JPH068846B2 - Partial discharge measurement method - Google Patents
Partial discharge measurement methodInfo
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- JPH068846B2 JPH068846B2 JP1309743A JP30974389A JPH068846B2 JP H068846 B2 JPH068846 B2 JP H068846B2 JP 1309743 A JP1309743 A JP 1309743A JP 30974389 A JP30974389 A JP 30974389A JP H068846 B2 JPH068846 B2 JP H068846B2
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- partial discharge
- noise
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- mhz
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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。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Ｃｘ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
ら高周波成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 conventional partial discharge measurement method is shown in FIG. 4 (A).
As shown in FIG. 4, a detection impedance 4 is inserted between the coupling capacitor 3 and the ground in the vicinity of the terminal connection portion of the power cable 1 (illustrated as a capacitance C x for convenience), or as shown in FIG. As shown, 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 high frequency components are extracted 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
成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。In the configuration of FIG. 4 (A) or (B), the high voltage AC terminal 2 is applied with an AC high voltage, and the power transmission line constituted by the power cable 1 is in a live line state. When a partial discharge occurs in the insulator, a potential difference is generated across the detection impedance 4. The partial discharge in the insulator is measured based on this potential difference.
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。Methods of measuring partial discharge using such a circuit are roughly classified into the following three types.
(1)低周波測定法（測定周波数１５ｋＨｚないし１５０
ｋＨｚ） (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Ｍ
Ｈｚ） 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 15 kHz to 150
(2) Wideband measurement method (measurement frequency: several kHz to several MH)
z) (3) Tuning method (measurement frequency 100 kHz or several M
Hz) In the case of the tuning type measurement method, generally, the tuning frequency is selected from several fixed frequencies with a switch and used.
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ほかな
く、部分放電測定の高い感度を得ることが困難であっ
た。However, in the case of the above-mentioned tuning type measurement method, in the method of fixing the tuning frequency, even if large noise is observed at the frequency used for measurement, there is no choice but to measure at that frequency and to obtain high sensitivity of partial discharge measurement. Was difficult.
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。In particular, the partial discharge pulse generated at a place far from the end connection part of a long cable, such as an intermediate connection part, is attenuated by the inductance of the cable until it reaches the detection part, and the influence of external noise is also large. Become, S / N
The 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成分、サイリスタ等の機器から生
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
するもの等から成ると見られる。The detected noise is mainly derived from harmonic components contained in the transmission current of the commercial AC power cable, pulses generated from equipment such as thyristors, electromagnetic waves in the air such as broadcasting,
It is thought to be composed of the ground potential floating due to the noise 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 becomes low at that frequency for the reason described later. That is, the change of the S / N ratio with frequency in the partial discharge measurement is extremely complicated and changes depending on the structure of the power transmission and distribution system, the place where the partial discharge occurs, the measurement place, the measurement time, etc., so it is extremely impossible to predict. It was difficult to obtain a high S / N ratio.
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 capable of detecting a partial discharge in a power cable, particularly a long cable with high sensitivity, that is, a high S / N ratio.
上記目的を達成するため本発明では、電力ケーブル線路
にインピーダンスを接続し、 検出インピーダンスを介し、電力ケーブル線路からのノ
イズ性出力信号を検出し、 電力ケーブル線路に較正パルスを注入し、検出インピー
ダンスを介して較正パルス及びノイズを含んだ出力信号
を検出し、 ノイズ性出力信号と、較正パルス及びノイズを含んだ出
力信号のそれぞれの周波数スペクトルを求め、 それぞれの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
スを測定することを特徴とする部分放電測定方法を提供
する。To achieve the above object, the present invention connects an impedance to a power cable line, detects a noisy output signal from the power cable line through a detection impedance, injects a calibration pulse into the power cable line, and detects the detection impedance. The output signal containing the calibration pulse and the noise is detected via the above, and the frequency spectrums of the noisy output signal and the output signal containing the calibration pulse and the noise are obtained, and the frequency dependence of the S / N ratio is determined from the respective frequency spectra. The present invention provides a method for measuring partial discharge, characterized by measuring the partial discharge pulse at a frequency having a high S / N ratio.
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。The frequency spectrum of the calibration pulse and noise can be obtained using a frequency sweep type spectrum analyzer. The frequency spectrum measurement of the noisy signal may be before or after the frequency spectrum measurement of the calibration pulse.
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、ケーブルシースあるいは絶縁接続箱等
において離隔されたシース間に注入してもよい。較正パ
ルスをシースへ注入する場合は、活線状態でも可能であ
り、安全性の点でも有利である。The calibration pulse may be injected directly between the conductor of the power cable and the sheath, or it may be injected between the sheaths separated by a cable sheath or an insulation junction box. When the calibration pulse is injected into the sheath, it can be performed in a live state, which is advantageous in terms of safety.
前述のようにＳ／Ｎ比の周波数依存正は場所や時期によ
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、サイリスタから生ずるパルス成分等の介入
を避けるため、測定周波数は１０ｋＨｚ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
１００ＭＨｚ程度である。As described above, since the frequency dependence of the S / N ratio is not constant depending on the place and the time, it is preferable to continuously change the measurement frequency. The measurement frequency is preferably selected from 10 kHz or higher in order to avoid the interference of harmonics contained in the transmission current of the commercial AC power cable and the pulse component generated from the thyristor. The upper limit of the frequency range is not particularly limited, but is usually about 100 MHz.
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。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。In the partial discharge measuring method of the present invention, when the partial discharge occurs in the insulating layer, a pulse current flows through the inner conductor in the forward path, the outer semiconducting layer and the outer metal sheath, and possibly the wire shield in the return path. This pulse current causes a potential difference across the detection impedance. In the method of the present invention, the measurement frequency at which the S / N ratio is as high as possible in the calibration of the detection sensitivity by the calibration pulse is selected, and the partial discharge pulse is measured at that frequency. Unlike the measurement method that measures at a fixed frequency or the measurement method that does not consider the frequency dependence of the signal level, the highest S /
Since the measurement frequency at which the N ratio is obtained can be selected and used, 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。The frequency dependence of noise confirmed by the present inventor will be described below before describing the embodiments of the present invention.
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。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。第５図
（Ｂ）は３．０ＭＨＺ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３．８ＭＨｚ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３．９５ＭＨ
ｚでノイズレベルが高く、これに比し３．８８ＭＨｚお
よび４．０ないし４．１５ＭＨｚにノイズレベルがかな
り低い所がある。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。A 66 kV CV cable with a length of 10 m is used as a test cable, and a frequency sweeping type signal strength measuring instrument is connected as the measuring device 5 in the circuit shown in FIG. The frequency spectrum of the pulse detected in the above condition was as shown in FIGS. 5 (A) to 5 (C). FIG. 5 (A) is a frequency spectrum of noise in a frequency range up to 10 MHz. It shows that the noise level is particularly high near 4 MHz. FIG. 5 (B) is an enlarged view of the range of 3.0 MHz to 5.0 MHz, and FIG. 5 (C) is an enlarged view of only the range of 3.8 MHz to 4.2 MHz. It can be seen that the noise level has a large frequency dependency. As is clear from FIG. 5 (C), near 4 MHz,
Especially around 3.82MHz and 3.92 to 3.95MH
The noise level is high at z, and there are considerably lower noise levels at 3.88 MHz and 4.0 to 4.15 MHz. The noise level at 3.88 MHz is about 35 dB lower than 3.82 MHz. As described above, noise often shows a bright line spectrum, and there is often a region having a considerably low noise level in the vicinity thereof.
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。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。Not only the frequency distribution of noise but also the signal detection sensitivity of the partial discharge pulse has a complicated frequency distribution. The following factors are considered for both noise and partial discharge pulse.
(1)電力ケーブルの回路構成は複雑で、多くのＬ、Ｃ成
分等があり、これらによる種々の周波数での共振、***
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 the power cable is complicated, and there are many L and C components. Due to these, resonance and antiresonance occur at various frequencies, and the amplitude thereof changes intricately 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 mismatched state, a standing wave occurs, and when the detection point hits the valley of the standing wave, low detection sensitivity is given, and when it hits the belly. Provides high detection sensitivity.
〔実施例１〕 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。Example 1 A first example 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成る。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は静電容量Ｃｘとし
て表示した。供試ケーブル１は長さ１０ｍの６６ｋＶ用
ＣＶケーブルで、高電圧課電端子２から高電圧を課電さ
れる。A circuit used in the partial discharge detection method according to the present invention is shown in FIG. In the circuit of FIG. 1, a coupling capacitor 3 and a detection impedance 4 are connected between a high-voltage conductor connected to the high-voltage charging terminal 2 and ground, and a measuring device 5 is connected in parallel to the detection impedance 4. The measuring device 5 comprises a spectrum analyzer and a pulse counting device. A pulse generator 6 was connected between the high-voltage conductor and the sheath of the test cable 1. In FIG. 1, the test cable 1 is shown as a capacitance C x . The test cable 1 is a 66-kV CV cable having a length of 10 m, and a high voltage is applied from the high-voltage charging terminal 2.
ケーブル１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 obtained by this circuit under the condition that the cable 1 was not charged and the pulse generator 6 was not operated, that is, only the noise was generated. 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（ピコクーロン）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, in the circuit shown in FIG. 1, the pulse generator 6 connected between the conductor side of the cable under test 1 and the sheath is activated, and a calibration pulse of 100 pC (pico coulomb) is injected from the pulse generator 6. In that state, the frequency dependency of the detection pulse was obtained 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５．５ＭＨｚ、６．２ＭＨｚ、９．２ＭＨｚであ
り、これらの周波数ではＳ／Ｎ比も高い。Comparing FIG. 2 (A) and FIG. 2 (B), about 3 MH
If it is less than z, the contribution of the injection pulse is small even when the calibration pulse is injected, and most of it is noise, but at 3.5 MHz or more, the signal level maintains a level near -50 dB, whereas noise is -60 dB or less except near 4 MHz. The noise remarkably decreases between 4.5 MHz and 5.5 MHz, and becomes −70 dB or less at higher frequencies. After all, S / at 4.8MHz to 10MHz
It can be seen that the N ratio becomes high. Particularly, the noise level is low at 5.5 MHz, 6.2 MHz and 9.2 MHz, 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１／５
０、すなわち２ｐＣに相当する）。４．８ＭＨｚから１
０ＭＨｚ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。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 (detection limit is therefore 1/5 of 100 pC)
0, or 2 pC). 4.8MHz to 1
Even in the 0MHz range, the noise level is about -70dB and the signal level is -48dB when measured at 8.4MHz.
Therefore, only an S / N ratio of about 22 dB can be obtained.
This indicates that even a small difference in the measured frequency causes a large difference in the S / N ratio.
第２図（Ａ）に見られるように、周波数３．０ないし
３．２ＭＨｚではノイズレベルが比較的低く（約−６６
ｄＢ）、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。As shown in FIG. 2 (A), the noise level is relatively low (about −66 at frequencies of 3.0 to 3.2 MHz).
dB), which is close to that of 4.5 MHz or more, but at this frequency the signal level drops to about -58 dB, and only an S / N ratio of about 8 dB can be obtained. That is 4.8M
The S / N ratio is 20 dB or more lower than that 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１０ｋＨｚないし１５０ｋＨｚおよび１０ｋＨｚ
ないし１０００ｋＨｚ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７０ｐ
Ｃであった。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。Here, we tried the conventional low-frequency measurement. Amplification frequency band is 10kHz to 150kHz and 10kHz using low frequency detection impedance and band pass filter.
Or continuously changing in the range of 1000 kHz to S
When the / N ratio was measured, the detection limit was at most about 70p.
It was C. From this, it was confirmed that the low frequency method was not very sensitive.
以上の測定結果に基づき、５．５ＭＨｚ、６．２ＭＨ
ｚ、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, 6.2MH
5.5 MHz was selected from z and 9.2 MHz, and the pulse discharge device of the measuring device 5 was used to measure the partial discharge of the power cable in a live state.
従来の同調式部分放電測定器（(株)日本計測器製造所
製）を用いて、部分放電測定を行った。Partial discharge measurement was performed using a conventional tuning type partial discharge measuring instrument (manufactured by Nippon Keiki Seisakusho Co., Ltd.).
この測定器の使用周波数は４００ｋＨｚである。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倍である（感度で１／１
５）。The operating frequency of this measuring device is 400 kHz. S / N
The ratio was 10 dB and the detection limit was 30 pC. this is,
This is 15 times the detection limit (2 pC) when 5.5 MHz is selected and measured using the method of the present invention (1/1 in sensitivity).
5).
〔実施例２〕 実施例１においてはパルス発生器６を供試ケーブル１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１ａ，１ｂを接続する絶縁接続
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１ａ側の
シース７ａとケーブル１ｂ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
の無課電状態で行った。[Example 2] In Example 1, the pulse generator 6 was connected between the inner conductor and the sheath of the sample cable 1, but in this Example, as shown in Fig. 3, insulation for connecting the cables 1a and 1b was used. Metal foil electrode 8a attached to the outside of each insulating sheath of the connecting portion 7
The pulse generator 6 was connected between the and 8b. Then, the detection impedance 4 and the measuring device 5 were connected between the sheath 7a on the cable 1a side and the sheath 7b on the cable 1b side. The connection between the pulse generator 6 and the measuring device 5 was performed with the cable being unpowered.
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。Similar to the first embodiment, 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 spectrum of the noise and the frequency spectrum of the calibration pulse are compared to determine the S / N ratio. Found the highest frequency of.
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５．５ＭＨｚ
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。Next, the operation of the pulse generator 6 is stopped, and the partial discharge of the cable in a live state is performed at the frequency of 5.5 MHz selected above.
It was measured at. As a result, the partial discharge could be measured at an S / N ratio almost equal to that in Example 1. The metal foil electrodes 8a and 8b may be attached and the pulse generator 6 may be connected while the cable is live.
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。特に、長尺ケー
ブルの場合に有用である。According to the partial discharge measuring method of the present invention, the partial discharge in the power cable can be detected with high sensitivity. It 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 by the conventional method of measuring at a fixed frequency or simply avoiding a frequency with a large amount of 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）はノイ
ズの周波数スペクトルを示すグラフである。 符号の説明 １，１ａ，１ｂ………電力ケーブル ２………高電圧課電端子 ３………結合コンデンサ ４………検出インピーダンス ５………測定装置 ６………パルス発生器 ７………絶縁接続部 ７ａ，７ｂ………絶縁接続部シース ８ａ，８ｂ………金属箔電極FIG. 1 is an explanatory view showing a circuit used in an embodiment of the partial discharge detection method of the present invention, FIG. 2 (A) is a graph showing a frequency spectrum of only measured noise, and FIG. 2 (B) is FIG. 3 is a graph showing a frequency spectrum of a signal measured when a calibration pulse is injected, FIG. 3 is an explanatory view showing another embodiment of the present invention, and FIGS. 4 (A) and 4 (B) are conventional partial discharge measurement methods. And FIGS. 5A to 5C are graphs showing the frequency spectrum of noise. Explanation of symbols 1, 1a, 1b ……… Power cable 2 ……… High-voltage charging terminal 3 ……… Coupling capacitor 4 ……… Detection impedance 5 ……… Measuring device 6 ……… Pulse generator 7 …… … Insulated connection parts 7a, 7b ……… Insulated connection part sheaths 8a, 8b ……… Metal foil electrodes
Claims (3)
接続し、 前記検出インピーダンスを介し、前記電力ケーブル線路
からのノイズ性出力信号を検出し、 前記電力ケーブル線路に較正パルスを注入し、前記検出
インピーダンスを介して較正パルス及びノイズを含んだ
出力信号を検出し、 前記ノイズ性出力信号と、前記較正パルス及びノイズを
含んだ出力信号のそれぞれの周波数スペクトルを求め、 前記それぞれの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
パルスを測定することを特徴とする部分放電測定方法。1. A detection impedance is connected to a power cable line, a noise output signal from the power cable line is detected through the detection impedance, a calibration pulse is injected into the power cable line, and the detection impedance is set. An output signal containing a calibration pulse and noise is detected via the output signal, and a frequency spectrum of each of the output signal containing the noise pulse output signal and the calibration pulse and noise is obtained, and an S / N ratio is obtained from each frequency spectrum. And a partial discharge pulse is measured at a frequency having a high S / N ratio.
ースとの間に注入する請求項１記載の部分放電測定方
法。2. The method for measuring partial discharge according to claim 1, wherein the calibration pulse is injected between the conductor and the sheath of the power cable.
離されたシース間に注入する請求項１記載の部分放電測
定方法。3. The method for measuring partial discharge according to claim 1, wherein the calibration pulse is injected between sheaths separated from each other such as an insulating connection.
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 JPH03170076A (en) | 1991-07-23 |
| JPH068846B2 true 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 |
|---|---|
| JPH03170076A (en) | 1991-07-23 |
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