JPH03218481A - Method and device for diagnosing insulation degradation of cv cable - Google Patents
Method and device for diagnosing insulation degradation of cv cableInfo
- Publication number
- JPH03218481A JPH03218481A JP32564889A JP32564889A JPH03218481A JP H03218481 A JPH03218481 A JP H03218481A JP 32564889 A JP32564889 A JP 32564889A JP 32564889 A JP32564889 A JP 32564889A JP H03218481 A JPH03218481 A JP H03218481A
- Authority
- JP
- Japan
- Prior art keywords
- current
- cable
- pulsating
- deterioration
- component
- 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 abstract description 26
- 238000000034 method Methods 0.000 title claims description 22
- 230000015556 catabolic process Effects 0.000 title abstract description 3
- 238000006731 degradation reaction Methods 0.000 title abstract 2
- 230000006866 deterioration Effects 0.000 claims description 47
- 238000001514 detection method Methods 0.000 claims description 12
- 239000004020 conductor Substances 0.000 abstract description 11
- 240000005572 Syzygium cordatum Species 0.000 description 22
- 235000006650 Syzygium cordatum Nutrition 0.000 description 22
- 238000003745 diagnosis Methods 0.000 description 10
- 230000010349 pulsation Effects 0.000 description 9
- 238000010586 diagram Methods 0.000 description 8
- 239000012212 insulator Substances 0.000 description 8
- 238000012360 testing method Methods 0.000 description 7
- 239000003990 capacitor Substances 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 239000000284 extract Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
Landscapes
- Testing Relating To Insulation (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、活線下においてＣＶケーブルの水トリー等に
よる絶縁劣化の程度を診断する絶縁劣化診断方法および
装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an insulation deterioration diagnosis method and apparatus for diagnosing the degree of insulation deterioration due to water tree etc. of a CV cable under live wires.
［従来の技術］
一般的に、電力ケーブルは布設後の経年変化により電気
絶縁体の絶縁性能が低下する。特に、ＣＶケーブルでは
架橋ポリエチレン絶縁体に樹状の亀裂が生じ、この亀裂
に水分が侵入する所謂水トリ一の発生が絶縁劣化の主な
原囚であることが知られている。このような絶縁性能の
低下は、放置すると進展して早晩大きな絶縁破壊事故に
つながる慣れがある。従って、ケーブルの絶縁抵抗の変
化を把握し、劣化を早期に発見することが極めて重要で
ある。このため、従来から種々の絶縁測定方法が知られ
ているが、特に近年では測定時に送電を停止することな
く活線状態で診断する方法が幾つか提案ざれており、常
時の状態監視も可能である等の有利な点が多いため注目
ざれている。[Prior Art] Generally, the insulation performance of the electric insulator of a power cable deteriorates due to aging after installation. In particular, it is known that in CV cables, dendritic cracks occur in the crosslinked polyethylene insulation, and the occurrence of so-called water trapping, in which water enters the cracks, is the main cause of insulation deterioration. If left untreated, this kind of deterioration in insulation performance will progress and sooner or later lead to a major dielectric breakdown accident. Therefore, it is extremely important to understand changes in cable insulation resistance and discover deterioration early. For this reason, various insulation measurement methods have been known for a long time, but in recent years in particular, several methods have been proposed for diagnosing live wires without stopping power transmission during measurement, making it possible to constantly monitor the condition. It is attracting attention because of its many advantages.
このような常時監視を行なう方法としては、従来では例
えば特公昭６０−８４６５号公報等に記載されているよ
うに送電交流電流に直流電流を重畳ざせ、この結果とし
て検出ざれるケーブル漏洩電流の直流成分からケーブル
の絶縁抵抗を求めて評価する所謂直流重畳法や、或は特
開昭６０−１８５１７１号公報等に記載ざれているよう
に送電電圧波形と電流波形とを測定し、誘電圧接を求め
て評価する所謂ｊａｎδ法が一般に用いられている。ま
た、持にＣＶケーブルの場合では特開昭５９−２０２０
７５号公報において水トリーに電流整流作用があるとし
て、交流送電中のケーブル漏洩電流の直流分を測定し、
その方向と絶対値とから水トリーの分布と長き及び体積
を推定する方法が開示ざれている。Conventionally, as a method for performing such constant monitoring, as described in Japanese Patent Publication No. 60-8465, etc., a direct current is superimposed on the power transmission alternating current, and as a result, the undetected direct current of the cable leakage current is detected. The so-called DC superposition method is used to determine and evaluate the insulation resistance of the cable from its components, or the dielectric voltage is determined by measuring the transmission voltage waveform and current waveform as described in Japanese Patent Application Laid-open No. 60-185171. The so-called jan δ method is generally used. In addition, in the case of CV cable, Japanese Patent Application Laid-Open No. 59-2020
In Publication No. 75, assuming that the water tree has a current rectifying effect, the DC component of the cable leakage current during AC power transmission was measured,
A method for estimating the distribution, length, and volume of water trees from their directions and absolute values is disclosed.
［発明が解決しようとする課題］
しかしながら、上述した公知の従来方法は何れも絶縁劣
化を早期に且つ正確に発見したいという要求を必ずしも
充分に満足し得る方法ではない。[Problems to be Solved by the Invention] However, none of the above-mentioned known conventional methods can fully satisfy the demand for early and accurate detection of insulation deterioration.
即ち、第１に述べた直流重畳法は一般的に劣化の程度に
対する検出感度が悪いときれ、相当に程度の激しい劣化
でなければ検出ざれないという問題がある。また測定時
に数１０Ｖ程度の直流重畳電圧を必要とし、このため直
流電源を別個に準備しなければならない。That is, the first-mentioned DC superimposition method generally suffers from poor detection sensitivity with respect to the degree of deterioration, and has the problem that it cannot be detected unless the degree of deterioration is extremely severe. Furthermore, a DC superimposed voltage of approximately several tens of volts is required during measurement, and therefore a separate DC power source must be prepared.
一方、ｊａｎδ法ではケーブル全体にわたる劣化は検出
ざれるものの、水トリーのような局部的な劣化に対する
検出感度は悪いという欠点が知られている。On the other hand, although the JAN δ method cannot detect deterioration over the entire cable, it is known to have a drawback in that it has poor detection sensitivity for localized deterioration such as water trees.
更に、水トリ一の整流作用を利用する特開昭５９ ２
０２０７５号公報の場合では、同公報に記述ざれている
ようにケーブル絶縁体に導体側から発生する所謂内導水
トリーとシース側から発生する外導水トリーとでは、発
生する直流電流が互いに逆極性であることから、両種の
水トリーが同時に発生した場合には検出ざれる直流電流
は互いに打ち消し合って充分な測定ができなくなる慣れ
がある。Furthermore, Japanese Patent Application Laid-Open No. 59-2 utilizes the rectifying action of water filters.
In the case of Publication No. 02075, as described in the same publication, the so-called internal water conduction tree generated from the conductor side of the cable insulator and the external water conduction tree generated from the sheath side have opposite polarity of generated DC current. For this reason, when both types of water trees occur at the same time, the undetected DC currents cancel each other out, making it impossible to make sufficient measurements.
上述のような問題点に鑑み、本発明者らが水トリー現象
について鋭意研究した結果、次のような新事実を発見し
た。すなわち、測定対象とする電力ケーブルに交流電圧
を印加し、この印加交流電圧の振幅を零から次第に大き
くしてゆく過程で、その接地線電流のうち士数Ｈｚ以下
の準直流成分を検出した場合に、
■ 印加交流電圧の振幅が或る値に達すると脈動電流が
検出ざれる。In view of the above-mentioned problems, the present inventors conducted intensive research on the water tree phenomenon and discovered the following new fact. In other words, when an AC voltage is applied to the power cable to be measured, and in the process of gradually increasing the amplitude of the applied AC voltage from zero, a quasi-DC component of the ground line current below a few Hz is detected. (2) When the amplitude of the applied AC voltage reaches a certain value, a pulsating current is detected.
■ 水トリー劣化が激しいケーブルほど、脈動の始まる
交流電圧の振幅値が小さい。■ The more severe the water tree deterioration of the cable, the smaller the amplitude value of the AC voltage at which pulsation begins.
■ 電流脈動の振幅は印加交流電圧の振幅に対して単調
に増加する。■ The amplitude of current pulsation increases monotonically with the amplitude of applied AC voltage.
かかる新知見に基づいて、本発明者らは新しい絶縁劣化
診断方法を先に提案した（特願平ｔ−ｉ６７９１０号）
。しかしながら、当該絶縁劣化診断を行なうに際しては
次のような問題があることが判明した。すなわち、接地
線電流より検出ざれる脈動電流の大きざから絶縁体の劣
化度合を判定するわけであるが、該脈動電流信号は微小
な信号であるため評価がきわめて困難なのである。また
、評価を容易とすべく脈動電流を単に増幅すると、雑音
電流成分も同時に増幅ざれてしまい、やはり評価が困難
となってしまう。Based on this new knowledge, the present inventors have previously proposed a new method for diagnosing insulation deterioration (Japanese Patent Application No. I67910).
. However, it has been found that there are the following problems when performing the insulation deterioration diagnosis. That is, the degree of deterioration of the insulator is determined from the magnitude of the pulsating current detected from the ground line current, but since the pulsating current signal is a minute signal, it is extremely difficult to evaluate. Furthermore, if the pulsating current is simply amplified to facilitate evaluation, the noise current component will also be amplified at the same time, making evaluation difficult.
従って本発明は、上記新事実に基づく絶縁劣化診断法に
おいて、より確実な絶縁劣化の検知が行ない得るＣＶケ
ーブルの絶縁劣化診断方法および装置を提供することを
目的とする。Therefore, an object of the present invention is to provide a method and apparatus for diagnosing insulation deterioration of a CV cable, which can detect insulation deterioration more reliably in an insulation deterioration diagnosing method based on the above-mentioned new facts.
［課題を解決するための手段］
本発明は上記目的を達成すべくなし、増幅されたもので
あって、その要旨とするところは、測定対象の電力ケー
ブルに交流電圧を印加し、その接地線より接地線電流を
検出し、該接地線電流より脈流成分を検出し、さらに該
脈流成分の中から特定周波数の信号のみを取り出してこ
れを増幅し、増幅し、増幅された特定周波数の脈流成分
の時間解析を行なうことにより、ケーブル絶縁体の劣化
の程度を検知することを特徴とするＣＶケーブルの絶縁
劣化診断方法、及び、ＣＶケーブルの遮蔽層より電位基
準との間を接続する接地線より接地線電流を検出する電
流検出装置と、検出した接地線電流より脈流成分を取り
出すローパスフィルタと、該ローパスフィルタの出力に
接続ざれる狭帯域増幅器と、該狭帯域増幅器の出力信号
を時間軸に表示する波形表示手段とを備えたことを特徴
とするＣＶケーブルの絶縁劣化診断装置にある。[Means for Solving the Problems] The present invention has been made to achieve the above object, and is amplified.The gist thereof is to apply an AC voltage to a power cable to be measured, and to apply an AC voltage to a power cable to be measured, Detects the grounding line current, detects the pulsating current component from the grounding line current, extracts only the signal of a specific frequency from the pulsating current component, amplifies it, and amplifies the amplified specific frequency signal. A method for diagnosing insulation deterioration of a CV cable, which is characterized by detecting the degree of deterioration of a cable insulator by time analysis of pulsating flow components, and a method for connecting a potential reference from a shielding layer of the CV cable. A current detection device that detects a ground line current from a ground line, a low pass filter that extracts a pulsating current component from the detected ground line current, a narrow band amplifier connected to the output of the low pass filter, and an output signal of the narrow band amplifier. A CV cable insulation deterioration diagnosing device is characterized in that it is equipped with a waveform display means for displaying the waveform on a time axis.
［作用］
第１請求項において、接地線電流より数Ｈｚ以下の脈流
成分を検出することにより、上記新知見に基づくケーブ
ル絶縁体の水トリー劣化検知が可能となる。ところが、
前述したように脈流成分は極めて微小な信号であるので
、増輻して評価し易いようにする必要がある。ここで、
脈流成分を単に広帯域増幅したのでは雑音電流成分も増
輻してしまうことになるので、特定周波数の脈流成分の
みを取り出して増幅するようにしてＳ／Ｎ比を向上きせ
る。このようにして得た特定周波数脈流成分の増幅信号
の時間解析を行ない、ケーブル絶縁体の劣化程度を検知
するものである。なお、接地線電流の検出を接地線を切
断せずに行えば、対地要領の影響を受けない、シースの
絶縁抵抗によらず測定できる、等の利点がある。[Function] In the first aspect, water tree deterioration of the cable insulator can be detected based on the above-mentioned new knowledge by detecting a pulsating flow component of several Hz or less than the ground wire current. However,
As mentioned above, since the pulsating flow component is an extremely small signal, it is necessary to increase the intensity to make it easier to evaluate. here,
If the pulsating flow component is simply amplified over a wide band, the noise current component will also increase, so the S/N ratio is improved by extracting and amplifying only the pulsating flow component at a specific frequency. The time analysis of the amplified signal of the specific frequency pulsating flow component obtained in this manner is performed to detect the degree of deterioration of the cable insulator. Note that if the grounding wire current is detected without cutting the grounding wire, there are advantages such as being unaffected by grounding conditions and being able to measure regardless of the insulation resistance of the sheath.
第３請求項において、ローパスフィルタにより接地線電
流から取り出した脈流成分を、狭帯域増幅器を用いて極
めて狭い範囲の周波数帯域において増輻することにより
、検出した金脈流成分のうちのある一つの特定周波数の
脈流成分信号のみを選択的に増輻することができる。従
って、Ｓ／Ｎ比を向上きせて増輻することができ、該信
号を波形表示手段に表示ざせることにより水トリー劣化
の評価を容易に行なうことができる。In the third claim, by amplifying the pulsating current component extracted from the ground wire current by a low-pass filter in an extremely narrow frequency band using a narrow band amplifier, one of the detected gold pulsating current components is It is possible to selectively amplify only the pulsating flow component signal of a specific frequency. Therefore, the S/N ratio can be improved and the signal can be increased, and water tree deterioration can be easily evaluated by displaying the signal on the waveform display means.
［実施例］
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
。[Example] An example of the present invention will be described in detail below based on the drawings.
第１図は本発明の劣化診断方法を実施するためのブロッ
ク図である。図において、Ｃｋは測定対象とするＣＶケ
ーブル等の供試電力ケーブルの導体と遮蔽層間の静電容
量であり、ａ側をケーブルの導体側、ｂ側を遮蔽層側と
している。Ｅは交流電源であり、一端を接地し、他端を
供試電力ケーブルの導体ａ側に接続する。ここで交流電
源Ｅにて供試電力ケーブルに電圧を印加すると、ケーブ
ルが有する静電容量Ｃｋに充電電流が流れ、遮蔽層ｂ側
から大地に接地線を通り接地線電流ｉｅが流れることに
なる。該接地線より接地線電流ｉｅを検出する役目を果
たすのが、遮蔽層ｂ側と大地との間に接続きれている電
流検出装置１、０である。FIG. 1 is a block diagram for implementing the deterioration diagnosis method of the present invention. In the figure, Ck is the capacitance between the conductor and the shielding layer of a test power cable such as a CV cable to be measured, and the a side is the conductor side of the cable and the b side is the shielding layer side. E is an AC power source, one end of which is grounded, and the other end connected to the conductor a side of the power cable under test. When a voltage is applied to the power cable under test from the AC power supply E, a charging current flows through the capacitance Ck of the cable, and a grounding line current ie flows from the shielding layer b side to the ground through the grounding wire. . Current detection devices 1 and 0, which are connected between the shielding layer b side and the ground, serve to detect the ground line current ie from the ground line.
電流検出装置１０にて検出し、増幅された接地線電流ｉ
ｅはローパスフィルター１に送出され、ここで接地線電
流ｉｅより脈流成分のみが取り出ざれる。ローパスフィ
ルター１の出力には、検出した上記脈流成分の中から特
定周波数の信号のみを取り出して増幅する増幅器２が接
続きれ、さらに該増幅器２の出力には、この増幅信号を
時間軸に表示するためのペングラフ、オシロスコープ等
の波形表示装置３が接続ざれている。Ground line current i detected and amplified by current detection device 10
e is sent to a low-pass filter 1, where only the pulsating flow component is extracted from the ground line current ie. The output of the low-pass filter 1 is connected to an amplifier 2 that extracts and amplifies only a signal of a specific frequency from the detected pulsating flow components, and the output of the amplifier 2 displays this amplified signal on the time axis. A waveform display device 3, such as a pen graph or an oscilloscope, is connected.
第２図は第１図に示すブロック図の回路構成図の一例を
示している。図中Ｅは交流電源であるが、ケーブルが活
線状態の場合において本発明を実施する場合は、印加ざ
れている線路電圧をそのまま利用すれば良く、交流電源
Ｅは不要となる。４は供試ＣＶケーブルであり、４１は
その導体、４２は絶縁体、４３は遮蔽層をそれぞれ示し
ている。FIG. 2 shows an example of a circuit configuration diagram of the block diagram shown in FIG. E in the figure is an AC power supply, but if the present invention is carried out when the cable is in a live state, the applied line voltage can be used as is, and the AC power supply E is not necessary. 4 is a test CV cable, 41 is its conductor, 42 is an insulator, and 43 is a shielding layer.
遮蔽層４３から大地に引き出し、増幅された接地線には
、変流器ＣＴ （第１図における電流検出装置１０に対
応する）がカップリングざれており、接地線中を流れる
接地線電流ｉｅは変流器ＣＴにより検出される。A current transformer CT (corresponding to the current detection device 10 in FIG. 1) is coupled to the amplified grounding wire drawn out from the shielding layer 43 to the ground, and the grounding line current ie flowing through the grounding wire is Detected by current transformer CT.
接地線より接地線電流ｉｅを検出する他の方法としては
、接地線に抵抗を挿入し、この抵抗の両端に現れる電圧
を利用する手段や、鉄心とホール素子を用いたクランブ
式電流検出器等を使用する手段などが挙げられる。しか
しながら抵抗による検出の場合、先ず接地線を切断して
抵抗を挿入せねばならず、また被測定ＣＶケーブルと大
地との間に電位差が発生することになり、その結果ケー
ブルー大地静電容量が測定に悪影響を及ぼすこととなる
ので好ましくない。これに対し、変流器ＣＴや上記クラ
ンブ式電流検出器等（すなわち接地線を切断しない電流
検出手段）では、上述の静電容量の問題を殆ど考慮せず
とも良く、また接地線を切断したりする等の加工を何等
施す必要がないので既設線路への適用が容易であり、さ
らに局部電池の影響を受けない等、様々な利点がある。Other methods for detecting the grounding wire current ie from the grounding wire include inserting a resistor into the grounding wire and utilizing the voltage appearing across the resistor, and using a clamp-type current detector using an iron core and a Hall element. Examples include means using . However, in the case of detection using a resistance, the ground wire must first be cut and a resistor inserted, and a potential difference will occur between the CV cable under test and the earth, and as a result, the cable-earth capacitance will be measured. This is not desirable as it will have a negative effect on On the other hand, with current transformers CT, the above-mentioned clamp-type current detectors, etc. (i.e., current detection means that do not cut the ground wire), there is almost no need to consider the above-mentioned capacitance problem, and there is no need to take the above-mentioned capacitance issue into account. Since there is no need to perform any processing such as heating, it is easy to apply to existing lines, and it has various advantages such as not being affected by local batteries.
ローパスフィルター１としては、図示するように遮蔽層
４３と大地との間にコンデンサＣｏを接続し、これより
コイルＬ Ｌ ＋コンデンサＣ，及びコイルＬ ２ ＋
コンデンサＣ２からなる２段の所謂定Ｋ型フィルタを用
いた場合を例示している。ローパスフィルター１は、ケ
ーブル導体４１への交流電源Ｅの印加により生ずる接地
線電流ｉｅの中から脈流成分のみを出力し、該出力は狭
帯域型の増幅器２へ入力ざれる。As the low-pass filter 1, as shown in the figure, a capacitor Co is connected between the shielding layer 43 and the ground, and from this, a coil L L + capacitor C, and a coil L 2 +
A case is illustrated in which a two-stage so-called constant K type filter including a capacitor C2 is used. The low-pass filter 1 outputs only the pulsating current component from the ground line current ie generated by application of the AC power source E to the cable conductor 41, and this output is input to the narrowband amplifier 2.
増幅器２としては、各種狭帯域型のものを用いることが
でとるが、本実施例では低周波帯でよく用いられる並列
Ｔ型ＣＲ回路２０を帰還回路に用いた帰還増幅器を使用
した場合を例示している。As the amplifier 2, various narrowband types can be used, but in this embodiment, a feedback amplifier using a parallel T-type CR circuit 20, which is often used in a low frequency band, as a feedback circuit is exemplified. are doing.
並列Ｔ型ＣＲ回路（Ｔｗｉｎ−Ｔ回路）２０は、２個の
同抵抗値の抵抗Ｒａ，ＲａとコンデンサｃｂからなるＴ
型回路、及び２個の同容量のコンデンサＣａ，Ｃａと抵
抗ＲｂからなるＴ型回路の並列回路で構成ざれ、コンデ
ンサｃｂ及び抵抗Ｒｂは、それぞれＣｂ＝２Ｃａ．Ｒｂ
＝Ｒａ／２の値とざれている。このように構成し、増幅
された並列Ｔ型ＣＲ回路２０は、ｆｏ− １／２ｎ ・
Ｃａ−Ｒａの周波数信号を最大｛ａ号で通過ぎせる周波
数特性を備えており、負帰還増幅器の帰還回路に該回路
を用いれば、上記ｆｏの周波数以外では負帰還が生じる
ため、周波数ｆ。の｛ｉ号の選択増輻、すなオ〕も脈流
成分の中からある一つの特定周波数のイａ号のみを取り
出して増輻することが可能となる。The parallel T-type CR circuit (Twin-T circuit) 20 is a T-type CR circuit (Twin-T circuit) consisting of two resistors Ra, Ra having the same resistance value and a capacitor cb.
It consists of a parallel circuit of a T-type circuit and a T-type circuit consisting of two capacitors Ca and Ca of the same capacity and a resistor Rb, and the capacitor cb and the resistor Rb are each Cb=2Ca. Rb
= Ra/2 value. The parallel T-type CR circuit 20 configured and amplified in this way has fo-1/2n.
It has a frequency characteristic that allows the Ca-Ra frequency signal to pass at a maximum frequency f. {selective increase of the i number, i.e. O] also makes it possible to extract and increase the intensity of only one specific frequency of the i number from among the pulsating flow components.
なお図中Ｇはアンプを示している。そして増幅器２の出
力は波形表示装置３に送出ざれ、脈流成分の特定周波数
４８号が時間軸に表示ざれる。Note that G in the figure indicates an amplifier. The output of the amplifier 2 is then sent to the waveform display device 3, and the specific frequency No. 48 of the pulsating flow component is displayed on the time axis.
第３図は上述の装置におけるローパスフィルタ１の出力
の、時間変化のグラフ図の一例であり、横軸に時間ｔ１
縦軸に電流■を示している。供試ＣＶケーブル４に交流
電圧が印加ざれている状態となると、遮蔽層４３には導
体４１との静電結合により印加交流電圧に応じた電荷が
誘起され、この時間変化のため大地との間に印加交流電
圧の周波数と同程度の周期で変動ずる電流（接地線電流
ｉｅ）が流れることになるが、これに加え絶縁体４２に
水トリー劣化が存在する場合には、前述の脈動電流が重
畳ざれることとなる。脈動電流とは印加交流電圧に依存
する電流以外の電流を言い、印加交流電圧の周波数以下
の周波数電流である。FIG. 3 is an example of a graph of the time change of the output of the low-pass filter 1 in the above-mentioned device, and the horizontal axis shows the time t1.
The vertical axis shows the current ■. When an AC voltage is applied to the test CV cable 4, a charge corresponding to the applied AC voltage is induced in the shielding layer 43 due to electrostatic coupling with the conductor 41, and due to this time change, the distance between the shielding layer 43 and the ground increases. A current (grounding line current ie) that fluctuates at a period comparable to the frequency of the applied AC voltage will flow, but if there is water tree deterioration in the insulator 42 in addition to this, the above-mentioned pulsating current will flow. They will be overlapped. The pulsating current refers to a current other than a current that depends on the applied AC voltage, and is a current with a frequency lower than the frequency of the applied AC voltage.
通常、印加交流電圧の周波数は５０Ｈｚ又は６０Ｈｚで
あるので、例えば５０Ｈｚ又は６０Ｈｚ以下の周波数信
号を通過させ得るようにローパスフィルタ１の回路を設
計すれば、第３図に示す如ぎ脈流成分のみを接地線電流
ｉｅ中から検出することができる。検出する脈流成分の
周波数は任意であるが、周波数が高い程対地容量の面で
不利となるため、５Ｈｚ程度以下であることが望ましい
。Normally, the frequency of the applied AC voltage is 50 Hz or 60 Hz, so if the circuit of the low-pass filter 1 is designed to pass frequency signals of 50 Hz or 60 Hz or less, only pulsating flow components as shown in Fig. 3 can be eliminated. can be detected from the ground wire current ie. Although the frequency of the pulsating flow component to be detected is arbitrary, it is preferably about 5 Hz or less because the higher the frequency, the more disadvantageous it becomes in terms of ground capacity.
この脈流成分の振輻Ａは、水トリー劣化の程度が激しい
程大ぎくなるので、該振幅Ａを求めることにより水トリ
ー劣化の程度を推測することはできる。しかしながら、
ローパスフィルタ１の出力電流は極めて微小なものであ
り、この出力では振幅Ａの大きさの正確な判断は困難で
ある。また脈流成分は、その周波数帯域は狭いとは言え
多数の周波数成分から構成されており、さらに雑音成分
も多く含んでいる。The amplitude A of this pulsating flow component becomes larger as the degree of water tree deterioration becomes more severe, so the degree of water tree deterioration can be estimated by determining the amplitude A. however,
The output current of the low-pass filter 1 is extremely small, and it is difficult to accurately determine the magnitude of the amplitude A using this output. Further, although the frequency band of the pulsating flow component is narrow, it is composed of many frequency components and also contains many noise components.
そこで、当該出力電流を前述した帰還増幅器２で増輻す
ることにより、脈流成分の特定周波数の信号のみを増輻
した第４図に示す如き出力を得る。Therefore, by amplifying the output current using the feedback amplifier 2 described above, an output as shown in FIG. 4 is obtained in which only the signal of a specific frequency of the pulsating flow component is amplified.
この増幅し、増幅された出力では、その振輻Ａ゜は前記
振幅八よりも大きく且つＳ／Ｎ比は良好であり、さらに
単一周波数であるので波形表示装置３による波形ｍｉ′
／Ｑｙ）が容易となり、より正確に水トリー劣化の程度
を知見することができる。In this amplified output, its amplitude A° is larger than the amplitude 8, the S/N ratio is good, and since it has a single frequency, the waveform mi' shown by the waveform display device 3 is
/Qy) becomes easier, and the degree of water tree deterioration can be more accurately determined.
本発明は水トリー劣化を検知しようとするＣＶケーブル
が活線時、非活線時のいずれでも適用可能である。活線
時においては、第１図及び第２図における交流電源Ｅと
して線路に印加されている交流電圧をそのまま利用し、
上述のように脈流成分の振幅の大ざざから水トリー劣化
を知見することができる。また非活線時においては、別
途に交流電源を用意する必要があるが、この場合印加電
圧を可変し得る電源を用い、ケーブルへの印加電圧を零
から次第に増加ざせることにより、より一層正確な劣化
診断が可能となる。この場合の脈流成分の時間変化は、
例えば第５図のグラフ図に示すようになる。なお、横軸
は時間ｔ１縦軸は電流Ｉとしている。前述したように印
加交流電圧の振幅を増加していくと、第５図に示すよう
にある振幅値かＶｏら脈動が認められ、またこの脈動開
始電圧Ｖｏは水トリー劣化が激しい程低くなる。従って
この脈動開始電圧Ｖ。を求めても、水トリー劣化の程度
を推測することが可能となる。The present invention is applicable whether the CV cable whose water tree deterioration is to be detected is live or not. When the line is live, the AC voltage applied to the line is used as it is as the AC power source E in Figures 1 and 2,
As mentioned above, water tree deterioration can be detected from the roughness of the amplitude of the pulsating flow component. Also, when the cable is not live, it is necessary to prepare a separate AC power supply, but in this case, by using a power supply that can vary the applied voltage and gradually increasing the voltage applied to the cable from zero, it is possible to obtain even more accurate results. This enables accurate deterioration diagnosis. In this case, the time change of the pulsating flow component is
For example, it becomes as shown in the graph diagram of FIG. Note that the horizontal axis represents time t and the vertical axis represents current I. As described above, when the amplitude of the applied AC voltage is increased, pulsations are observed from a certain amplitude value Vo as shown in FIG. 5, and the pulsation starting voltage Vo becomes lower as the water tree deterioration becomes more severe. Therefore, this pulsation starting voltage V. It is also possible to estimate the degree of water tree deterioration by determining .
なお、脈動開始電圧Ｖｏを用いて診断を行なう場合の判
定の目安として、第６図に測定対象のケーブルの静電容
量Ｆと脈動開始電圧■０のグラフ図を示す。横軸は静電
容量Ｆを対数目盛で示し、縦軸には脈動開始電圧Ｖｏを
示している。第６図において、水トリー劣化のない健全
なケーブルでは静電容量Ｆと肱動開始電圧Ｖ。を示す状
態点Ｘが概ね実線Ｂ−Ｂ“上に存在するのに対し、水ト
リー劣化が生じたケーブルでは同じ静電容量Ｆでの脈動
開始電圧ＶＯは低下し、状態点Ｘ′は矢印で示すように
実線Ｂ−Ｂ ’から外れることになる。従って実ｌｉＢ
−Ｂ’からの状態点Ｘ゜のずれを基に、水トリー劣化の
程度を定量的に評価することが可能となる。As a guideline for diagnosis when pulsation start voltage Vo is used, FIG. 6 shows a graph of capacitance F of the cable to be measured and pulsation start voltage 0. The horizontal axis shows the capacitance F on a logarithmic scale, and the vertical axis shows the pulsation start voltage Vo. In Fig. 6, a healthy cable with no water tree deterioration has a capacitance F and a bending start voltage V. state point X, which indicates the current state, is approximately on the solid line B-B", whereas in a cable with water tree deterioration, the pulsation starting voltage VO at the same capacitance F decreases, and the state point X' is indicated by the arrow. As shown, it deviates from the solid line B-B'. Therefore, the real liB
It becomes possible to quantitatively evaluate the degree of water tree deterioration based on the deviation of the state point X° from -B'.
さらに、上述した本発明にがかるＣＶケーブルの絶縁劣
化診断装置は、診断すべき全てのケーブルに個々に設け
て据置型として常時監視に用いても良いし、或は運搬が
容易な図示しない筐体に組み入れた可条型とし、複数の
ケーブルに共通して用いても良い。Further, the CV cable insulation deterioration diagnosis device according to the present invention described above may be installed individually on all cables to be diagnosed and used for constant monitoring as a stationary type, or it may be installed in a housing (not shown) that is easy to transport. It may be a flexible type that is incorporated into the cable and used in common for multiple cables.
また、本実施例においては単芯電力ケーブルへの適用の
場合を例示しているが、三芯一括電力ケーブル或は単芯
三線電力ケーブル線路にも同様にして適用可能である。Further, in this embodiment, application to a single-core power cable is exemplified, but the present invention can be similarly applied to a three-core bundled power cable or a single-core three-wire power cable line.
し効果］
以上説明した通りの本発明のＣＶケーブルの絶縁劣化診
断方法及び装置によれば、ケーブル接地線電流中の脈流
成分を検出し、さらにこの脈流成分の中から単一周波数
信号を取り出して増輻した出力信号を時間解析して水ト
リー劣化の程度を知見する方法であり、脈流成分を単に
時間解析する場合に比べ、水トリー劣化の程度の判定基
準となる脈流の振幅を高精度に読み取れ、またＳ／Ｎ比
も良好であるので、より確実な劣化診断が行ない得る。Effect] According to the CV cable insulation deterioration diagnosis method and device of the present invention as described above, a pulsating current component in a cable grounding wire current is detected, and a single frequency signal is further detected from this pulsating current component. This method analyzes the extracted and amplified output signal over time to determine the degree of water tree deterioration.Compared to simply time-analyzing the pulsating flow component, the amplitude of the pulsating flow is a criterion for determining the degree of water tree deterioration. can be read with high precision and has a good S/N ratio, so more reliable deterioration diagnosis can be performed.
さらに、脈流成分の中から特定周波数の信号のみを取り
出して増輻する手段として狭帯域型増幅器、例えば帰還
回路に低周波帯域における選択度が高い並列Ｔ型ＣＲ回
路を用いた帰還増幅器を使用することにより、脈流成分
を高選択度で増輻することができ、Ｓ／Ｎ比を向上きせ
ることかできるので、より確実で正確な劣化診断を行な
うことができる。Furthermore, as a means of extracting and amplifying only the signal of a specific frequency from the pulsating flow components, a narrowband amplifier is used, for example, a feedback amplifier using a parallel T-type CR circuit with high selectivity in the low frequency band as a feedback circuit. By doing so, the pulsating flow component can be increased with high selectivity and the S/N ratio can be improved, so that more reliable and accurate deterioration diagnosis can be performed.
【図面の簡単な説明】
第１図は本発明のＣＶケーブルの劣化診断方法を実施す
るための一例を示すブロック図、第２図は第１図に示す
ブロック図の具体的な回路構成の一例を示す回路構成図
、第３図はローパスフィルタの出力の時間変化を示すグ
ラフ図、第４図は帰還増幅器の出力の時間変化を示すグ
ラフ図、第５図は停止線路の診断における表示波形のグ
ラフ図、第６図は停止線路の診断基準のグラフ図をそれ
ぞれ表している。
１・・・ローパスフィルタ、１０・・・電流検出装置、
２・・・増幅器、２０・・・並列Ｔ型ＣＲ回路、３・・
・波形表示装置、４・・・供試ＣＶケーブル、４１・・
・導体、４２・・・絶縁体、４３・・・遮蔽層、ｉｅ・
・・接地線電流、Ｅ・・・交流電源、ＣＴ・・・変流器[Brief Description of the Drawings] Fig. 1 is a block diagram showing an example of implementing the CV cable deterioration diagnosis method of the present invention, and Fig. 2 is an example of a specific circuit configuration of the block diagram shown in Fig. 1. 3 is a graph showing the time change in the output of the low-pass filter, FIG. 4 is a graph showing the time change in the output of the feedback amplifier, and FIG. 5 is a graph showing the time change in the output of the feedback amplifier. The graph diagram and FIG. 6 each represent a graphic diagram of the diagnostic criteria for a stopped line. 1...Low pass filter, 10...Current detection device,
2...Amplifier, 20...Parallel T-type CR circuit, 3...
・Waveform display device, 4... Test CV cable, 41...
・Conductor, 42... Insulator, 43... Shielding layer, ie・
...Grounding wire current, E...AC power supply, CT...current transformer
Claims (3)
の接地線より接地線電流を検出し、該接地線電流より脈
流成分を検出し、さらに該脈流成分の中から特定周波数
の信号のみを取り出してこれを増幅し、増幅された特定
周波数の脈流成分の時間解析を行なうことにより、ケー
ブル絶縁体の劣化の程度を検知することを特徴とするＣ
Ｖケーブルの絶縁劣化診断方法。(1) Apply AC voltage to the power cable to be measured, detect the grounding line current from the grounding line, detect the pulsating current component from the grounding line current, and then detect a signal of a specific frequency from the pulsating current component. The degree of deterioration of the cable insulation is detected by extracting and amplifying the pulsating flow component of the amplified specific frequency, and performing time analysis of the amplified pulsating flow component of a specific frequency.
Method for diagnosing insulation deterioration of V cable.
切断せずに行うことを特徴とする特許請求の範囲第（１
）項記載のＣＶケーブルの絶縁劣化診断方法。(2) The detection of the grounding wire current from the grounding wire is performed without cutting the grounding wire.
) The method for diagnosing insulation deterioration of CV cables described in section 2.
する接地線より接地線電流を検出する電流検出装置と、
検出した接地線電流より脈流成分を取り出すローパスフ
ィルタと、該ローパスフィルタの出力に接続される狭帯
域増幅器と、該狭帯域増幅器の出力信号を時間軸に表示
する波形表示手段とを備えたことを特徴とするＣＶケー
ブルの絶縁劣化診断装置。(3) a current detection device that detects a ground line current from a ground line connecting between the shielding layer of the CV cable and a potential reference;
A low-pass filter for extracting a ripple component from the detected ground line current, a narrow-band amplifier connected to the output of the low-pass filter, and a waveform display means for displaying the output signal of the narrow-band amplifier on a time axis. A CV cable insulation deterioration diagnostic device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32564889A JP2832737B2 (en) | 1989-11-17 | 1989-12-15 | Method and apparatus for diagnosing insulation deterioration of CV cable |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29895389 | 1989-11-17 | ||
| JP1-298953 | 1989-11-17 | ||
| JP32564889A JP2832737B2 (en) | 1989-11-17 | 1989-12-15 | Method and apparatus for diagnosing insulation deterioration of CV cable |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03218481A true JPH03218481A (en) | 1991-09-26 |
| JP2832737B2 JP2832737B2 (en) | 1998-12-09 |
Family
ID=26561722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32564889A Expired - Fee Related JP2832737B2 (en) | 1989-11-17 | 1989-12-15 | Method and apparatus for diagnosing insulation deterioration of CV cable |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2832737B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115453273A (en) * | 2022-06-30 | 2022-12-09 | 中广核(东至)新能源有限公司 | Power cable insulation monitoring device |
-
1989
- 1989-12-15 JP JP32564889A patent/JP2832737B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115453273A (en) * | 2022-06-30 | 2022-12-09 | 中广核(东至)新能源有限公司 | Power cable insulation monitoring device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2832737B2 (en) | 1998-12-09 |
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