JPH07306241A - Insulation deterioration judging method for power cable - Google Patents
Insulation deterioration judging method for power cableInfo
- Publication number
- JPH07306241A JPH07306241A JP12078194A JP12078194A JPH07306241A JP H07306241 A JPH07306241 A JP H07306241A JP 12078194 A JP12078194 A JP 12078194A JP 12078194 A JP12078194 A JP 12078194A JP H07306241 A JPH07306241 A JP H07306241A
- Authority
- JP
- Japan
- Prior art keywords
- voltage
- cable
- test
- leakage current
- power cable
- 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.)
- Pending
Links
Landscapes
- Testing Relating To Insulation (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、電力ケーブルの絶縁
劣化、特に架橋ポリエチレン絶縁ビニルシースケーブル
（ＣＶケーブル）の水トリー劣化に係る電力ケーブルの
絶縁劣化判定法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining insulation deterioration of a power cable, and particularly to a deterioration of a power cable insulation deterioration caused by a water tree deterioration of a crosslinked polyethylene insulated vinyl sheath cable (CV cable).
【０００２】[0002]
【従来の技術】電力ケーブルの絶縁劣化、特に架橋ポリ
エチレン絶縁ビニルシースケーブル（ＣＶケーブル）の
水トリー劣化の判定法としては、ケーブル絶縁体に直流
電圧を印加して、漏れ電流を測定する方法がよく用いら
れている。この他にケーブル絶縁体に交流電圧を印加し
たとき、絶縁体に水トリーがあれば、その整流作用によ
り直流成分を発生させるので、送電中のケーブルの接地
線よりこの直流成分を検出して劣化判定を行う方法も行
われている。2. Description of the Related Art As a method for judging deterioration of insulation of a power cable, particularly deterioration of a water tree of a crosslinked polyethylene-insulated vinyl sheath cable (CV cable), a method of applying a DC voltage to a cable insulator and measuring a leak current is preferable. It is used. In addition to this, when an AC voltage is applied to the cable insulator, if there is a water tree in the insulator, a rectifying action will generate a DC component, so this DC component will be detected and deteriorated from the ground wire of the cable during power transmission. A method of making a judgment is also used.
【０００３】[0003]
【発明が解決しようとする課題】ところで、上記漏れ電
流および直流成分を測定する方法は、いずれもナノアン
ペアクラスの微小電流を測定して判定を行わなければな
らないため、コロナやケーブル端末部の表面漏れ電流な
どのノイズの影響を受け易く、測定精度を上げることが
大きな課題となっている。このため、表面漏れ電流を取
り込まないようにガードをとり、部分放電を発生させな
いような対策が必要である。By the way, in any of the above methods for measuring the leakage current and the DC component, it is necessary to measure the minute current of the nanoampere class to make the determination, and therefore the surface of the corona or the cable terminal portion is to be determined. Since it is easily affected by noise such as leakage current, increasing the measurement accuracy is a major issue. Therefore, it is necessary to take measures to prevent surface discharge current from being taken in and to prevent partial discharge.
【０００４】このため、正常ケーブルと劣化ケーブルで
の漏れ電流の測定値に、明らかな差が生じるように測定
手法や回路などを考案すれば、絶縁劣化の判定を容易に
することが可能である。Therefore, if a measurement method or a circuit is devised so that the measured values of the leakage currents of the normal cable and the deteriorated cable have a clear difference, it is possible to easily judge the insulation deterioration. .
【０００５】この発明の目的は、上述した従来技術で問
題となっている測定精度の低さを解消し、電力ケーブル
の劣化判定が容易に行うことができるような新たな測定
手法を提供することにある。An object of the present invention is to provide a new measuring method which can solve the above-described low measurement accuracy which is a problem in the prior art and can easily determine deterioration of a power cable. It is in.
【０００６】[0006]
【課題を解決するための手段および作用】この発明は電
力ケーブル、特にＣＶケーブルに直流耐電圧試験を行っ
た後に低電圧を印加して漏れ電流を測定すると、水トリ
ー劣化ケーブルでは正常ケーブルより大きな漏れ電流が
測定される点に注目し、耐電圧試験の前後に同じ電圧を
印加して漏れ電流を測定すると、漏れ電流値の増倍係数
が劣化ケーブルの方が正常ケーブルよりも明らかに大き
いことが本件発明者の研究結果から知見され、これを利
用して絶縁劣化の診断の精度を大幅に向上させたもので
ある。According to the present invention, when a leakage current is measured by applying a low voltage to a power cable, especially a CV cable after performing a DC withstanding voltage test, the water tree deteriorated cable is larger than a normal cable. Paying attention to the fact that the leakage current is measured, when the same voltage is applied before and after the withstanding voltage test and the leakage current is measured, the multiplication factor of the leakage current value is clearly higher in the deteriorated cable than in the normal cable. However, the inventors of the present invention have found out from the results of the research, and by utilizing this, the accuracy of diagnosis of insulation deterioration is significantly improved.
【０００７】[0007]
【実施例】以下、この発明の実施例を説明する。直流耐
電圧試験の前後における漏れ電流値の増加係数（Ｉ2 ／
Ｉ1 ）を劣化判定の基準とすため、正常ケーブルと劣化
ケーブルで漏れ電流Ｉ1 ，Ｉ2 の比（Ｉ2 ／Ｉ1 ）に差
を見出せるように、直流耐電圧試験の前後の印加電圧Ｖ
1 （＝Ｖ2 ）を選択しなければならない。実験を重ねた
結果、ケーブル絶縁体中の平均電界をＥとして、０．５
ｋＶ／ｍｍ≦Ｅ≦１５ｋＶ／ｍｍを満足するような電圧
Ｖ1 を印加したときに、Ｉ2 ／Ｉ1 の値に正常ケーブル
と劣化ケーブルでの差が表れるため、電圧Ｖ1 はこの電
界範囲を満足するように選定する。このようにして劣化
判定をした場合、漏れ電流の比（Ｉ2／Ｉ1 ）＞５のと
きは確実に絶縁劣化であると判定することができる。Embodiments of the present invention will be described below. Increasing coefficient of leakage current value before and after DC withstanding voltage test (I 2 /
Since I 1 ) is used as a criterion for deterioration determination, the applied voltage before and after the DC withstanding voltage test is performed so that the difference (I 2 / I 1 ) between the leakage currents I 1 and I 2 between the normal cable and the deteriorated cable can be found. V
One (= V 2 ) must be selected. As a result of repeated experiments, assuming that the average electric field in the cable insulator is E, 0.5
When a voltage V 1 satisfying kV / mm ≦ E ≦ 15 kV / mm is applied, a difference between the normal cable and the deteriorated cable appears in the value of I 2 / I 1 , so that the voltage V 1 is in this electric field range. Is selected so that When the deterioration is determined in this manner, it can be reliably determined that the insulation is deteriorated when the leakage current ratio (I 2 / I 1 )> 5.
【０００８】表１は絶縁体厚さ９ｍｍの３３ｋＶ級のＣ
Ｖケーブルを用いて、劣化していないもの（正常ケーブ
ル）と、水トリー劣化しているもの（劣化ケーブル）を
供試ケーブルとして、直流耐電圧試験の前後に直流耐電
圧試験の電圧Ｖ0 より低い同じ電圧Ｖ1 ＝Ｖ2 を印加し
て漏れ電流Ｉ1 ，Ｉ2 を測定した。そして、漏れ電流Ｉ
1 ，Ｉ2 の測定値から、これらの比（Ｉ2 ／Ｉ1 ）の値
を算出した結果を示す。Table 1 shows C of 33 kV class with an insulator thickness of 9 mm.
Using the V cable, the one that is not deteriorated (normal cable) and the one that is deteriorated in the water tree (deteriorated cable) are used as test cables, and the voltage V 0 of the DC withstanding voltage test is used before and after the DC withstanding voltage test. Leakage currents I 1 and I 2 were measured by applying the same low voltage V 1 = V 2 . Then, the leakage current I
The results of calculating the values of these ratios (I 2 / I 1 ) from the measured values of 1 and I 2 are shown.
【０００９】[0009]
【表１】 [Table 1]
【００１０】電圧印加の方法は、図１に示すように、直
流耐電圧試験の前後に印加する低い電圧Ｖ1 ＝Ｖ2 を３
ｋＶ，６０ｋＶおよび−６０ｋＶの３種類とし、時間ｔ
1 およびｔ2 は１５分間印加して漏れ電流Ｉ1 ，Ｉ2 を
測定した。直流耐電圧試験の印加時間ｔ0 は１０分間で
あり、直流耐電圧として印加する電圧Ｖ0 は８６ｋＶで
ある。即ち、図１に示すようなステップ電圧を印加し
た。As shown in FIG. 1, the voltage application method is performed by applying a low voltage V 1 = V 2 of 3 before and after the DC withstanding voltage test.
There are three types, kV, 60 kV and −60 kV, and time t
Leakage currents I 1 and I 2 were measured by applying 15 minutes at 1 and t 2 . The application time t 0 of the DC withstanding voltage test is 10 minutes, and the voltage V 0 applied as the DC withstanding voltage is 86 kV. That is, a step voltage as shown in FIG. 1 was applied.
【００１１】表１に示すとおり、正常ケーブルにおける
漏れ電流の比（Ｉ2 ／Ｉ1 ）の値と劣化ケーブルにおけ
る漏れ電流の比（Ｉ2 ／Ｉ1 ）の値から、極めて差が生
じ、絶縁劣化を容易に判別することが可能となる。ま
た、直流耐電圧試験の前後に印加する電圧の極性を直流
耐電圧試験の電圧の極性と逆極性にすると、同極性の場
合よりも正常ケーブルと劣化ケーブルにおける漏れ電流
の比（Ｉ2 ／Ｉ1 ）の差が大きくなり、さらに容易に判
別することができる。As shown in Table 1, there is an extremely large difference between the leakage current ratio (I 2 / I 1 ) in the normal cable and the leakage current ratio (I 2 / I 1 ) in the deteriorated cable. It is possible to easily determine the deterioration. When the polarity of the voltage applied before and after the DC withstanding voltage test is set to be opposite to the polarity of the voltage of the DC withstanding voltage test, the ratio of leakage current (I 2 / I) between the normal cable and the deteriorated cable is higher than that in the case of the same polarity. The difference in 1 ) becomes large, and it can be more easily discriminated.
【００１２】なお、直流耐電圧試験の前の印加電圧Ｖ1
＝３ｋＶのときは、正常ケーブルの漏れ電流の比（Ｉ2
／Ｉ1 ）の値が５以上になり、劣化を誤判定しているよ
うに見受けられるが、このときは平均電界ＥがＥ＝０．
３３ｋＶで、本発明で前提としている平均電界範囲
（０．５ｋＶ／ｍｍ≦Ｅ≦１５ｋＶ／ｍｍ）を逸脱して
いる場合である。The applied voltage V 1 before the DC withstanding voltage test
= 3 kV, the ratio of the leakage current of the normal cable (I 2
/ I 1 ) becomes 5 or more, and it seems that the deterioration is erroneously determined, but at this time, the average electric field E is E = 0.
This is a case where the value of 33 kV deviates from the average electric field range (0.5 kV / mm ≦ E ≦ 15 kV / mm) which is the premise of the present invention.
【００１３】[0013]
【発明の効果】以上説明したとおり、この発明の電力ケ
ーブルの絶縁劣化判定法によれば、電力ケーブルの劣化
判定を確実に行うことが可能となった。即ち、従来の直
流漏れ電流を測定する劣化判定手法では、各々の供試ケ
ーブルの漏れ電流値を判定基準としているため、各回の
測定でノイズの影響により正確な漏れ電流が測定できな
いという危惧があったが、この発明によれば同一ケーブ
ルで漏れ電流の増加率を判定基準としているため、ノイ
ズの影響が相殺され、それだけ信頼性を高めることが可
能となった。As described above, according to the method for judging the deterioration of the power cable according to the present invention, it becomes possible to reliably judge the deterioration of the power cable. That is, in the conventional deterioration determination method for measuring DC leakage current, since the leakage current value of each test cable is used as the determination reference, there is a concern that accurate leakage current cannot be measured due to the influence of noise in each measurement. However, according to the present invention, since the increase rate of the leakage current is used as the criterion in the same cable, the influence of noise is canceled out, and the reliability can be improved accordingly.
【図１】この発明で使用する直流耐電圧試験とその前後
で印加する電圧値と印加時間を示すグラフである。FIG. 1 is a graph showing a DC withstand voltage test used in the present invention, a voltage value applied before and after the test, and an application time.
Claims (2)
て、これを実施する前に、耐電圧試験電圧Ｖ0 より低い
電圧Ｖ1 を供試ケーブルに印加し、このときの漏れ電流
Ｉ1 を測定し、その後、耐電圧試験電圧Ｖ0 を印加し、
耐電圧試験を行った後、供試ケーブルを接地し、最初に
印加した電圧Ｖ1 と同じ電圧Ｖ2 （Ｖ1＝Ｖ2 ）を印加
し、このときの漏れ電流Ｉ2 を測定し、これら耐電圧試
験の前後に耐電圧試験電圧Ｖ0 より低い電圧Ｖ1 ，Ｖ2
を印加して得られた漏れ電流の測定値Ｉ1 ，Ｉ2 より漏
れ電流の比の値（Ｉ2 ／Ｉ1 ）を求め、この値により電
力ケーブルの絶縁劣化を判定する電力ケーブルの絶縁劣
化判定法。1. In a DC withstand voltage test of a power cable, a voltage V 1 lower than a withstand voltage test voltage V 0 is applied to a test cable before performing this, and a leak current I 1 at this time is measured. Then, a withstand voltage test voltage V 0 is applied,
After performing the withstand voltage test, the test cable is grounded, the same voltage V 2 (V 1 = V 2 ) as the voltage V 1 applied first is applied, and the leakage current I 2 at this time is measured. Voltages V 1 and V 2 lower than withstand voltage test voltage V 0 before and after withstand voltage test
The leakage current ratio value (I 2 / I 1 ) is obtained from the measured leakage current values I 1 and I 2 obtained by applying the voltage, and the insulation degradation of the power cable is determined from this value. Judgment method.
判定法において、耐電圧試験前に印加した電圧Ｖ1 並び
に耐電圧試験後に印加した電圧Ｖ2 の極性を、耐電圧試
験電圧Ｖ0 と逆極性にして印加し、それぞれの漏れ電流
Ｉ1 ，Ｉ2 を測定する電力ケーブルの絶縁劣化判定法。2. The method for determining insulation deterioration of a power cable according to claim 1 , wherein the polarities of the voltage V 1 applied before the withstanding voltage test and the voltage V 2 applied after the withstanding voltage test are defined as the withstanding voltage test voltage V 0 . A method of determining insulation deterioration of a power cable, which applies reverse polarities and measures leakage currents I 1 and I 2 , respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12078194A JPH07306241A (en) | 1994-05-11 | 1994-05-11 | Insulation deterioration judging method for power cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12078194A JPH07306241A (en) | 1994-05-11 | 1994-05-11 | Insulation deterioration judging method for power cable |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07306241A true JPH07306241A (en) | 1995-11-21 |
Family
ID=14794848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12078194A Pending JPH07306241A (en) | 1994-05-11 | 1994-05-11 | Insulation deterioration judging method for power cable |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07306241A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111025090A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | Cable life prediction method based on leakage current difference coefficient |
| CN111025092A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | XLPE cable terminal air gap defect safety intelligent and rapid assessment method |
| CN111025095A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | XLPE cable terminal insulation reliability intelligent and rapid assessment method |
-
1994
- 1994-05-11 JP JP12078194A patent/JPH07306241A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111025090A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | Cable life prediction method based on leakage current difference coefficient |
| CN111025092A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | XLPE cable terminal air gap defect safety intelligent and rapid assessment method |
| CN111025095A (en) * | 2019-11-19 | 2020-04-17 | 云南电网有限责任公司临沧供电局 | XLPE cable terminal insulation reliability intelligent and rapid assessment method |
| CN111025090B (en) * | 2019-11-19 | 2022-04-26 | 云南电网有限责任公司临沧供电局 | Cable life prediction method based on leakage current difference coefficient |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH0726985B2 (en) | Insulation deterioration diagnosis method for power cables | |
| US5276401A (en) | Method for diagnosing an insulation deterioration of an electric apparatus | |
| Eager et al. | High voltage VLF testing of power cables | |
| EP0437214B1 (en) | Method for diagnosing an insulation deterioration of an electric apparatus | |
| JPH07306241A (en) | Insulation deterioration judging method for power cable | |
| JP3317391B2 (en) | Method and apparatus for diagnosing insulation deterioration of a live power cable | |
| JPS6331747B2 (en) | ||
| JP2876322B2 (en) | Diagnosis method for insulation deterioration of CV cable | |
| JPH0580630B2 (en) | ||
| JP3084154B2 (en) | Estimation method of anticorrosion potential of buried pipe | |
| JP3629424B2 (en) | CV cable insulation diagnosis method | |
| JPH1078472A (en) | Method for diagnosing deterioration of cv cable | |
| JP3092772B2 (en) | Diagnosis method for insulation deterioration of power cable | |
| JPH10160778A (en) | Method and device for diagnosing insulation deferioration of live, power cable | |
| JP4681391B2 (en) | Degradation diagnosis method for low-voltage cables | |
| JPH09304467A (en) | Method for diagnosing insulation deterioration of electric insulator | |
| JP2003084028A (en) | Hot line diagnostic method for power cable | |
| JPH0378588B2 (en) | ||
| JPH0331776A (en) | Diagnostic device for insulation deterioration of cv cable | |
| JP3034651B2 (en) | Diagnosis method for insulation of CV cable | |
| JP2612648B2 (en) | Deterioration judgment method for insulation of three-phase power cable | |
| JP3853134B2 (en) | Estimating remaining life of power cables | |
| JPH0331775A (en) | Diagnostic method for insulation deterioration of cv cable | |
| JPH0562309B2 (en) | ||
| JPS61234372A (en) | Insulation deterioration test for power cable |