical layer 5. First shielding layer 6. Insulating thin film layer7. Second
Shielding H8° external insulating layer 9. It has a structure in which protective sheaths 10 are sequentially provided coaxially. The insulating layer 7 is formed as a laminate tape layer of the first shielding layer 6 or the second shielding layer 8 to be thin (for example, about 100 to 500 μm in the case of polyethylene).

このような化カケープル１の使用中に、成る点Ｘで線絡
事故が発生した場合に、事故点Ｘの検出をマーレールー
プ法で行う場合の例について第２図を参照して説明する
。図において、１Ａは事故ケーブル、１Ｂは健全ケーブ
ル、２Ａは事故ケーブル１Ａの導体、２Ｂは健全ケーブ
ル１Ｂの導体、６Ａは事故ケーブル１Ａの第１の遮蔽層
、６Ｂは健全タープル１Ｂの第１の遮蔽層、８Ａは事故
ケーブル１Ａの第２のｍ１層、８Ｂは健全ケーブル１Ｂ
の第２の遮蔽層である。An example of detecting the fault point X using the Murray loop method when a wire shorting fault occurs at a point X during use of such a capacitor 1 will be described with reference to FIG. In the figure, 1A is the accident cable, 1B is the sound cable, 2A is the conductor of the accident cable 1A, 2B is the conductor of the sound cable 1B, 6A is the first shielding layer of the accident cable 1A, and 6B is the first shield layer of the sound cable 1B. Shielding layer, 8A is the second m1 layer of accident cable 1A, 8B is healthy cable 1B
is the second shielding layer.

事故ケーブル１Ａは、事故点Ｘで線絡事故が発生し、そ
の事故点Ｘで絶縁体４及び絶縁薄ＷＡ層７が絶縁破壊し
たとする。この場合、両ケーブル１Ａ、ＩＢの末端ｄｉ
、ｄ２で両ケーブル１Ａ、１Ｂの導体２Ａ、２Ｂの相互
間、第１の遮蔽層６Ａ。It is assumed that in the accident cable 1A, a wire shorting accident occurs at the accident point X, and the insulator 4 and the thin insulating WA layer 7 break down at the accident point X. In this case, the terminal di of both cables 1A and IB
, d2 between the conductors 2A and 2B of both cables 1A and 1B, and the first shielding layer 6A.

６Ｂの相互間、第２の遮蔽１１８Ａ、８Ｂ＋７）相互間
をそれぞれ短絡接続する。また、これら第１の遮蔽ｆ１
６Ａ、６Ｂの基端ｃｉ、ｃ２間には抵抗Ｒａ。6B and the second shields 118A and 8B+7) are short-circuited. In addition, these first shields f1
There is a resistance Ra between the base ends ci and c2 of 6A and 6B.

Ｒｂの直列回路とメータＧとをそれぞれ並列接続し、抵
抗Ｒａ、　Ｒｂの相互の接続点とアース間には抵抗Ｒｃ
と直流１１Ｅとの直列回路を接続する。The series circuit of Rb and the meter G are connected in parallel, and a resistor Rc is connected between the mutual connection point of resistors Ra and Rb and the ground.
Connect a series circuit of 11E and DC 11E.

このとき直流電源Ｅのアースは、第２の遮蔽層８Ａとア
ース結合する。なお、Ｒ４は事故点Ｘでの絶縁体４の絶
縁破壊により形成された抵抗、Ｒ７は事故点Ｘでの絶縁
薄膜層７の絶縁破壊により形成された抵抗、χは基端か
ら事故点Ｘまでの距離、ＬはケーブルＩＡ、ＩＢの各仝
艮である。At this time, the ground of the DC power supply E is coupled to the second shielding layer 8A. In addition, R4 is the resistance formed by the dielectric breakdown of the insulator 4 at the fault point X, R7 is the resistance formed by the dielectric breakdown of the insulating thin film layer 7 at the fault point X, and χ is the resistance from the base end to the fault point X. , and L is the distance between cables IA and IB.

図示の状態で、抵抗Ｒｂを「程度することによりＲａ／
Ｒａを調整して平衡をとると、 ｌ’？　ａ　／　ｌ−＜　ｂ　＝　（２Ｌ−χ）／χＺ
＝２・Ｒｂ−１／（Ｒａ＋Ｒｂ） より事故点Ｘまでの距離χを求めることができる。In the illustrated state, by adjusting the resistance Rb to
If we adjust Ra to achieve equilibrium, l'? a/l−<b=(2L−χ)/χZ
=2.Rb-1/(Ra+Rb) The distance χ to the accident point X can be found.

この場合、事故点Ｘでの抵抗として、事故ケーブル１Ａ
の事故点Ｘでの絶縁層膜層７の絶縁破壊による抵抗１＜
７を利用しでいるので、従来のような導体２Δと第１の
遮蔽層６Ａ間の絶縁体４の絶縁破壊による抵抗Ｒ４に比
べて抵抗値が著しく小さくなり、また抵抗値のバラツキ
も小さくなり、精度よく事故点Ｘの検出を行うことがで
きる。In this case, as the resistance at the fault point X, the fault cable 1A
Resistance 1< due to dielectric breakdown of the insulating layer film layer 7 at the accident point X
7, the resistance value is significantly smaller than the conventional resistance R4 due to dielectric breakdown of the insulator 4 between the conductor 2Δ and the first shielding layer 6A, and the variation in resistance value is also reduced. , the accident point X can be detected with high accuracy.

なお、本発明はマーレーループ法以外の公知の方法によ
って事故点Ｘの検出を（ｊう方法にも同様に適用できる
ことは勿論である （発明の効果） 以上説明したように本発明では、第１．第２の遮蔽層間
における絶縁薄膜層の絶縁破壊による抵抗値を利用して
事故点の検出を行うので、この抵抗値は絶縁＾や膜層が
導体の外周を覆う絶縁体より薄いため、絶縁体の絶縁破
壊による抵抗値に比べて著しく小さくなり、また抵抗値
のバラツキも小さくなり、事故点の検出ｆａ　１．ｔＺ
を上げることができる。更に、本発明では、遮蔽層を利
用して測定を行うので、その抵抗値は導体を利用して測
定を行う場合の導体の抵抗値より高くなり、従ってこの
面でも距離測定精度を向上さけることができる。It goes without saying that the present invention can be similarly applied to a method of detecting the accident point X using a known method other than the Murray loop method (effects of the invention). ．Since the fault point is detected by using the resistance value due to dielectric breakdown of the insulating thin film layer between the second shielding layers, this resistance value is thinner than the insulation^ or the insulator covering the outer periphery of the conductor, so this resistance value is The resistance value is significantly smaller than the resistance value due to dielectric breakdown of the body, and the variation in resistance value is also small, making it possible to detect the fault point fa 1.tZ
can be raised. Furthermore, in the present invention, since measurement is performed using a shielding layer, its resistance value is higher than the resistance value of a conductor when measurement is performed using a conductor. Therefore, it is also possible to improve distance measurement accuracy in this aspect. I can do it.

かつまた、事故点の抵抗値が高くて焼成の必要があると
ぎには、絶縁薄膜層なので焼成エネルギーが少なくてす
む利点がある。Moreover, when the resistance value at the fault point is high and firing is necessary, the insulating thin film layer has the advantage that less firing energy is required.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明で使用する電力ケーブルの一例を示す横
断面図、第２図は本発明の方法の実施状態を示１説明図
である。 １・・・電力ケーブル、２・・・導体、４・・・絶縁体
、６・・・第１の遮蔽層、７・・・絶縁源ＩＩ０層、８
・・・第２の遮蔽層。 第１　図 第２　図FIG. 1 is a cross-sectional view showing an example of a power cable used in the present invention, and FIG. 2 is an explanatory diagram showing a state in which the method of the present invention is implemented. DESCRIPTION OF SYMBOLS 1... Power cable, 2... Conductor, 4... Insulator, 6... First shielding layer, 7... Insulation source II0 layer, 8
...Second shielding layer. Figure 1 Figure 2

Claims (1)

【特許請求の範囲】[Claims] 電力ケーブルに第１、第２の遮蔽層を絶縁薄膜層を介し
て相互に接近させて設け、事故発生時における事故点で
の前記第１、第２の遮蔽層間での前記絶縁薄膜層の絶縁
破壊にもとずく抵抗を利用して該事故点の検出を行うこ
とを特徴とする電力ケーブルの事故点検出方法。A power cable is provided with first and second shielding layers close to each other via an insulating thin film layer, and the insulating thin film layer is insulated between the first and second shielding layers at the accident point when an accident occurs. A method for detecting a fault point in a power cable, characterized in that the fault point is detected using resistance based on destruction.