JPH079447B2 - Insulation resistance measuring method and device - Google Patents
Insulation resistance measuring method and deviceInfo
- Publication number
- JPH079447B2 JPH079447B2 JP18273085A JP18273085A JPH079447B2 JP H079447 B2 JPH079447 B2 JP H079447B2 JP 18273085 A JP18273085 A JP 18273085A JP 18273085 A JP18273085 A JP 18273085A JP H079447 B2 JPH079447 B2 JP H079447B2
- Authority
- JP
- Japan
- Prior art keywords
- frequency
- component
- signal
- low
- insulation resistance
- 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.)
- Expired - Lifetime
Links
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は活線状態にて電路等の絶縁抵抗を測定する方法
及びその方法を用いた絶縁抵抗測定装置の構成に関す
る。Description: TECHNICAL FIELD The present invention relates to a method for measuring insulation resistance of an electric circuit or the like in a live state, and a configuration of an insulation resistance measuring apparatus using the method.
（従来技術） 従来より漏電等の早期発見のために電路の絶縁抵抗を常
時監視することが行われているが、この種の測定方法と
しては第２図に示すものが一般的であった。(Prior Art) Conventionally, the insulation resistance of an electric circuit has been constantly monitored for early detection of a leakage or the like, but as a measurement method of this type, a method shown in FIG. 2 has been generally used.
受電変圧器Ｔの二次側電路L1、L2のうち一方の電路L2に
第２種接地線LEが設けられ、前記電路L1、L2が負荷Ｚで
終端された電路の絶縁抵抗監視には同図に示すごとく、
接地線LEに挿入した発振器OSC1より商用周波数と異なる
低周波信号f1を電路L1、L2に印加すると共に、接地線LE
に零相変流器ZCT1を結合せしめ、電路L1、L2と大地との
間に存在する絶縁抵抗Ｒと対地浮遊容量Ｃとを介して接
地線LEに還流する前記低周波信号f1漏洩電流をバンドパ
スフィルタBPF1によって抽出し、該バンドパスフィルタ
BPF1出力と前記発振器OSC1出力とを掛け算器MULT1に入
力し、同期検波することによって電路の絶縁抵抗を測定
するものであった。Type 2 ground line L E is provided in the path L 2 one of the power receiving transformer secondary path L 1 of T, L 2, insulation of electric path the path L 1, L 2 is terminated by a load Z For resistance monitoring, as shown in the figure,
And it applies from the oscillator OSC 1 inserted into the ground line L E and commercial frequencies different low frequency signals f 1 to path L 1, L 2, a ground line L E
The zero-phase current transformer ZCT 1 is coupled to the low-frequency signal f that flows back to the ground line L E via the insulation resistance R and the ground stray capacitance C existing between the electric lines L 1 and L 2 and the ground. 1 Leakage current is extracted by the bandpass filter BPF 1
The BPF 1 output and the oscillator OSC 1 output are input to a multiplier MULT 1 and synchronous detection is performed to measure the insulation resistance of the electric path.
従来の絶縁抵抗値算出方法を以下簡略に説明する。A conventional insulation resistance value calculation method will be briefly described below.
第２図の測定を等価回路にて表わせば第３図に示すごと
く低周波発振器OSC1に並列に絶縁抵抗Ｒと浮遊容量Ｃと
が接続されたものとなり、これらを介して接地線に帰還
いる電流をI1すれば、 I1＝（V/R）＋ｊω1CV ……（１） 但し、Ｖは発振器OSC1の印加信号であって、低周波信号
の振幅値の実効値またはピーク電圧値、ω１は印加する
低周波信号f1の角速度でω１＝２πf1である。If the measurement of FIG. 2 is represented by an equivalent circuit, as shown in FIG. 3, an insulation resistance R and a stray capacitance C are connected in parallel to the low frequency oscillator OSC 1 , and the feedback is made to the ground line via these. If the current is I 1 , I 1 = (V / R) + jω 1 CV (1) However, V is the applied signal of the oscillator OSC 1 , and the effective value of the amplitude value of the low frequency signal or the peak voltage value , Ω 1 is the angular velocity of the low-frequency signal f 1 to be applied, and ω 1 = 2πf 1 .
いま（１）式で表わされる電流I1を発振器OSC1の出力を
用いて同期検波等の手段によって同相成分（有効分）、
即ち、同式右辺第１項を抽出すれば、絶縁抵抗Ｒに逆比
例した値となり、これから絶縁抵抗を導出することがで
きる。Now, the current I 1 represented by the equation (1) is in-phase component (effective component) by means such as synchronous detection using the output of the oscillator OSC 1 .
That is, if the first term on the right side of the equation is extracted, the value becomes inversely proportional to the insulation resistance R, and the insulation resistance can be derived from this.
しかしながら、この方法によれば電路の対地浮遊容量が
大きくなると（１）式右辺第２項によって表わされる漏
洩電流の無効成分が大きくなり、上述した同期検波回路
等のダイナミックレンジの制約から有効成分の正確な抽
出が困難となる欠陥があった。However, according to this method, when the stray capacitance to the ground of the electric path becomes large, the reactive component of the leakage current represented by the second term on the right side of the equation (1) becomes large, and the effective component of the effective component is reduced due to the restriction of the dynamic range of the synchronous detection circuit described above. There was a defect that made accurate extraction difficult.
この無効成分を小さくする手段としては、印加する低周
波信号f1の周波数を低くすることも考えられるが、この
場合には低周波信号の印加にあたって使用するトランス
或いは漏洩電流の導出にあたって使用する零相変流器の
リアクタンスを大きくすべく形状が大型とならざるを得
ず、不経済であった。As a means for reducing this ineffective component, it is conceivable to lower the frequency of the low frequency signal f 1 to be applied, but in this case, the transformer used for applying the low frequency signal or the zero used for deriving the leakage current is used. The shape was inevitably large in order to increase the reactance of the phase current transformer, which was uneconomical.
一般には前記低周波信号f1としては10〜30Hz程度が使用
されるため、対地浮遊容量の増大によって絶縁抵抗の測
定は極めて困難であった。Generally, about 10 to 30 Hz is used as the low frequency signal f 1 , so that it is extremely difficult to measure the insulation resistance due to an increase in the floating capacitance to ground.
（発明の目的） 本発明はこのような従来の電路の絶縁抵抗測定方法の欠
陥を除去すべくなされたものであって、浮遊容量の増大
に関係なく、常に正確な抵抗測定を可能とした方法を提
供することを目的とする。(Object of the Invention) The present invention has been made to eliminate such defects of the conventional method for measuring insulation resistance of an electric circuit, and a method that always enables accurate resistance measurement regardless of increase in stray capacitance. The purpose is to provide.
（発明の概要） この目的のため本発明では電路に印加する低周波信号を
２波とし、この２つの低周波信号の漏洩成分のうち、一
方を他方の周波数と同一になる如く周波数変換すると共
に、該周波数変換した信号と前記他方の信号とを減算し
無効成分を相殺せしめることによって絶縁抵抗に逆比例
した有効成分のみを導出し、もって無効成分に無関係に
電路の絶縁抵抗を検出するように構成する。(Summary of the Invention) For this purpose, the present invention uses two low-frequency signals applied to the electric path, and performs frequency conversion so that one of the leakage components of these two low-frequency signals becomes equal to the other frequency. , The frequency-converted signal is subtracted from the other signal to cancel the ineffective component, so that only the effective component inversely proportional to the insulation resistance is derived, and thus the insulation resistance of the electric path is detected regardless of the ineffective component. Constitute.
（実施例） 以下、本発明を図示した実施例に基づいて詳細に説明す
る。(Example) Hereinafter, the present invention will be described in detail based on illustrated examples.
電路に印加する低周波信号を更にもう一つ追加し、この
周波数をf2とすると、これによる漏洩電流I2は I2（V/R）＋ｊω2CV ……（２） と表わされる。If another low frequency signal to be applied to the circuit is added and this frequency is f 2 , the leakage current I 2 due to this is expressed as I 2 (V / R) + jω 2 CV (2).
但し、ω２＝２πf2とし、Ｖは周波数f2の低周波信号の
振幅値の実効値またはピーク電圧値であって、前記第一
の周波数f1と低周波信号の振幅値と同一値とする。However, ω 2 = 2πf 2 and V is the effective value or the peak voltage value of the amplitude value of the low frequency signal of the frequency f 2 , and is the same value as the amplitude value of the first frequency f 1 and the low frequency signal. To do.
そこで前記（１）式の両辺にω2/ω１を乗じた上で
（２）式を引き算し、整理すれば （V/R）｛（ω2/ω１）−１｝＝（ω2/ω１）I1−I2 …
…（３） が求まる。Therefore, if both sides of the equation (1) are multiplied by ω 2 / ω 1 and the equation (2) is subtracted and rearranged, (V / R) {(ω 2 / ω 1 ) −1} = (ω 2 / ω 1 ) I 1 −I 2 …
… (3) is obtained.
（３）式から明らかなように引き算した結果には無効成
分が含まれないから電路の無効成分の増大に関係なく絶
縁抵抗を求めることができる。As is clear from the equation (3), the result of subtraction does not include the ineffective component, so that the insulation resistance can be obtained regardless of the increase of the ineffective component of the electric path.
第１図は本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing an embodiment of the present invention.
同図において、Ｔ、L1、L2、ZCT及びLEは第２図と同様
に受電変圧器、二次側電路、零相変流器ZCT及び第２種
接地線であって、該接地線LEに結合した発振器OSC2は、
夫々周波数が異なるf1、f2の２つの低周波信号を同時に
電路に出力すると共に周波数f1＋f2なる信号を後述する
変調器MODに出力するものである。In the same figure, T, L 1 , L 2 , ZCT and L E are the receiving transformer, the secondary side electric circuit, the zero-phase current transformer ZCT and the second type grounding wire, as in FIG. The oscillator OSC 2 coupled to line L E is
Two low-frequency signals of f 1 and f 2 each having different frequencies are simultaneously output to the electric circuit, and a signal of frequency f 1 + f 2 is output to the modulator MOD described later.
また零相変流器ZCT出力は２つに分岐し、そのうち一方
の出力は周波数f1のみを抽出するバンドパスフィルタBP
F2と増幅器AMPを介して減算器SUBTの一方の入力端に入
力し、また零相変流器ZCT出力のうち他方の分岐出力は
周波数f2のみを抽出するバンドパスフィルタBPF3、変調
器MOD、ローパスフィルタLPF及び移相器PSを介して前記
減算器SUBTのもう一方の入力端に入力し、前記変調器MO
Dの変調信号入力端には前記発振器のOSC2が出力する周
波数f1＋f2なる信号を入力する。The output of the zero-phase current transformer ZCT is branched into two, one of which is a bandpass filter BP that extracts only the frequency f 1.
Bandpass filter BPF 3 that inputs to one input terminal of subtractor SUBT via F 2 and amplifier AMP, and the other branch output of zero-phase current transformer ZCT extracts only frequency f 2 Input to the other input terminal of the subtractor SUBT via the MOD, low pass filter LPF and phase shifter PS, and the modulator MO
A signal of frequency f 1 + f 2 output by the OSC 2 of the oscillator is input to the D modulation signal input terminal.
発振器OSC2が変調器MODに供給している周波数f1＋f2信
号発生方法は周波数f1なる信号と周波数f2なる信号の積
をとることにより周波数f1±f2の信号を得、フィルタ等
を用いて周波数f1＋f2の成分を抽出すればよい。Frequency f 1 + f 2 signal generating method oscillator OSC 2 is supplied to the modulator MOD to obtain a signal of a frequency f 1 ± f 2 by taking the product of the frequency f 1 becomes the signal and the frequency f 2 becomes signal, filter The component of frequency f 1 + f 2 may be extracted by using, for example.
以下、このように構成した絶縁抵抗測定装置の動作を数
式を用いて説明する。Hereinafter, the operation of the insulation resistance measuring device configured as described above will be described using mathematical expressions.
発振器OSC2から電路に印加する２つの信号f1、f2の電圧
を共に同一のＶ（ボルト）とすれば、バンドパスフィル
タBPF2出力（信号f1出力）x1は x1＝（V/R）sinω1t＋ω1CVcosω1t ……（４） と表わされ、またバンドパスフィルタBPF3の出力（周波
数f2出力）x2は x2＝（V/R）sinω2t＋ω2CVcosω2t ……（５） と表わされる。If the voltages of the two signals f 1 and f 2 applied from the oscillator OSC 2 to the circuit are the same V (volts), the bandpass filter BPF 2 output (signal f 1 output) x 1 is x 1 = (V / R) sinω 1 t + ω 1 CVcosω 1 t (4) and the output (frequency f 2 output) x 2 of the bandpass filter BPF 3 is x 2 = (V / R) sinω 2 t + ω 2 CVcosω It is expressed as 2 t ...... (5).
前記バンドパスフィルタBPF3出力と発振器OSC2が出力す
る周波数f1＋f2なる信号とを変調器MODに入力すると、
変調器MODの出力には周波数f2±（f1＋f2）の２つの混
合成分が含まれ、次段のローパスフィルタLPFにて両者
の差分ｙ、即ち周波数f1成分のみを抽出すれば、周波数
f2周波数f1に周波数シフトしたものとなる。When the bandpass filter BPF 3 output and the signal of frequency f 1 + f 2 output by the oscillator OSC 2 are input to the modulator MOD,
The output of the modulator MOD contains two mixed components of frequency f 2 ± (f 1 + f 2 ), and if only the difference y between them, that is, the frequency f 1 component is extracted by the low pass filter LPF at the next stage, frequency
The frequency is shifted to f 2 frequency f 1 .
即ち、（５）式にて示されるバンドパスフィルタBPF3の
出力x2は、角周波数ω２をもった周波数f2の漏洩成分で
あるが、これに変調器MODにおいて（f1＋f2）なる信号
を混合すると、変調器MOD出力は両者の和である周波数f
1＋2f2成分を含む信号と両者の差である周波数f1成分を
含む信号となり、このうち両者の差である周波数f1成分
を含む信号は（５）式の角周波数ω２をω２−（ω１＋
ω２）に置換したものとなる。That is, the output x 2 of the bandpass filter BPF 3 represented by the equation (5) is a leakage component of the frequency f 2 having the angular frequency ω 2 , which is (f 1 + f 2 ) in the modulator MOD. , The modulator MOD output is the sum of the two, and the frequency f
1 + 2f signal becomes including frequency f 1 component which is the difference signal and both comprising two components, a signal including frequency f 1 component which is the difference between these two is (5) of the angular frequency omega 2 and omega 2 - (Ω 1 +
It is replaced with ω 2 ).
したがって、差分ｙは次式で表わされる。Therefore, the difference y is expressed by the following equation.
ｙ＝（V/R）sin｛ω２−（ω１＋ω２）｝ｔ ＋ω2CVcos｛ω２−（ω１＋ω２）｝ｔ＝ −（V/R）sinω１＋ω2CVcosω1t ……（６） そこで、前記バンドパスフィルタBPF2出力を次段の増幅
器AMPによってω2/ω１倍したものとローパスフィルタL
PF出力とを減算器SUBTに入力し、引き算すれば (ω１+ω２)x１-y=(V/R){(ω２/ω１)+1}sinω１t ……
（７） となって、これは低周波信号の漏洩成分の有効分に比例
した信号であるから、これを整流するか或いは同期検波
することにより電路の絶縁抵抗を求めることができる。y = (V / R) sin {ω 2 - (ω 1 + ω 2)} t + ω 2 CVcos {ω 2 - (ω 1 + ω 2)} t = - (V / R) sinω 1 + ω 2 CVcosω 1 t ... (6) Therefore, the output of the bandpass filter BPF 2 is multiplied by ω 2 / ω 1 by the amplifier AMP at the next stage and the lowpass filter L.
Input the PF output to the subtractor SUBT and subtract it (ω 1 + ω 2 ) x 1 -y = (V / R) {(ω 2 / ω 1 ) +1} sinω 1 t ......
(7) Since this is a signal proportional to the effective component of the leakage component of the low frequency signal, the insulation resistance of the electric path can be obtained by rectifying or synchronously detecting the signal.
尚、移相器PSは減算器SUBTにおいて引き算する２つの信
号の位相を補正するためのものである。The phase shifter PS is for correcting the phases of the two signals subtracted by the subtractor SUBT.
このように構成すれば、以上の説明から明らかな如く漏
洩電流の無効成分に無関係に絶縁抵抗を求めることがで
きる。With this configuration, the insulation resistance can be obtained irrespective of the reactive component of the leakage current as is clear from the above description.
本発明の実施にあたっては上述した実施例に限定する必
要はなく、他にも種々のものが考えられる。例えば、電
路に印加する周波数f1、f2の信号電圧はV1とV2のごとく
異なってもよく、この場合は増幅器AMPの利得を（V2/
V1）・（ω2/ω１）とすれば良いことは容易に理解でき
よう。In carrying out the present invention, it is not necessary to limit to the above-mentioned embodiments, and various other ones can be considered. For example, the signal voltages of frequencies f 1 and f 2 applied to the electric path may be different as V 1 and V 2 , and in this case, the gain of the amplifier AMP is (V 2 /
It can be easily understood that it is better to set V 1 ) · (ω 2 / ω 1 ).
（発明の効果） 本発明は以上説明したように構成するものであるから、
無効分の影響を受けずに正確に電路の絶縁抵抗を求める
うえで著効を奏する。(Effects of the Invention) Since the present invention is configured as described above,
It is extremely effective in accurately determining the insulation resistance of the electric circuit without being affected by the reactive component.
第１図は本発明の絶縁抵抗測定方法の一実施例を示すブ
ロック図、 第２図は従来の絶縁抵抗測定回路を示すブロック図、 第３図は第２図の等価回路図である。 Ｔ……受電変圧器、 L1、L2……電路、 Ｒ……絶縁抵抗、 Ｃ……対地静電容量、 Ｚ……電路の負荷、 ZCT……零相変流器、 OSC1、OSC2……発振器、 BPF1、BPF2、BPF3……バンドパスフィルタ、 MULT1……同期検波器、 LPF……ローパスフィルタ、 PS……移相器、 SUBT……減算器FIG. 1 is a block diagram showing an embodiment of the insulation resistance measuring method of the present invention, FIG. 2 is a block diagram showing a conventional insulation resistance measuring circuit, and FIG. 3 is an equivalent circuit diagram of FIG. T …… Reception transformer, L 1 , L 2 …… Circuit line, R …… Insulation resistance, C …… Capacitance to ground, Z …… Circuit load, ZCT …… Zero-phase current transformer, OSC 1 , OSC 2 …… Oscillator, BPF 1 , BPF 2 , BPF 3 …… Band pass filter, MULT 1 …… Synchronous detector, LPF …… Low pass filter, PS …… Phase shifter, SUBT …… Subtractor
Claims (2)
周波数と異なる周波数f1及びf2の二つの低周波信号の対
地漏洩電流を前記接地線に結合した変流器及びこれに接
続したバンドパスフィルタによって分離抽出すると共
に、該二つの低周波信号の漏洩電流成分のうち周波数f2
成分の信号を、電路に印加した周波数f1及びf2の低周波
信号を用いて周波数f1の信号となるように周波数変換
し、該周波数変換して得た周波数f1の信号成分と前記バ
ンドパスフィルタによって分離抽出した周波数f1の漏洩
電流成分とを減算して、漏洩電流成分の有効成分のみを
導出したことを特徴とする絶縁抵抗測定方法。1. A current transformer coupled to a grounding wire and a current transformer connected to the grounding wire, which is applied to an electric circuit via a grounding wire and which leaks two ground low-frequency signals having low frequencies f 1 and f 2 different from the commercial power frequency. Of the leakage current components of the two low-frequency signals and the frequency f 2
The signal of the component is frequency-converted to be a signal of frequency f 1 using low-frequency signals of frequencies f 1 and f 2 applied to an electric circuit, and the signal component of frequency f 1 obtained by the frequency conversion and An insulation resistance measuring method characterized in that only the effective component of the leakage current component is derived by subtracting the leakage current component of frequency f 1 separated and extracted by a bandpass filter.
周波数f1、f2の二つの低周波信号を印加すると共に、該
二つの低周波信号の対地漏洩電流を前記接地線から導出
する手段と、 前記導出された二つの低周波信号のうち周波数f2成分の
漏洩電流と電路に印加した二つの低周波信号の周波数和
（f1＋f2）の信号とを混合する手段と、 前記混合手段出力からf1成分のみを抽出する手段と、 該抽出手段の出力と前記導出手段出力のうち周波数f1成
分の信号とを入力して両出力を減算する手段とを備えた
ことを特徴とする絶縁抵抗測定装置。 2. A low-frequency signal having frequencies f 1 and f 2 different from the commercial frequency is applied to the electric line via a ground wire, and a ground leakage current of the two low-frequency signals is derived from the ground wire. Means for mixing the leakage current of the frequency f 2 component of the derived two low-frequency signals and a signal of the frequency sum (f 1 + f 2 ) of the two low-frequency signals applied to the electric path, It is characterized by comprising means for extracting only the f 1 component from the output of the mixing means, and means for receiving the output of the extracting means and the signal of the frequency f 1 component of the output of the deriving means and subtracting both outputs. Insulation resistance measuring device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18273085A JPH079447B2 (en) | 1985-08-20 | 1985-08-20 | Insulation resistance measuring method and device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18273085A JPH079447B2 (en) | 1985-08-20 | 1985-08-20 | Insulation resistance measuring method and device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6243572A JPS6243572A (en) | 1987-02-25 |
| JPH079447B2 true JPH079447B2 (en) | 1995-02-01 |
Family
ID=16123437
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18273085A Expired - Lifetime JPH079447B2 (en) | 1985-08-20 | 1985-08-20 | Insulation resistance measuring method and device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH079447B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4857855A (en) * | 1988-11-03 | 1989-08-15 | Toyo Communication Equipment Co., Ltd. | Method for compensating for phase of insulation resistance measuring circuit |
| US4851761A (en) * | 1988-11-03 | 1989-07-25 | Toyo Communication Equipment Co., Ltd. | Method for measuring insulation resistance of electric line |
| US4857830A (en) * | 1988-11-03 | 1989-08-15 | Toyo Communication Equipment Co., Ltd. | Method for measuring insulation resistance of electric line |
| PL233390B1 (en) * | 2017-11-14 | 2019-10-31 | Politechnika Gdanska | Method and system for assessing condition of electric insulation in electrical equipment |
-
1985
- 1985-08-20 JP JP18273085A patent/JPH079447B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6243572A (en) | 1987-02-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4851761A (en) | Method for measuring insulation resistance of electric line | |
| JPH079447B2 (en) | Insulation resistance measuring method and device | |
| JP2617324B2 (en) | Insulation resistance measurement method | |
| JPH0552466B2 (en) | ||
| JPH0354311B2 (en) | ||
| JP2750705B2 (en) | Insulation resistance measurement method | |
| JPS61155869A (en) | Measuring method of phase-compensated insulation resistance | |
| JP2764584B2 (en) | Measurement method of insulation resistance of branch circuit | |
| JP2612703B2 (en) | Insulation resistance measurement method with canceling ground resistance | |
| JP2896572B2 (en) | Simple insulation resistance measurement method | |
| JPS58127172A (en) | Insulation resistance measuring apparatus for electric line with suppressed stray capacity | |
| JP2614449B2 (en) | Insulation resistance measurement method compensated for ground resistance | |
| JP2696513B2 (en) | Electrical capacitance measurement method for ground | |
| JP2750690B2 (en) | Leakage current detection method | |
| JPH0458582B2 (en) | ||
| JP2929197B2 (en) | Insulation resistance measurement method that compensates for the effect of ground resistance | |
| JP2612719B2 (en) | Simple insulation resistance measurement method for electrical circuits | |
| JP3183450B2 (en) | Wiring current route search method | |
| JP2614447B2 (en) | Insulation resistance measurement method that compensates for the effect of ground resistance | |
| JPH0721523B2 (en) | Insulation resistance measurement method that compensates for fluctuations in circuit constants | |
| JPH0812216B2 (en) | Method for measuring insulation resistance of two electric circuits | |
| JP2681187B2 (en) | Insulation fault location search method | |
| JPH0467631B2 (en) | ||
| JP2750716B2 (en) | Insulation resistance measurement method for low voltage wiring etc. | |
| JP2750707B2 (en) | Insulation resistance measurement method compensated for ground resistance |