JP2542406B2 - Insulation deterioration diagnosis method for power cables - Google Patents
Insulation deterioration diagnosis method for power cablesInfo
- Publication number
- JP2542406B2 JP2542406B2 JP62336141A JP33614187A JP2542406B2 JP 2542406 B2 JP2542406 B2 JP 2542406B2 JP 62336141 A JP62336141 A JP 62336141A JP 33614187 A JP33614187 A JP 33614187A JP 2542406 B2 JP2542406 B2 JP 2542406B2
- Authority
- JP
- Japan
- Prior art keywords
- power cable
- insulation deterioration
- component
- current
- leakage current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
- Testing Relating To Insulation (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明の活線状態にある電力ケーブルの絶縁劣化を診
断する電力ケーブルの絶縁劣化診断方法に関する。Description: TECHNICAL FIELD The present invention relates to a method for diagnosing insulation deterioration of a power cable in a live state of the present invention for diagnosing insulation deterioration of a power cable.
（従来の技術） CVケーブル等の電力ケーブルの絶縁劣化の主要な原因
に水トリー劣化がある。水トリーは絶縁体中に発生した
ツリー状の水のパスをいい、水トリーが大きくなるとこ
の水のパスを通して電流が流れ絶縁破壊が発生する。従
来、第３図に示すように、活線状態の下で電力ケーブル
１の金属しゃへい層（シース）２からの漏れ電流の直流
成分の大きさを測定して電力ケーブルの水トリー劣化を
診断することが行われている。金属しゃへい層２と大地
との間に挿入接続された検出インピーダンス７はコンデ
ンサ等から成り、商用周波数以上の周波数の電圧に対し
てはアース状態にあるが直流電圧に対しては所定のイン
ピーダンスを与える。符号５は電力ケーブル１に接続さ
れた変圧器の二次側コイルを示す。金属しゃへい層２か
らの漏れ電流による直流電圧成分が電圧計８により測定
され、その大きさから電力ケーブルの絶縁劣化が診断さ
れる。(Prior Art) Water tree deterioration is a major cause of insulation deterioration of power cables such as CV cables. The water tree is a tree-shaped water path generated in the insulator. When the water tree becomes large, a current flows through this water path to cause dielectric breakdown. Conventionally, as shown in FIG. 3, the magnitude of the DC component of the leakage current from the metal shielding layer (sheath) 2 of the power cable 1 is measured under a live condition to diagnose the water tree deterioration of the power cable. Is being done. The detection impedance 7 inserted and connected between the metal shield layer 2 and the ground is composed of a capacitor or the like, and is in a ground state for a voltage of a frequency higher than the commercial frequency, but gives a predetermined impedance for a DC voltage. . Reference numeral 5 indicates a secondary coil of the transformer connected to the power cable 1. The DC voltage component due to the leakage current from the metal shield layer 2 is measured by the voltmeter 8, and the insulation deterioration of the power cable is diagnosed based on the measured value.
（発明が解決しようとする問題点） しかしながら、従来の漏れ電流の直流成分を測定し絶
縁劣化を診断する方法では、地中に還流している直流迷
走電流、異種金属の接触により生ずる電池作用等による
大地電位等の絶縁劣化とは無関係のものが漏れ電流によ
る直流成分に重畳し、絶縁劣化の診断を誤るという問題
点がある。(Problems to be solved by the invention) However, in the conventional method of measuring the DC component of the leakage current and diagnosing the insulation deterioration, the DC stray current circulating in the ground, the battery action caused by the contact of different metals, etc. However, there is a problem in that something unrelated to the insulation deterioration such as the ground potential due to is superimposed on the DC component due to the leakage current, resulting in an incorrect diagnosis of the insulation deterioration.
本発明は、上記事情に鑑みてなされたものであり、直
流迷走電流や金属しゃへい上に生じた電位の影響を排除
して、電力ケーブルの絶縁劣化を診断できる電力ケーブ
ルの絶縁劣化診断方法を提供することを目的とする。The present invention has been made in view of the above circumstances, and provides a method for diagnosing insulation deterioration of a power cable by eliminating the influence of a DC stray current or the potential generated on a metal shield, and diagnosing the insulation deterioration of the power cable. The purpose is to do.
（問題点を解決するための手段） 上記目的を達成するために、本発明によれば、活線状
態下の電力ケーブルからの漏れ電流の中から高調波成分
を測定することにより電力ケーブルの絶縁体中に水トリ
ーが発生していることを検知し、前記電力ケーブルの絶
縁劣化を診断する電力ケーブルの絶縁劣化診断方法が提
供される。(Means for Solving the Problems) In order to achieve the above object, according to the present invention, insulation of a power cable is obtained by measuring a harmonic component from leakage current from the power cable under a live condition. There is provided a method for diagnosing insulation deterioration of a power cable, which detects the occurrence of a water tree in the body and diagnoses the insulation deterioration of the power cable.
（作用） 活線状態にある電力ケーブルの金属しゃへい層からの
漏れ電流を周波数分析して高調波成分を測定し、高周波
成分の有無により電力ケーブルの水トリーによる絶縁劣
化を診断する。(Function) The leakage current from the metal shield layer of the power cable in a live state is frequency-analyzed to measure the harmonic component, and the insulation deterioration due to the water tree of the power cable is diagnosed by the presence or absence of the high-frequency component.
（実施例） 以下、本発明の実施例を添付図面に基づいて詳細に説
明する。(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.
第１図は本発明を実施するための測定装置を示し、検
出インピーダンス３及び微小電圧計４を除いた、他のも
のは第３図の従来の測定装置における同一符号のものと
変りがない。電力ケーブル１の金属しゃへい層２と大地
間に挿入接続された検出インピーダンス３は、50Hz又は
60Hzの商用周波数以下の周波数成分に対しては十分に小
さい値となるが、高周波成分に対しては所定の大きさの
インピーダンス値を示す高域濾波器の特性を有してい
る。従って、漏れ電流の直流成分や基本波成分は、誤差
の原因であった直流迷走電流等と共に検出インピーダン
ス３を通してアースに流れる。微小電圧計４は検出イン
ピーダンス３の両端の電圧信号波形を周波数分析するス
ペクトラムアナライザの機能を有し、各周波数成分につ
いて微小電圧を測定できる。FIG. 1 shows a measuring device for carrying out the present invention, and the other components except the detection impedance 3 and the micro voltmeter 4 are the same as those in the conventional measuring device shown in FIG. The detection impedance 3 inserted and connected between the metal shield layer 2 of the power cable 1 and the ground is 50 Hz or
Although it has a sufficiently small value for frequency components below the commercial frequency of 60 Hz, it has the characteristics of a high-pass filter showing an impedance value of a predetermined magnitude for high frequency components. Therefore, the direct current component and the fundamental wave component of the leakage current flow to the ground through the detection impedance 3 together with the direct current stray current that caused the error. The micro voltmeter 4 has the function of a spectrum analyzer that frequency-analyzes the voltage signal waveform across the detection impedance 3 and can measure a micro voltage for each frequency component.
水トリーはその先端がとがっており、一方向からの電
流は通しやすいが他方向からの電流は通しにくいという
整流作用を有した非対称電極となる。電力ケーブル１の
絶縁体からの漏れ電流は水トリー等の非対称電極を経由
すると、商用周波数の場合にはどちらかの極性の電流が
流れにくくなるので第２図に曲線６で示すような半波整
流電流波形ｉになっている。この半波整流波形は、電気
鉄道に基づく直流迷走電流や極部電池による大地電位に
基づく直流電流が単なる直流電流であることと比べると
大きな違いである。この半波整流電流波形ｉがどのよう
な周波数成分を含んでいるかみるために、フーリエ級数
で表現すると次の（１）式のようになる。The water tree has a sharp tip and serves as an asymmetric electrode having a rectifying action that current from one direction is easily passed but current from the other direction is hard to pass. If the leakage current from the insulator of the power cable 1 passes through an asymmetrical electrode such as a water tree, it becomes difficult for the current of either polarity to flow at the commercial frequency. It has a rectified current waveform i. This half-wave rectified waveform is a big difference as compared with the fact that the DC stray current based on the electric railway and the DC current based on the ground potential due to the battery of the poles are mere DC currents. In order to see what frequency component this half-wave rectified current waveform i contains, it is expressed by the following formula (1) when expressed by a Fourier series.
（１）から半波整流電流波形ｉは、直流成分の大きさ
が0.318、第２高調波成分の大きさが0.212、第４高調波
成分の大きさが0.0424,……というように偶数高調波成
分を持っていることがわかる。中でも第２高調波成分が
一番大きいこともわかる。従って、第１図に示す微小電
圧計４で電力ケーブル１からの漏れ電流のうちで基本周
波数の高調波成分の大きさを測定すれば、直流迷走電流
等に影響されずに電力ケーブル１からの漏れ電流のみを
知ることができ、電力ケーブルの絶縁劣化の度合を診断
することができる。 From (1), the half-wave rectified current waveform i shows that the magnitude of the DC component is 0.318, the magnitude of the second harmonic component is 0.212, the magnitude of the fourth harmonic component is 0.0424, and so on. You can see that it has ingredients. It can also be seen that the second harmonic component is the largest among them. Therefore, if the magnitude of the harmonic component of the fundamental frequency in the leakage current from the power cable 1 is measured with the micro voltmeter 4 shown in FIG. Only the leakage current can be known, and the degree of insulation deterioration of the power cable can be diagnosed.
次に、本発明の電力ケーブルの絶縁劣化診断方法によ
り実際に測定した具体例について説明する。Next, a specific example actually measured by the insulation cable deterioration diagnosis method of the present invention will be described.
水トリーの発生している6kv架橋ポリエチレン絶縁ケ
ーブルと、新品で水トリーの発生していない6kv架橋ポ
リエチレン絶縁ケーブルとを用意し、第１図に示す測定
装置によって各三相絶縁ケーブルの各相からの漏れ電流
の第２高調波成分を測定した。測定結果は表１に示すよ
うであった。Prepare a 6kv cross-linked polyethylene insulated cable with water tree and a new 6kv cross-linked polyethylene insulated cable with no water tree, and measure each phase of each three-phase insulated cable with the measuring device shown in Fig. 1. The second harmonic component of the leakage current was measured. The measurement results are shown in Table 1.
大きさPiは観測した半波整流電流波形のフーリエ変換
した値から求める。つまり、大きさPiは各周波数成分の
大きさ（振幅）uiの絶縁値を基本波成分の大きさu1の絶
対値で基準化して求める。 The size P i is obtained from the Fourier-transformed value of the observed half-wave rectified current waveform. That is, the magnitude P i is obtained by normalizing the insulation value of the magnitude (amplitude) u i of each frequency component with the absolute value of the magnitude u 1 of the fundamental wave component.
ここで、u0は直流成分、そして、u2は第２高調波成分
である。検出インピーダンス３を通して直流成分及び基
本波成分を大地に流しても実際には微小電圧計４によっ
て漏れ電流の基本成分が最も大きく測定されるために、
各周波成分の大きさを基本波成分で規準化したものであ
る。表１からわかるように、水トリーが発生していない
供試ケーブルの赤相では第２高調波成分が5.1×10-6の
大きさであって無いに等しいのに対し、水トリーが発生
している供試ケーブルの赤相では第２高調波成分が2.5
×10-3の大きさであり、水トリーが発生していない供試
ケーブルに比べて３桁大きいことがわかる。他相につい
ても同様である。従って、本発明の電力ケーブルの絶縁
劣化診断方法によって電力ケーブルの絶縁劣化の診断が
可能であることがわかる。 Here, u 0 is a DC component, and u 2 is a second harmonic component. Since the basic component of the leakage current is actually measured by the minute voltmeter 4 even if the direct current component and the fundamental wave component are flown to the ground through the detection impedance 3,
The magnitude of each frequency component is normalized by the fundamental wave component. As can be seen from Table 1, in the red phase of the test cable in which no water tree is generated, the second harmonic component is not equal to 5.1 × 10 -6 , which is equivalent to that of the water tree. The second harmonic component is 2.5 in the red phase of the tested cable
The size is × 10 -3 , which is three orders of magnitude larger than that of the test cable in which no water tree is generated. The same applies to the other phases. Therefore, it can be understood that the insulation deterioration diagnosis method of the power cable of the present invention can diagnose the insulation deterioration of the power cable.
（発明の効果） 以上説明したように、本発明によれば、活線状態下の
電力ケーブルからの漏れ電流の中から高調波成分を測定
することにより電力ケーブルの絶縁体中に水トリーが発
生していることを検知し、前記電力ケーブルの絶縁劣化
を診断することにより、絶縁劣化の診断において誤差の
原因となる直流迷走電流や大地電位の影響を排除した精
度の良い絶縁劣化の診断が実現でき、その結果運転中に
発生する絶縁破壊事故を未然に防止することができると
いう効果が得られる。(Effects of the Invention) As described above, according to the present invention, a water tree is generated in an insulator of a power cable by measuring a harmonic component in a leakage current from the power cable under a live state. It is possible to realize accurate diagnosis of insulation deterioration by eliminating the effects of DC stray current and ground potential that cause errors in insulation deterioration diagnosis by detecting that As a result, it is possible to prevent the dielectric breakdown accident that occurs during operation from occurring.
第１図は本発明を実施するための測定装置を示すブロッ
ク図、第２図は活線状態にある電力ケーブルから発生し
非対称電極を経由して測定された漏れ電流の波形を示す
図、第３図は従来の漏れ電流の直流成分を測定する測定
装置を示すブロックである。 １……電力ケーブル、２……金属しゃへい層、3,7……
検出インピーダンス、４……微小電圧計、５……変圧器
の二次側コイル、８……電圧計。FIG. 1 is a block diagram showing a measuring device for carrying out the present invention, and FIG. 2 is a diagram showing a waveform of a leakage current generated from a power cable in a live state and measured through an asymmetric electrode, FIG. 3 is a block diagram showing a conventional measuring device for measuring the DC component of the leakage current. 1 ... Power cable, 2 ... Metal shield layer, 3, 7 ...
Detection impedance, 4 ... Micro voltmeter, 5 ... Transformer secondary coil, 8 ... Voltmeter.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 岩崎 邦男 東京都品川区東品川４―13―14 古河電 気工業株式会社品川事業所内 (56)参考文献 特開 昭59−202077（ＪＰ，Ａ) 特開 昭60−216273（ＪＰ，Ａ) 「高電圧試験ハンドブック」Ｐ．１, ＰＰ．10−11，Ｐ．353，ＰＰ．386− 392電気学会昭58−３−30発行 速水俊幸「ＣＶケーブル」ＰＰ．204 −206コロナ社昭61−９−30発行 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Iwasaki 4-13-14 Higashi-Shinagawa, Shinagawa-ku, Tokyo Inside Furukawa Electric Co., Ltd. (56) Reference JP-A-59-202077 (JP, A) JP-A-60-216273 (JP, A) "High voltage test handbook" P. 1, PP. 10-11, p. 353, PP. 386-392 Published by The Institute of Electrical Engineers of Japan Sho 58-3-30 Toshiyuki Hayami "CV Cable" PP. Issued 204-206 Corona Publishing Company Sho 61-9-30
Claims (1)
の中から高調波成分を測定することにより電力ケーブル
の絶縁体中に水トリーが発生していることを検知し、前
記電力ケーブルの絶縁劣化を診断することを特徴とする
電力ケーブルの絶縁劣化診断方法。1. A method for detecting a water tree in an insulator of a power cable by measuring a harmonic component in a leakage current from the power cable under a live line condition, A method for diagnosing insulation deterioration of a power cable, which comprises diagnosing insulation deterioration.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62336141A JP2542406B2 (en) | 1987-12-29 | 1987-12-29 | Insulation deterioration diagnosis method for power cables |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62336141A JP2542406B2 (en) | 1987-12-29 | 1987-12-29 | Insulation deterioration diagnosis method for power cables |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01174988A JPH01174988A (en) | 1989-07-11 |
| JP2542406B2 true JP2542406B2 (en) | 1996-10-09 |
Family
ID=18296116
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62336141A Expired - Fee Related JP2542406B2 (en) | 1987-12-29 | 1987-12-29 | Insulation deterioration diagnosis method for power cables |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2542406B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6340891B1 (en) * | 1998-04-14 | 2002-01-22 | Furukawa Electric Co., Ltd. | Method of diagnosing deterioration of the insulation of an electric power cable |
| JP3693149B2 (en) | 1999-01-11 | 2005-09-07 | 住友電装株式会社 | connector |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59202077A (en) * | 1983-04-30 | 1984-11-15 | Hitachi Cable Ltd | Diagnosis of insulation deterioration of power cable |
| JPS60216273A (en) * | 1984-04-12 | 1985-10-29 | Hitachi Cable Ltd | Detection of sheath damage of power cable under live condition |
-
1987
- 1987-12-29 JP JP62336141A patent/JP2542406B2/en not_active Expired - Fee Related
Non-Patent Citations (2)
| Title |
|---|
| 「高電圧試験ハンドブック」Ｐ．１，ＰＰ．１０−１１，Ｐ．３５３，ＰＰ．３８６−３９２電気学会昭５８−３−３０発行 |
| 速水俊幸「ＣＶケーブル」ＰＰ．２０４−２０６コロナ社昭６１−９−３０発行 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01174988A (en) | 1989-07-11 |
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