JPH0486571A - Measurement of insulation resistance for cable sheath under hot line - Google Patents
Measurement of insulation resistance for cable sheath under hot lineInfo
- Publication number
- JPH0486571A JPH0486571A JP20203690A JP20203690A JPH0486571A JP H0486571 A JPH0486571 A JP H0486571A JP 20203690 A JP20203690 A JP 20203690A JP 20203690 A JP20203690 A JP 20203690A JP H0486571 A JPH0486571 A JP H0486571A
- Authority
- JP
- Japan
- Prior art keywords
- resistance
- resistance value
- cable
- sheath
- impedance
- 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.)
- Granted
Links
- 238000009413 insulation Methods 0.000 title claims description 16
- 238000005259 measurement Methods 0.000 title claims description 9
- 238000001514 detection method Methods 0.000 claims abstract description 23
- 238000000034 method Methods 0.000 claims description 11
- 230000006866 deterioration Effects 0.000 description 19
- 238000003745 diagnosis Methods 0.000 description 10
- 239000012212 insulator Substances 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 239000004020 conductor Substances 0.000 description 3
- 235000006650 Syzygium cordatum Nutrition 0.000 description 2
- 240000005572 Syzygium cordatum Species 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Testing Relating To Insulation (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、活線状態にあるケーブルのシースの絶縁抵抗
を測定するための方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for measuring the insulation resistance of a cable sheath in a live condition.
し従来技術及び解決しようとする課題］近年、ケーブル
絶縁体の劣化度合を活線下において♂す定する手段とし
て、ケーブル遮蔽層と大地との間を接続する接地線中を
流れる電流成分を解析して劣化診断を行う方法か有望視
されている。[Prior art and problems to be solved] In recent years, as a means of determining the degree of deterioration of cable insulators under live wires, analysis of the current component flowing in the grounding wire that connects the cable shielding layer and the earth has been developed. This method is considered promising for deterioration diagnosis.
例えばＣＶケーブル絶縁体中に水トリー劣化部か存在す
る場合、この水トリー劣化度合に応じた大とざて概ね数
Ｈｚ以下を主成分とする脈動電流成分が接地線中に発生
するという知見に基づいて、接地線中間部にインピーダ
ンスを強制的に挿入して接地線電流を検出し、ローパス
フィルタ等を使用して前記脈動電流成分を計測すること
により劣化診断を行う手段か提案されている。For example, it is known that if there is a water-tree deteriorated part in the CV cable insulation, a pulsating current component whose main component is approximately several Hz or less is generated in the ground wire depending on the degree of water-tree deterioration. Based on this, a method has been proposed in which deterioration diagnosis is performed by forcibly inserting an impedance into the middle part of the grounding line to detect the grounding line current and measuring the pulsating current component using a low-pass filter or the like.
上記のようなケーブル絶縁体の劣化診断を行うに際して
は、ケーブル遮蔽層か接地線以外の他の導体で接地され
ていないこと、換言するとケーブルシースの絶縁抵抗か
正常であることか、正確な劣化診断を行う上で重要とな
る。すなわち、該劣化診断は接地線電流を利用して行う
ものであるので、遮蔽層の絶縁状態が悪化していると本
来接地線中を流れるべき電流が全て接地線中を流れなく
なり、測定値の信頼性が著しく低下するからである。When diagnosing the deterioration of cable insulation as described above, it is important to check that the cable is not grounded with any other conductor other than the cable shielding layer or the grounding wire, in other words, that the insulation resistance of the cable sheath is normal, and to determine the exact deterioration. This is important in making a diagnosis. In other words, since the deterioration diagnosis is performed using the grounding wire current, if the insulation condition of the shielding layer deteriorates, all the current that should normally flow through the grounding wire will no longer flow through the grounding wire, and the measured value will change. This is because reliability is significantly reduced.
従ってケーブルシースの絶縁抵抗を測定することは意義
あることであるが、従来活線状態にあるケーブルのシー
ス抵抗を測定する有効な手段は提案されていない。また
、ケーブル絶縁体の劣化診断を行うに際し、ケーブルシ
ース抵抗を事前に測定することの有用性か充分認識され
ていないのが現状である。Therefore, it is significant to measure the insulation resistance of a cable sheath, but no effective means for measuring the sheath resistance of a live cable has been proposed. Furthermore, when diagnosing the deterioration of cable insulators, the usefulness of measuring cable sheath resistance in advance is currently not fully recognized.
従って本発明は、接地線電流を解析してケーブル絶縁体
の劣化診断を行うに際して特に有用な、ケーブルシース
の絶縁抵抗♂り定力法を提供することを目的とする。Accordingly, an object of the present invention is to provide a constant force method based on the insulation resistance of a cable sheath, which is particularly useful when diagnosing deterioration of a cable insulator by analyzing ground wire current.
［課題を解決するための手段］
本発明の活線下ケープ、ルシースの絶縁抵抗測定方法は
、ケーブル遮蔽層の接地線に既知の抵抗値の検出インピ
ーダンスが挿入されてなるケーブル線路において、該検
出インピーダンスの両端において測定器で抵抗値を測定
し、前記検出インピーダンスの抵抗値と、測定器により
実？！Ｉされた測定抵抗値とからケーブルシースの抵抗
値を算出することを特徴とするものである。[Means for Solving the Problems] The method for measuring insulation resistance of the live line cape and Lucis of the present invention is to detect the detection impedance in a cable line in which a detection impedance with a known resistance value is inserted into the ground wire of the cable shielding layer. Measure the resistance value with a measuring device at both ends of the impedance, and measure the resistance value of the detected impedance and the actual resistance value with the measuring device. ! This method is characterized in that the resistance value of the cable sheath is calculated from the measured resistance value.
［作用コ
上記構成において、ケーブル遮蔽層−大地間の閉ループ
を等価的に考慮すると、検出インピーダンスとシース絶
縁抵抗とが並列に接続されていることとなる。従って、
接地線に実装された状態の前記検出インピーダンスの両
端において測定した測定抵抗値は、検出インピーダンス
とシース抵抗との並列接続抵抗を合成測定した値となる
。而して、検出インピーダンス単体の抵抗値か既知であ
れば、上記測定抵抗値と既知抵抗値とから未知のケーブ
ルシース絶縁抵抗値を算出することができる。[Operation] In the above configuration, if the closed loop between the cable shielding layer and the ground is equivalently considered, the detection impedance and the sheath insulation resistance are connected in parallel. Therefore,
The measured resistance value measured at both ends of the detection impedance mounted on the ground wire is a combined value of the parallel connection resistance of the detection impedance and the sheath resistance. Thus, if the resistance value of the detection impedance alone is known, the unknown cable sheath insulation resistance value can be calculated from the measured resistance value and the known resistance value.
［実施例コ
以下図面に基づいて本発明の一実施例を詳細に説明する
。[Embodiment] An embodiment of the present invention will be described in detail below based on the drawings.
第１図は本発明にかかる測定方法を示す回路図であり、
第２図は第１図の等価回路図である。第１図において、
１はＣ■ケーブルであり、１０はその導体、１１は架橋
ポリエチレン絶縁体、１２は遮蔽層、１３はケーブルシ
ースをそれぞれボしている。導体１０には交流電源Ｅに
より交流電圧か印加されており、ケーブル１は活線状態
とされている。なお、Ｒｓはケーブルシース１３の絶縁
抵抗、Ｃｓは遮蔽層−大地間の静電容量をそれぞれ示し
ている。遮蔽層１２からは接地線２か引と出されて接地
されており、接地線２の中間部には検出インピーダンス
３が挿入されている。そして、検出インピーダンス３の
遮蔽層１２側接続端Ａと大地側接続端Ｂとにテスター等
の測定器４の測定端を接続し、検出インピーダンス３の
両端における抵抗値を測定できるよう構成している。FIG. 1 is a circuit diagram showing the measurement method according to the present invention,
FIG. 2 is an equivalent circuit diagram of FIG. 1. In Figure 1,
1 is a C■ cable, 10 is its conductor, 11 is a crosslinked polyethylene insulator, 12 is a shielding layer, and 13 is a cable sheath. An AC voltage is applied to the conductor 10 by an AC power source E, and the cable 1 is in a live state. Note that Rs represents the insulation resistance of the cable sheath 13, and Cs represents the capacitance between the shielding layer and the ground. A grounding wire 2 is drawn out from the shielding layer 12 and is grounded, and a detection impedance 3 is inserted into the middle of the grounding wire 2. The measuring end of a measuring device 4 such as a tester is connected to the shielding layer 12 side connection end A and the ground side connection end B of the detection impedance 3, so that the resistance value at both ends of the detection impedance 3 can be measured. .
検出インピーダンス３としては、それ自身の抵抗値が既
知である任意の抵抗体を挿入したものであっても良いが
、例えば、接地線２中を流れる接地線電流ｉｅを検出し
て解析することによって、ケーブル絶縁体１１の劣化度
合を検出する如き劣化診断装置であっても良い。上記の
ような劣化診断装置は、接地線２の中間部に挿入される
ものであり、本発明を実施するには好適である。なおこ
の場合、該劣化診断装置の入力インピーダンスを事前に
測定しておく必要かある。As the detection impedance 3, an arbitrary resistor whose resistance value is known may be inserted, but for example, by detecting and analyzing the grounding line current ie flowing through the grounding line 2, , a deterioration diagnosis device that detects the degree of deterioration of the cable insulator 11 may be used. The deterioration diagnosis device as described above is inserted into the middle part of the grounding wire 2, and is suitable for carrying out the present invention. In this case, it is necessary to measure the input impedance of the deterioration diagnosis device in advance.
第２図の等価回路図において、Ｃａはケーブル絶縁体１
０と遮蔽層１２との間の静電容量、Ｒｄは検出インピー
ダンスの抵抗値であり、この抵抗値は既知であることを
前提とする。またＣｄは検出インピーダンスの入力静電
容量である。この等価回路図に示すように、遮蔽層１２
と大地との間の閉ループでは、検出インピーダンスの抵
抗Ｒｄとシース抵抗Ｒｓとは並列接続されていると考え
ることができる。従って、検出インピーダンス３の接地
線２への接続両端Ａ、Ｂにおいて測定器４てその抵抗値
をδ１１定すると、抵抗Ｒｄとシース抵抗Ｒｓとの並列
合成抵抗を測定したことになる。In the equivalent circuit diagram in Figure 2, Ca is the cable insulator 1
The capacitance Rd between 0 and the shielding layer 12 is the resistance value of the detection impedance, and it is assumed that this resistance value is known. Further, Cd is the input capacitance of the detection impedance. As shown in this equivalent circuit diagram, the shielding layer 12
In the closed loop between the ground and the ground, the resistance Rd of the detection impedance and the sheath resistance Rs can be considered to be connected in parallel. Therefore, when the resistance value of the measuring device 4 is determined by δ11 at both ends A and B of the connection of the detection impedance 3 to the grounding wire 2, the parallel combined resistance of the resistance Rd and the sheath resistance Rs is measured.
ここで、測定器４の測定抵抗値Ｒは
Ｒ： Ｒｄ−Ｒ５
Ｒｄ十Ｒｓ
て示されるので、シース抵抗Ｒｓは既知の検出インピー
ダンスの抵抗値Ｒｄと測定抵抗値ＲよりＲ８： Ｒｄ−
Ｒ
Ｒｄ−Ｒ
の式て算出することかできる。Here, the measured resistance value R of the measuring device 4 is expressed as R: Rd-R5 Rd+Rs, so the sheath resistance Rs is calculated from the resistance value Rd of the known detection impedance and the measured resistance value R8: Rd-
It can be calculated using the formula RRd-R.
測定抵抗値Ｒは、Ｒｓ）Ｒｄならばシース抵抗Ｒｓが充
分大きいことになるのでＲｄの値に近くなり、Ｒｓ（Ｒ
ｄならばシース抵抗Ｒｓが小ざいことになり、劣化した
シース抵抗の抵抗値として読むことができる。If the measured resistance value R is Rs)Rd, the sheath resistance Rs is sufficiently large, so the measured resistance value R will be close to the value of Rd.
If d, the sheath resistance Rs is small and can be read as the resistance value of the deteriorated sheath resistance.
ところで、ケーブル中の水トリー劣化部等において局部
電池作用により直流電位が生成されることが知られてい
る。局部電池作用により電位か発生している場合、第２
図の等価回路においてシース抵抗Ｒｓと直列に直流電源
が接続されていることとなり、本発明法によるシース抵
抗測定値は正確ざに欠ける恐れがある。本発明者らが、
局部電池の影響を考慮した模擬測定回路により実験を行
ったところ、ＤＣ±１．０Ｖ程度の局部電池が発生して
いる場合はシース抵抗測定に影響が生ずるものの、実線
路において発生する局部電池電位は最大で０．５Ｖ程度
であり、またケーブル布設環境によっては局部電池がほ
とんど発生しないこともあり、局部電池電位が極めて小
ざい場合は測定値に与える影響は無視し得、実線路では
充分実用に供し得ることか確認された。By the way, it is known that a direct current potential is generated due to local battery action in water tree-degraded parts of cables. If a potential is generated due to local battery action, the second
In the equivalent circuit shown in the figure, a DC power source is connected in series with the sheath resistance Rs, and the sheath resistance measurement value obtained by the method of the present invention may lack accuracy. The inventors
An experiment was conducted using a simulated measurement circuit that took into account the influence of local batteries, and it was found that if a local battery of about DC ±1.0V was generated, it would affect the sheath resistance measurement, but the local battery potential generated on the actual line is about 0.5V at maximum, and depending on the cable installation environment, local batteries may hardly occur.If the local battery potential is extremely small, the effect on the measured value can be ignored, and it is sufficient for practical use on actual lines. It was confirmed that it could be used for
また本実施例は単相測定の場合を例示しているか、この
場合検出インピーダンス３の接地線２への接続両端Ａ、
Ｂ間に、線路電圧をケーブル１の静電容量Ｃａと入力静
電容量Ｃｄとで分圧した交流電圧（充電電圧）か発生し
、この充７＆電圧の影響で、測定器４として内蔵電源電
圧が小ざいテスター（１，５Ｖ程度）を用いると、正確
なシース抵抗測定ができないことかある。Also, this embodiment exemplifies the case of single-phase measurement; in this case, the detection impedance 3 is connected to the grounding wire 2 at both ends A,
Between B, an AC voltage (charging voltage) is generated by dividing the line voltage by the capacitance Ca of the cable 1 and the input capacitance Cd, and due to the influence of this charging voltage, the built-in power supply voltage as the measuring device 4 If a small tester (about 1.5V) is used, it may not be possible to accurately measure the sheath resistance.
上記問題の解決法として、第１に、単相測定とせず３相
線路の各遮蔽層から接地線を引出しこれらを一括して測
定を行えば、上記充電電圧は３相で平衡してほぼＯＶと
なる。従って３相−括測定とすれば充電電圧の影響は無
視てきる。第２に、あくまで単相測定を行う場合は、測
定器４として内蔵電源電圧が大といテスター、例えば２
５Ｖメガ−等を使用すると上記充電電圧の影響は無視で
きることか本発明者らの実験で確認されている。As a solution to the above problem, firstly, instead of single-phase measurement, if you pull out the grounding wire from each shielding layer of the three-phase line and measure them all at once, the charging voltage will be balanced across the three phases and will be approximately OV. becomes. Therefore, if the three-phase measurement is carried out, the influence of the charging voltage can be ignored. Second, when performing single-phase measurements, use a tester with a high built-in power supply voltage as the measuring device 4, such as a 2-phase tester.
It has been confirmed through experiments by the inventors that the influence of the charging voltage can be ignored if a 5V mega-voltage or the like is used.
実験結果によると、ケーブル静電容量Ｃａや対地電圧、
入力静電容量Ｃｄとから計算した充電電圧よりも高い電
源電圧を内蔵するテスターを使用すると、概ね充電電圧
の影響を受けずにシース抵抗Ｒｓの測定が可能であるこ
とが確認された。According to the experimental results, cable capacitance Ca, voltage to ground,
It was confirmed that by using a tester with a built-in power supply voltage higher than the charging voltage calculated from the input capacitance Cd, it was possible to measure the sheath resistance Rs almost without being affected by the charging voltage.
以上説明した本発明のシース抵抗測定方法は、前述した
通り、例えば検出インピーダンス３として接地線電流ｉ
ｅに基づいてケーブル絶縁体１１の劣化度合を活線状態
において診断する如き劣化診断装置を用い、該劣化診断
装置にてケーブル絶縁体１１の診断を行う前に、シース
１３か健全な絶縁抵抗を有しているか否かを確認する場
合に好適である。この場合、絶縁体１１の劣化診断か実
施可能かどうか、あるいはその結果が信頼できるもので
あるのかどうかを確認でとるという利点がある。As described above, the sheath resistance measuring method of the present invention described above uses, for example, a ground wire current i as the detection impedance 3.
Using a deterioration diagnosis device that diagnoses the degree of deterioration of the cable insulator 11 in a live line state based on This is suitable for checking whether the In this case, there is an advantage in that it can be confirmed whether the deterioration diagnosis of the insulator 11 is possible or whether the results are reliable.
［効果］
以上説明した通りの本発明の活線下ケーブルシースの絶
縁抵抗測定方法によれば、ケーブル線路が活線状態のま
まで、しかも遮蔽層の接地線を切り離すことなくシース
抵抗の測定が行えるので、ケーブル線路の保守・管理に
極めて有効である。[Effect] According to the method for measuring the insulation resistance of a cable sheath under a live wire of the present invention as explained above, the sheath resistance can be measured while the cable line remains in a live wire state and without disconnecting the ground wire of the shielding layer. This makes it extremely effective for the maintenance and management of cable lines.
また、ケーブル絶縁層の活線劣化診断装置が接地線中に
挿入されている場合、本発明で言う検出インピーダンス
として該劣化診断装置を代用することかでき、この場合
はテスター等のζ１定器のみ用意して劣化診断装置の入
力端の抵抗を♂１定すれば容易にシース抵抗値か算出て
ざるという利点もある。Furthermore, if a live-line deterioration diagnostic device for the cable insulation layer is inserted into the ground wire, the deterioration diagnostic device can be used as a detection impedance in the present invention, and in this case, only a ζ1 constant device such as a tester is used. There is also the advantage that the sheath resistance value can be easily calculated if the resistance at the input end of the deterioration diagnosis device is set to ♂1.
第１図は本発明にかかる活線下ケーブルシースの絶縁抵
抗測定方法の一例を示す回路図、第２図は第１図の等価
回路図を夫々示している。FIG. 1 is a circuit diagram showing an example of a method for measuring insulation resistance of a cable sheath under a live wire according to the present invention, and FIG. 2 is an equivalent circuit diagram of FIG. 1.
Claims (1)
ダンスが挿入されてなるケーブル線路において、該検出
インピーダンスの両端において測定器で抵抗値を測定し
、前記検出インピーダンスの抵抗値と、測定器により実
測された測定抵抗値とからケーブルシースの抵抗値を算
出することを特徴とする活線下ケーブルシースの絶縁抵
抗測定方法。In a cable line in which a detection impedance with a known resistance value is inserted into the ground wire of the cable shielding layer, the resistance value is measured with a measuring device at both ends of the detection impedance, and the resistance value of the detection impedance and the actual measurement with the measuring device are measured. A method for measuring insulation resistance of a cable sheath under a live wire, characterized in that the resistance value of the cable sheath is calculated from the measured resistance value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2202036A JP3010367B2 (en) | 1990-07-30 | 1990-07-30 | Insulation resistance measurement method of cable sheath under hot wire |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2202036A JP3010367B2 (en) | 1990-07-30 | 1990-07-30 | Insulation resistance measurement method of cable sheath under hot wire |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0486571A true JPH0486571A (en) | 1992-03-19 |
| JP3010367B2 JP3010367B2 (en) | 2000-02-21 |
Family
ID=16450873
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2202036A Expired - Fee Related JP3010367B2 (en) | 1990-07-30 | 1990-07-30 | Insulation resistance measurement method of cable sheath under hot wire |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3010367B2 (en) |
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| CN111856206A (en) * | 2020-06-30 | 2020-10-30 | 国网江苏省电力有限公司电力科学研究院 | Method and device for live detection of electrical connection defects of cable metal sheath |
Families Citing this family (1)
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|---|---|---|---|---|
| CN105137192B (en) * | 2015-09-10 | 2017-11-17 | 山东康威通信技术股份有限公司 | Cable shielding layer earthing performance monitoring device and method based on complex impedance measurement |
-
1990
- 1990-07-30 JP JP2202036A patent/JP3010367B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109239548A (en) * | 2018-08-30 | 2019-01-18 | 中国船舶重工集团公司第七〇五研究所 | A kind of equipment and measurement method of rapid survey insulation |
| CN111856206A (en) * | 2020-06-30 | 2020-10-30 | 国网江苏省电力有限公司电力科学研究院 | Method and device for live detection of electrical connection defects of cable metal sheath |
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