JPH03170076A - Partial discharge measuring method - Google Patents
Partial discharge measuring methodInfo
- Publication number
- JPH03170076A JPH03170076A JP30974389A JP30974389A JPH03170076A JP H03170076 A JPH03170076 A JP H03170076A JP 30974389 A JP30974389 A JP 30974389A JP 30974389 A JP30974389 A JP 30974389A JP H03170076 A JPH03170076 A JP H03170076A
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- partial discharge
- detection
- ratio
- noise
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- 238000000034 method Methods 0.000 title claims description 14
- 238000001228 spectrum Methods 0.000 claims abstract description 22
- 239000004020 conductor Substances 0.000 claims abstract description 8
- 238000000691 measurement method Methods 0.000 claims description 9
- 238000001514 detection method Methods 0.000 abstract description 34
- 238000005259 measurement Methods 0.000 abstract description 23
- 230000035945 sensitivity Effects 0.000 abstract description 14
- 239000003990 capacitor Substances 0.000 abstract description 5
- 230000008878 coupling Effects 0.000 abstract description 5
- 238000010168 coupling process Methods 0.000 abstract description 5
- 238000005859 coupling reaction Methods 0.000 abstract description 5
- 238000007599 discharging Methods 0.000 abstract 1
- 230000005611 electricity Effects 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 6
- 239000002184 metal Substances 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 239000012212 insulator Substances 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000012790 confirmation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
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Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は高電圧が課電される電力ケーブル等の絶縁体の
劣化を診断するための部分放電測定方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a partial discharge measuring method for diagnosing deterioration of an insulator such as a power cable to which a high voltage is applied.
従来多く用いられた部分放電測定方法は、第４図（Ａ）
に示すように、電力ケーブル１（便宜上静電容量Ｃ８と
して示した）の終端接続部付近で、結合コンデンサ３と
アースとの間に検出インピーダンス４を挿入するか、第
４図（Ｂ）に示すように結合コンデンサ３を直接接地し
、電力ケーブル１のシースとアースの間に検出インピー
ダンス４を挿入して、検出インピーダンス４の両端から
高周波戒分を取り出して測定装置５で検出する方法が用
いられている。The partial discharge measurement method that has been widely used in the past is shown in Figure 4 (A).
As shown in Fig. 4(B), a detection impedance 4 is inserted between the coupling capacitor 3 and ground near the terminal connection of the power cable 1 (shown as capacitance C8 for convenience), or as shown in Fig. 4(B). A method is used in which the coupling capacitor 3 is directly grounded, the detection impedance 4 is inserted between the sheath of the power cable 1 and the ground, and the high frequency command is taken out from both ends of the detection impedance 4 and detected by the measuring device 5. ing.
第４図（Ａ）または（Ｂ）の構成において、高電圧課電
端子２に交流高電圧を課電し、電力ケーブル１により構
威される送電線路を活線状態にした状態で、電力ケーブ
ル１の絶縁体に部分放電が生じると、検出インピーダン
ス４の両端に電位差が発生する．この電位差に基づいて
絶縁体中の部分放電を測定する．
このような回路を用いて部分放電を測定する方法は、下
記の三種に大別される。In the configuration shown in FIG. 4 (A) or (B), the power cable is When a partial discharge occurs in the insulator 1, a potential difference occurs across the detection impedance 4. Partial discharge in the insulator is measured based on this potential difference. Methods for measuring partial discharge using such a circuit can be broadly classified into the following three types.
（１）低周波測定法（測定周波数１５ｋＨｚないし１５
０ｋＨｚ）
（２）広帯域測定法（測定周波数数ｋＨｚないし数ＭＨ
ｚ）
（３）同調式測定法（測定周波数１００ｋＨｚないし数
ＭＨｚ）
同調式測定法の場合には、一般に同調周波数を固定され
た数種類の周波数からスイッチで選択して用いるもの、
あるいは同調周波数を掃引するものがある。(1) Low frequency measurement method (measurement frequency 15kHz to 15kHz)
(2) Wideband measurement method (measurement frequency from several kHz to several MHz)
(3) Tuned measurement method (measurement frequency 100 kHz to several MHz) In the case of the tuned measurement method, the tuning frequency is generally selected from several fixed frequencies using a switch;
Alternatively, there is one that sweeps the tuning frequency.
しかし上記の同調式測定法の場合、同調周波数を固定す
る方式では、測定に利用する周波数において大きなノイ
ズが認められる場合にも、その周波数で測定するはかな
く、部分放電測定の高い感度を得ることが困難であった
．
特に長尺ケーブルの終端接続部から遠い場所、例えば中
間接続部等で発生した部分放電パルスは、ケーブルのイ
ンダクタンス等のため検出部に達するまでに減衰を受け
るほか、外部からのノイズの影響も大きくなり、Ｓ／Ｎ
比が低くなる。However, in the case of the above-mentioned tuning measurement method, with the method of fixing the tuning frequency, even if there is large noise at the frequency used for measurement, it is difficult to measure at that frequency, making it impossible to obtain high sensitivity in partial discharge measurement. It was difficult. In particular, partial discharge pulses that occur far from the end connection of a long cable, such as an intermediate connection, are attenuated by cable inductance before reaching the detection unit, and are also greatly affected by external noise. Nari, S/N
ratio becomes lower.
検出されるノイズは主に、商用交流電力ケーブルの送電
電流に含まれる高調波戒分、サイリスク等の機器から生
ずるパルス、放送等の空気中の電磁波に由来するもの、
大地を流れるノイズ性電流による大地電位の浮動に起因
するもの等から或ると見られる。The detected noise mainly originates from harmonics contained in the transmission current of commercial AC power cables, pulses generated from devices such as Cyrisk, electromagnetic waves in the air such as broadcasting, etc.
This is thought to be caused by the floating of the ground potential due to the noisy current flowing through the ground.
一方同調周波数を掃引する方式では、特定のノイズ周波
数を避けたとしても、後述する理由でその周波数におい
て信号レベルも低くなると所定のＳ／Ｎ比を得ることが
できない。即ち、部分放電測定におけるＳ／．Ｎ比の周
波数による変化は極めて複雑で、送配電系の構造、部分
放電の発生個所、測定場所、測定時期等によって変わる
ので、予測することは到底不可能であり、高いＳ／Ｎ比
を得ることが難しかった。On the other hand, in the method of sweeping the tuning frequency, even if a specific noise frequency is avoided, a predetermined S/N ratio cannot be obtained if the signal level also becomes low at that frequency for reasons described later. That is, S/. in partial discharge measurement. Changes in the N ratio with frequency are extremely complex and vary depending on the structure of the power transmission and distribution system, the location where partial discharge occurs, the measurement location, the measurement time, etc., so it is completely impossible to predict, and it is impossible to obtain a high S/N ratio. That was difficult.
従って本発明の目的は、電力ケーブル、特に長尺ケーブ
ルにおける部分放電を、高感度、即ち高いＳ／Ｎ比で検
出できる部分放電測定方法を提供することである。Therefore, an object of the present invention is to provide a partial discharge measuring method that can detect partial discharges in power cables, particularly long cables, with high sensitivity, that is, with a high S/N ratio.
上記目的を達或するため本発明では、電力ケーブル線路
のノイズ性信号に対する周波数スペクトルを求め、一方
、検出感度の較正のため較正パルスをケーブルに注入し
て出力を測定し、ケーブルに注入した較正パルスの検出
出力（Ｓ＋Ｎに相当）とノイズスペクトル（Ｎに相当）
を比較して、Ｓ／Ｎ比の高い周波数を見出し、この周波
数で部分放電測定を行うようにした．
較正パルスおよびノイズの周波数スペクトルは周波数掃
引型のスペクトルアナライザを用いて求めることができ
る。ノイズ性信号の周波数スペクトル測定は、較正パル
スの周波数スペクトル測定の前でも後でもよい．
較正パルスは、電力ケーブルの導体とシース間に直接注
入してもよいが、ケープルシースあるいは絶縁接続箱等
において隔離されたシース間に注入してもよい．較正パ
ルスをシースヘ注入する場合は、活線状態でも可能であ
り、安全性の点でも有利である．
前述のようにＳ／Ｎ比の周波数依存性は場所や時期によ
り一定でないので、測定周波数を連続可変にしておくこ
とが好ましい。商用交流電力ケーブルの送電電流に含ま
れる高調波、サイリスクから生ずるパルス或分等の介入
を避けるため、測定周波数は１０ｋＪ以上から選択する
のが好ましい。周波数範囲の上限は特にないが、通常１
００ＭＨｚ程度である。In order to achieve the above object, the present invention obtains a frequency spectrum for a noisy signal on a power cable line, and on the other hand, injects a calibration pulse into the cable to measure the output in order to calibrate the detection sensitivity. Pulse detection output (equivalent to S+N) and noise spectrum (equivalent to N)
By comparing the two frequencies, we found a frequency with a high S/N ratio, and decided to perform partial discharge measurements at this frequency. The frequency spectra of the calibration pulse and noise can be determined using a frequency sweep type spectrum analyzer. The frequency spectrum measurement of the noisy signal may be performed before or after the frequency spectrum measurement of the calibration pulse. The calibration pulse may be injected directly between the conductor and sheath of the power cable, or it may be injected between isolated sheaths such as in a cable sheath or insulated junction box. Injecting the calibration pulse into the sheath can be done even when the wire is live, which is advantageous in terms of safety. As mentioned above, the frequency dependence of the S/N ratio is not constant depending on location or time, so it is preferable to make the measurement frequency continuously variable. In order to avoid the interference of harmonics contained in the transmission current of the commercial AC power cable, pulses generated from sirisk, etc., it is preferable to select the measurement frequency from 10 kJ or more. There is no upper limit to the frequency range, but it is usually 1
It is about 00MHz.
本発明の部分放電測定方法では、部分放電が絶縁層で発
生したとき、内部導体を往路、外部半電導層および外側
金属シース、場合によりさらにワイヤシールドを帰路と
するパルス電流が流れる。In the partial discharge measuring method of the present invention, when a partial discharge occurs in the insulating layer, a pulse current flows through the inner conductor, the outer semiconducting layer and the outer metal sheath, and optionally the wire shield as a return path.
このパルス電流により、検出インピーダンスの両端に電
位差を生ずる。本発明の方法では、較正パルスによる検
出感度の較正でＳ／Ｎ比がなるべく高くなる測定周波数
を選択し、その周波数において部分放電パルスを測定す
る。固定された周波数で測定する測定方法あるいは信号
レベルの周波数依存性を考慮しない測定方法と異なり、
測定条件に応じ最も高いＳ／Ｎ比が得られる測定周波数
を選んで用いることができるから、Ｓ／Ｎ比の高い部分
放電測定ができる。This pulse current generates a potential difference across the detection impedance. In the method of the present invention, a measurement frequency at which the S/N ratio is as high as possible is selected by calibrating the detection sensitivity using a calibration pulse, and a partial discharge pulse is measured at that frequency. Unlike measurement methods that measure at a fixed frequency or that do not consider the frequency dependence of the signal level,
Since the measurement frequency that provides the highest S/N ratio can be selected and used depending on the measurement conditions, partial discharge measurement with a high S/N ratio can be performed.
以下、本発明の実施例を説明する前に本発明者が確認し
たノイズの周波数依存性を説明する。Hereinafter, before describing embodiments of the present invention, the frequency dependence of noise confirmed by the inventor will be explained.
長さ１０ｍの６６ｋＶ用ＣＶケーブルを供試ケーブルと
し、第４図（Ｂ）に示した回路で測定装置５として周波
数掃引型信号強度測定器を接続して、ケーブル１に課電
せずノイズのみの状態で検出されるパルスの周波数スペ
クトルを求めると、第５図（Ａ）ないし（Ｃ）に示す如
くであった。A 66 kV CV cable with a length of 10 m was used as the test cable, and a frequency sweep type signal strength measuring instrument was connected as the measuring device 5 using the circuit shown in Fig. 4 (B) to measure only noise without applying power to the cable 1. The frequency spectra of the pulses detected under these conditions were determined as shown in FIGS. 5(A) to 5(C).
第５図（Ａ）は周波数１０ＭＨｚまでの範囲でのノイズ
の周波数スペクトルである。４ＭＨｚ付近で特にノイズ
のレベルが高いことを示している。FIG. 5(A) is a frequency spectrum of noise in a frequency range up to 10 MHz. This shows that the noise level is particularly high near 4 MHz.
第５図（Ｂ）は３，ＯＭＨｚから５．０ＭＨｚの範囲を
拡大して示したもの、第５図（Ｃ）はさらに３．８ＭＨ
ｚから４．２ＭＨＺの範囲だけを拡大して示したもので
、ノイズレベルが大きな周波数依存性を有していること
がわかる。第５図（Ｃ）から明らかなように、４ＭＨｚ
付近、特に３。８２ＭＨｚ付近と３．９２ないし３．９
５ＭＨｚでノイズレベルが高く、これに比し３．８８Ｍ
｝ｌｚおよび４．０ないし４．ｌ５ＭＨｚにノイズレベ
ルがかなり低い所がある。Figure 5 (B) is an enlarged view of the range from 3.0 MHz to 5.0 MHz, and Figure 5 (C) is an expanded view of the range from 3.8 MHz.
z to 4.2 MHz, showing that the noise level has a large frequency dependence. As is clear from Figure 5(C), 4MHz
around 3.82MHz and 3.92 to 3.9
The noise level is high at 5MHz, compared to 3.88M.
}lz and 4.0 to 4. There is a place at 15MHz where the noise level is quite low.
３．８８ＭＨｚでのノイズレベルは３．８２ＭＨｚに比
し約３５ｄＢも低い。このようにノイズは輝線スペクト
ルを示す場合がかなり多く、しかもその近傍にしばしば
ノイズレベルのかなり低い領域が存在する。The noise level at 3.88 MHz is about 35 dB lower than that at 3.82 MHz. In this way, noise often exhibits an emission line spectrum, and moreover, there are often areas in the vicinity of which the noise level is considerably low.
ノイズの周波数分布だけでなく、部分放電パルスの信号
検出感度も複雑な周波数分布を有する。Not only the frequency distribution of noise but also the signal detection sensitivity of partial discharge pulses has a complicated frequency distribution.
ノイズ、部分放電パルスいずれについても、次のような
要因が考えられる。The following factors can be considered for both noise and partial discharge pulses.
（１）電力ケーブルの回路構成は複雑で、多くのし、Ｃ
成分等があり、これらによる種々の周波数での共振、反
共振が生じ、信号周波数によりその振幅が複雑に変化す
る。(1) The circuit configuration of power cables is complex, and there are many
These components cause resonance and anti-resonance at various frequencies, and the amplitude changes in a complex manner depending on the signal frequency.
（２）パルスが複雑な電力ケーブル線路上をミスマッチ
ングの状態で往復反射されながら伝播するため、定在波
が生じ、検出地点が定在波の谷に当たると低い検出感度
を与え、腹に当たると高い検出感度を与える。(2) Since the pulse propagates on the complicated power cable line while being reflected back and forth in a state of mismatching, a standing wave is generated, and when the detection point hits the trough of the standing wave, the detection sensitivity is low, and when the detection point hits the antinode, it gives a low detection sensitivity. Gives high detection sensitivity.
以上の確認結果に基づいて本発明の第一の実施例を説明
する。A first embodiment of the present invention will be described based on the above confirmation results.
本発明に係わる部分放電検出方法に用いた回路を第１図
に示す。第１図の回路で高電圧課電端子２に接続された
高圧導体とアースの間に結合コンデンサ３と検出インピ
ーダンス４が接続され、検出インピーダンス４に並列に
、測定装置５が接続されている。測定装置５はスペクト
ルアナライザおよびパルス計数装置から或る。供試ケー
ブル１の高圧導体とシース間には、パルス発生器６を接
続した。第１図で供試ケーブル１は静電容１ｃ．として
表示した。供試ケーブル１は長さ１０ｍの６６ｋＶ用Ｃ
Ｖケーブルで、高電圧課電端子２から高電圧を課電され
る。FIG. 1 shows a circuit used in the partial discharge detection method according to the present invention. In the circuit shown in FIG. 1, a coupling capacitor 3 and a detection impedance 4 are connected between a high voltage conductor connected to a high voltage charging terminal 2 and the ground, and a measuring device 5 is connected in parallel to the detection impedance 4. The measuring device 5 consists of a spectrum analyzer and a pulse counter. A pulse generator 6 was connected between the high voltage conductor and sheath of the test cable 1. In FIG. 1, the test cable 1 has a capacitance of 1c. It was displayed as Test cable 1 is 66kV C with a length of 10m.
A high voltage is applied from the high voltage charging terminal 2 through the V cable.
ケーブルｌに課電せず、パルス発生器６も作動させない
、つまりノイズのみの状態で、この回路で検出信号の周
波数スペクトルを求めた。その結果を第２図（Ａ）に示
す。The frequency spectrum of the detection signal was determined using this circuit with no voltage applied to the cable l and without operating the pulse generator 6, that is, with only noise present. The results are shown in FIG. 2(A).
次いで第１図に示す回路で供試ケーブル１の導体側とシ
ース間に接続したパルス発生器６を作動させ、パルス発
生器６から１００ｐＣ（ビコクーロン）の較正パルスを
注入する。その状態で、測定装置５のスペクトルアナラ
イザを用いて検出パルスの周波数依存性を求めた。その
結果を第２図（Ｂ）に示す。Next, the pulse generator 6 connected between the conductor side of the test cable 1 and the sheath is activated using the circuit shown in FIG. 1, and a calibration pulse of 100 pC (bicocoulombs) is injected from the pulse generator 6. In this state, the frequency dependence of the detected pulse was determined using the spectrum analyzer of the measuring device 5. The results are shown in FIG. 2(B).
第２図（Ａ）と第２図（Ｂ）とを比較すると、約３ＭＨ
ｚ未満では較正パルス注入時でも注入パルスの寄与は小
さく、ほとんどがノイズであるが、３．５ＭＨｚ以上で
は信号レベルが−５０ｄＢ付近のレベルを保つのに対し
てノイズは４ＭＨｚ近辺を除き−６０ｄＢ以下に下がり
、特に４．５ＭＨｚから５．５ＭＨｚの間でノイズは顕
著に低下し、それより高い周波数では−７０ｄＢ以下と
なっている。結局４．８ＭＨｚから１０ＭＨｚでＳ／Ｎ
比が高くなることがわかる。特にノイズレベルが低いの
は５．５ ＭＨ ｚ， ６．２ＭＨ ｚ， ９．２ＭＨ
ｚであり、これらの周波数ではＳ／Ｎ比も高い。Comparing Figure 2 (A) and Figure 2 (B), approximately 3MH
Below 3.5 MHz, the contribution of the injection pulse is small even when injecting a calibration pulse, and most of it is noise. However, at frequencies above 3.5 MHz, the signal level remains around -50 dB, while the noise is below -60 dB except around 4 MHz. In particular, the noise drops significantly between 4.5 MHz and 5.5 MHz, and is below -70 dB at higher frequencies. In the end, the S/N is from 4.8MHz to 10MHz.
It can be seen that the ratio becomes higher. Particularly low noise levels are 5.5 MHz, 6.2 MHz, and 9.2 MHz.
z, and the S/N ratio is also high at these frequencies.
例えば５．５ＭＨｚではノイズレベルは−８２ｄＢ，信
号レベルは約−４８ｄＢであり、従ってＳ／Ｎ比は３４
ｄＢであった（検出限界は従って１００ｐｃの１／５０
，すなわち２ｐＣに相当する）．４．８ＭＨｚから１０
ＭＨｚの範囲であっても、８．４ＭＨｚで測定するとノ
イズレベルは約−７０ｄＢ、信号レベルは−４８ｄＢで
あり、従って約２２ｄＢのＳ／Ｎ比しか得られない。こ
れは、測定周波数の少しの差でもＳ／Ｎ比の大きな差異
をもたらすことを示している．
第２図（Ａ）に見られるように、周波数３．０ないし３
．２ＭＨ！ではノイズレベルが比較的低く（約−６６ｄ
Ｂ）、４．５ＭＨｚ以上のそれに近い．が、この周波数
では信号レベルが−５８ｄＢ程度に低下しており、僅か
８ｄＢ程度のＳ／Ｎ比しか得られない。つまり４．８Ｍ
Ｈｚ以上で測定した場合に比しＳ／Ｎ比は２０ｄＢ以上
低い。For example, at 5.5 MHz, the noise level is -82 dB and the signal level is about -48 dB, so the S/N ratio is 34.
dB (the detection limit is therefore 1/50 of 100pc
, which corresponds to 2pC). 4.8MHz to 10
Even in the MHz range, when measured at 8.4 MHz, the noise level is about -70 dB and the signal level is -48 dB, so an S/N ratio of only about 22 dB can be obtained. This shows that even a small difference in measurement frequency results in a large difference in S/N ratio. As seen in Figure 2(A), the frequency 3.0 to 3
．． 2MH! The noise level is relatively low (approximately -66d
B), close to that of 4.5MHz or higher. However, at this frequency, the signal level drops to about -58 dB, and an S/N ratio of only about 8 dB can be obtained. That is 4.8M
The S/N ratio is 20 dB or more lower than when measured at Hz or higher.
ここで従来の低周波式測定を試みた。低周波用の検出イ
ンピーダンスとバンドパスフィルタを用い、増幅周波数
帯域を１０ｋ｝｛ｚないし１５０ｋＨｚおよび１０ｋＨ
ｚないしｌｏ００ｋＨｚの範囲で連続的に変化させて、
Ｓ／Ｎ比を測定したところ、検出限界はせいぜい約７０
ｐＣであった。Here, we attempted conventional low-frequency measurement. Using a detection impedance for low frequencies and a bandpass filter, the amplification frequency band is 10kHz to 150kHz and 10kHz.
Continuously change in the range of z to lo00kHz,
When I measured the S/N ratio, the detection limit was about 70 at most.
It was pC.
これにより、低周波法ではあまり感度が高くないことが
確認された。This confirmed that the sensitivity of the low-frequency method is not very high.
以上の測定結果に基づき、５−５ＭＨｚ，６。２ＭＨｚ
，９．２ＭＨｚのうちから５．５ＭＨＺを選んで、測定
装置５のパルス計数装置を用いて活線状態での電力ケー
ブルの部分放電測定を行った。Based on the above measurement results, 5-5MHz, 6.2MHz
, 9.2 MHz, and the pulse counting device of the measuring device 5 was used to measure the partial discharge of the power cable in the live line state.
従来の同調式部分放電測定器（■日本計測器製造所製）
を用いて、部分放電測定を行った。Conventional tunable partial discharge measuring device (manufactured by Nippon Keiki Seisakusho)
Partial discharge measurements were performed using
この測定器の使用周波数は４００ｋＨｚである。The operating frequency of this measuring instrument is 400kHz.
Ｓ／Ｎ比は１０ｄＢ、検出限界は３０ｐＣであった．こ
れは、本発明の方法を用い５．５ＭＨｚを選択して測定
した場合の検出限界（２ｐＣ）の１５低である（感度で
１／１５）．
〔実施例２〕
実施例ｌにおいてはパルス発生器６を供試ケーブルｌの
内部導体とシース間に接続したが、本実施例では第３図
に示すように、ケーブルｌａ，ｌｂ−ｔ−接続する絶縁
接続部７の各絶縁シースの外側に貼りつけた金属箔電極
８ａと８ｂの間にパルス発生器６を接続した．そして、
検出インピーダンス４および測定装置５をケーブルｌａ
側のシース７ａとケーブルｌｂ側のシース７ｂの間に接
続した。パルス発生器６および測定装置５の接続はケー
ブルの無謀電状態で行った．
実施例１と同様、パルス発生器６を作動させないでノイ
ズの周波数スペクトルを測定した後、パルス発生器６か
ら較正パルスを注入し、ノイズと較正パルスの周波数ス
ペクトルを比較して、Ｓ／Ｎ比の最も高い周波数を見つ
けた．次に、パルス発生器６の作動を停止させ、活線状
態のケーブルの部分放電を、上で選択した周波数５．５
ＭＨｚで測定した．その結果、実施例１にほぼ等しいＳ
／Ｎ比で部分放電の測定を行うことができた。なお、金
属箔電極８ａ，８ｂの取り付けおよびパルス発生器６の
接続はケーブルの活線状態で行ってもよい。The S/N ratio was 10 dB and the detection limit was 30 pC. This is 15 times lower than the detection limit (2 pC) when 5.5 MHz is selected and measured using the method of the present invention (1/15 in sensitivity). [Example 2] In Example 1, the pulse generator 6 was connected between the internal conductor and sheath of the test cable 1, but in this example, as shown in FIG. A pulse generator 6 was connected between metal foil electrodes 8a and 8b attached to the outside of each insulating sheath of the insulating connection part 7. and,
Detection impedance 4 and measuring device 5 are connected to cable la
It was connected between the side sheath 7a and the cable lb side sheath 7b. The connection between the pulse generator 6 and the measuring device 5 was made with the cables in a non-conductive state. As in Example 1, after measuring the frequency spectrum of noise without operating the pulse generator 6, a calibration pulse is injected from the pulse generator 6, and the frequency spectra of the noise and calibration pulse are compared to determine the S/N ratio. I found the highest frequency of . Next, the pulse generator 6 is deactivated and the partial discharge of the live cable is caused to occur at the frequency 5.5 selected above.
Measured in MHz. As a result, S
/N ratio was able to measure partial discharge. Note that the attachment of the metal foil electrodes 8a, 8b and the connection of the pulse generator 6 may be performed while the cable is in a live state.
本発明の部分放電測定方法によると、電力ケーブルにお
ける部分放電を、高感度で検出できる。According to the partial discharge measuring method of the present invention, partial discharge in a power cable can be detected with high sensitivity.
特に、長尺ケーブルの場合に有用である。This is particularly useful for long cables.
本発明によると、従来の固定された周波数で、あるいは
単にノイズの大きい周波数を避けて測定する方法では得
られない高いＳ／Ｎ比、すなわち検出感度を、得ること
ができる。According to the present invention, it is possible to obtain a high S/N ratio, that is, detection sensitivity, which cannot be obtained with the conventional method of measuring using a fixed frequency or simply avoiding frequencies with large noise.
第１図は本発明の部分放電検出方法の一実施例に用いた
回路を示す説明図、第２図（Ａ）は測定されたノイズの
みの周波数スペクトルを示すグラフ、第２図（Ｂ）は較
正パルスを注入したとき測定された信号の周波数スペク
トルを示すグラフ、第３図は本発明の他の実施例を示す
説明図、第４図（Ａ）および（Ｂ）は従来の部分放電測
定方法を示す説明図、第５図（Ａ）ないし（Ｃ）はノズ
の周波数スペクトルを示すグラフである。
符号の説明
１，ｌａ，Ｉｂ・・−・・・・・・・・電力ケーブル２
−・一・−・・・高電圧課電端子
３−−−−−−−−−一結合コンデンサ４−−−−一・
・−・検出インピーダンス５−・−・−・・・・測定装
置
６−−−−−−−−・・−・パルス発生器７−・−・一
絶縁接続部
７ａ，７ｂ・−・・一絶縁接続部シース８ａ，８ｂ−・
・−・・・金属箔電極
イFig. 1 is an explanatory diagram showing a circuit used in an embodiment of the partial discharge detection method of the present invention, Fig. 2 (A) is a graph showing the frequency spectrum of only the measured noise, and Fig. 2 (B) is a graph showing the frequency spectrum of only the measured noise. A graph showing the frequency spectrum of the signal measured when a calibration pulse was injected, FIG. 3 is an explanatory diagram showing another embodiment of the present invention, and FIGS. 4 (A) and (B) are the conventional partial discharge measurement method. 5A to 5C are graphs showing the frequency spectrum of the nozzle. Explanation of symbols 1, la, Ib... Power cable 2
−・1・−・High voltage charging terminal 3−−−−−−−−−1 coupling capacitor 4−−−−1・
・−・Detection impedance 5−・−・−・・Measurement device 6−−−−−−−・・・Pulse generator 7−・−・1 Insulated connection parts 7a, 7b・・・・1 Insulating connection part sheath 8a, 8b-・
・−・・・Metal foil electrode
Claims (3)
、較正パルスを前記電力ケーブル線路に注入したときに
検出される出力との、それぞれの周波数スペクトルを求
め、前記周波数スペクトルからＳ／Ｎ比の周波数依存性
を求め、高いＳ／Ｎ比を有する周波数で部分放電パルス
を測定する部分放電測定方法。(1) Obtain the respective frequency spectra of the noisy output detected from the power cable line and the output detected when a calibration pulse is injected into the power cable line, and calculate the S/N ratio from the frequency spectrum. A partial discharge measurement method that determines frequency dependence and measures partial discharge pulses at a frequency that has a high S/N ratio.
の間に注入する請求項第１項の部分放電測定方法。(2) The method for measuring partial discharge according to claim 1, wherein the calibration pulse is injected between a conductor and a sheath of a power cable.
たシース間に注入する請求項第１項の部分放電測定方法
。(3) The partial discharge measuring method according to claim 1, wherein the calibration pulse is injected between mutually separated sheaths such as an insulating connection part.
Priority Applications (22)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1309743A JPH068846B2 (en) | 1989-11-29 | 1989-11-29 | Partial discharge measurement method |
| NO900431A NO302494B1 (en) | 1989-10-25 | 1990-01-30 | A method for detecting a partial discharge in an electrical power cable insulation |
| CA002008898A CA2008898C (en) | 1989-10-25 | 1990-01-30 | Method for detecting partial discharge in an insulation of an electric power apparatus |
| EP97111472A EP0806677A1 (en) | 1989-10-25 | 1990-01-31 | Method for detecting partial discharge |
| EP90101895A EP0424598B1 (en) | 1989-10-25 | 1990-01-31 | Method for detecting partial discharge in an insulation of an electric power cable |
| DE69026186T DE69026186T2 (en) | 1989-10-25 | 1990-01-31 | Method for determining partial discharges in the insulation of an electrical power cable |
| DE69033263T DE69033263T2 (en) | 1989-10-25 | 1990-01-31 | Method for comparing frequency spectra |
| DE69032763T DE69032763T2 (en) | 1989-10-25 | 1990-01-31 | Use of a magnetic core for measuring partial discharges |
| EP94111232A EP0628829B1 (en) | 1989-10-25 | 1990-01-31 | Use of magnetic core to measure partial discharge |
| EP03000561A EP1310803A3 (en) | 1989-10-25 | 1990-01-31 | Method for detecting partial discharge |
| EP94111230A EP0629866B1 (en) | 1989-10-25 | 1990-01-31 | Method for locating faults in an electric power cable line |
| EP94111231A EP0636890B1 (en) | 1989-10-25 | 1990-01-31 | Method for comparing frequency spectrums |
| DE69033279T DE69033279T2 (en) | 1989-10-25 | 1990-01-31 | Method for measuring partial discharges in a wire with a detection electrode |
| DE69032808T DE69032808T2 (en) | 1989-10-25 | 1990-01-31 | Procedure for locating faults in electrical power cables |
| EP97111457A EP0806676B1 (en) | 1989-10-25 | 1990-01-31 | Use of detecting electrode to measure partial discharge in a wire |
| US07/784,728 US5323117A (en) | 1989-10-25 | 1991-10-28 | Method for detecting partial discharge in an insulation of an electric power apparatus |
| US08/163,572 US5469067A (en) | 1989-10-25 | 1993-12-08 | Detecting partial discharge using a detection coil and analysis of output signal and noise frequency spectrums |
| NO963527A NO303304B1 (en) | 1989-10-25 | 1996-08-23 | A method of detecting a partial discharge in an insulation of an electric power cable or similar |
| NO963530A NO304126B1 (en) | 1989-10-25 | 1996-08-23 | A method for detecting partial discharge in an insulation for electrical devices |
| NO963529A NO304761B1 (en) | 1989-10-25 | 1996-08-23 | A method of detecting partial discharge in an insulation of an electr |
| NO963528A NO301673B1 (en) | 1989-10-25 | 1996-08-23 | Method for detecting partial discharge in an insulation of an electrical device |
| NO974684A NO309881B1 (en) | 1989-10-25 | 1997-10-10 | Method for Detecting Partial Discharge in Power Cables Coupled by Insulation Joints |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1309743A JPH068846B2 (en) | 1989-11-29 | 1989-11-29 | Partial discharge measurement method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03170076A true JPH03170076A (en) | 1991-07-23 |
| JPH068846B2 JPH068846B2 (en) | 1994-02-02 |
Family
ID=17996765
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1309743A Expired - Lifetime JPH068846B2 (en) | 1989-10-25 | 1989-11-29 | Partial discharge measurement method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH068846B2 (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6140571A (en) * | 1984-07-31 | 1986-02-26 | Showa Electric Wire & Cable Co Ltd | Partial dischrge measurement of hot cable |
-
1989
- 1989-11-29 JP JP1309743A patent/JPH068846B2/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6140571A (en) * | 1984-07-31 | 1986-02-26 | Showa Electric Wire & Cable Co Ltd | Partial dischrge measurement of hot cable |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH068846B2 (en) | 1994-02-02 |
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