JP3716308B2

JP3716308B2 - High resistance measuring method and high resistance measuring apparatus

Info

Publication number: JP3716308B2
Application number: JP2002315162A
Authority: JP
Inventors: 英文西中
Original assignee: National Institute of Advanced Industrial Science and Technology AIST
Current assignee: National Institute of Advanced Industrial Science and Technology AIST
Priority date: 2002-10-30
Filing date: 2002-10-30
Publication date: 2005-11-16
Anticipated expiration: 2022-10-30
Also published as: JP2004150902A

Description

【０００１】
【発明の属する技術分野】
本発明は、高抵抗測定方法および高抵抗測定装置に関し、特にツェナー標準電圧発生器の端子−ケース間絶縁抵抗のような、１０^１０〜１０^１４Ω程度の極めて高い抵抗値を有する抵抗体の抵抗値の測定方法と測定装置に関するものである。
【０００２】
【従来の技術】
現在、製造メーカ等において行われる計測器や電圧計の校正には、図５に示すような、電圧値が正確に知られているツェナー標準電圧発生器が用いられている。図５において、Ｅ１、Ｅ２は、電圧源、Ｒ１〜Ｒ９は抵抗器、ＺＤはツェナーダイオード、１は電圧制御回路、２は増幅器、３はツェナー標準電圧発生器のケースである。この標準電圧発生器において、増幅器２の二つの入力端子間の電圧差がなくなるように回路を動作させて定電圧を発生させ、端子Ｌを基準電位端子として、端子Ｈから例えば１０Ｖが、端子Ｔ１から例えば１．０１８Ｖが、端子Ｔ２から例えば１．０Ｖが得られるようになっている。このツェナー標準電圧発生器のユーザは、被校正電子機器、例えば電圧計の２端子をツェナー標準電圧発生器の端子Ｌと例えば端子Ｈに接続して校正を行う。このとき、ツェナー標準電圧発生器の電圧値は、この絶縁抵抗Ｒｘの大きさによって、その値が変化してしまう。したがって、絶縁抵抗の値を正確に測定して誤差の大きさを明確にしないと、計測器や電圧計の校正が不正確となってしまう。而して、この絶縁抵抗の測定は、一般に容易ではない。それは、この絶縁抵抗が極めて高抵抗であることと、回路上、いたるところに存在する、漏れ電流の影響を除去しなければならないことによる。
【０００３】
この種の抵抗値を測定する技術としては、従来から微小電流測定法が一般的に用いられている。この方法は、図６に示すように、既知の電圧値Eと絶縁抵抗Rxを流れる微小電流Iを電流計Aで求めて、Rx=E/Iとして算出する方法である。このとき、図６に示すように、絶縁物の表面や内部を通過して漏れ電流と呼ばれるIrgとIegが流れる。Irgは、余分の電流として電流計に流れるため、絶縁抵抗Rxを流れる電流Iの測定値に影響を及ぼし、また、Iegは、電源から余分の電流をとるため電圧値Eの値を下げてしまう。これを防ぐには、内部抵抗の小さい電源を使用し、図７に示すように、シールドと呼ばれる遮蔽板4を設けることが一般的に行われている。通常、この遮蔽板4によって、漏れ電流Irgは、外側のシールドを流れることとなり電流計を通過しないため正確な測定ができるようになる。
また、抵抗測定法としては、被測定抵抗器を１辺とするホイートストン・ブリッジを組み、ブリッジの平衡条件を求めることにより抵抗値を測定する方法がある。
【０００４】
【発明が解決しようとする課題】
図６に示す従来の測定法を、図５に示すような、ツェナー標準電圧発生器の測定端子とケース間との絶縁抵抗Rxの測定に使用すると、図８に示すように、外側のケース部分が電流計の測定端子に接続されるため、電気回路の正電圧部分からケースに対して漏れ電流Irgが流れる。この漏れ電流は当然、余分の電流として電流計に流れるため測定値に影響を及ぼす。これには、シールドを施すのが有効であるが、ツェナー標準電圧発生器をシールドするためには、図９に示すように、ケース全体と測定端子を絶縁材料5でおおってから遮蔽板4を設けなければならず、極めて複雑なシールドとなってしまう。
また、ホイートストン・ブリッジの平衡条件により抵抗値を求める方法では、絶縁抵抗のような高抵抗を測定するためには被測定抵抗以外の辺に絶縁抵抗に匹敵する高抵抗の抵抗器を接続しなければならないが、そのような高抵抗の抵抗器の抵抗値を正確に求めることは一般に困難である。また、安定な高抵抗の抵抗器を得ることも容易ではない。
本発明の課題は、上述した従来技術の問題点を解決することであって、その目的は、第１に、高抵抗を用いることなく高抵抗測定用のブリッジを構成することができるようにすることであり、第２に、複雑なシールドを用いることなく漏れ電流の影響を除去することであって、もって高抵抗抵抗体の抵抗値を高い精度において測定できるようにすることである。
【０００５】
【課題を解決するための手段】
上記の目的を達成するため、本発明によれば、第１、第２、第３点のそれぞれに３抵抗器の一端が接続されるとともに３抵抗器の他端が共通接続されるようにして該３抵抗器により第１の抵抗Ｙ回路を構成し、第２点‐第３点間に比例辺の抵抗器を、第４点‐第１点間に被測定抵抗を、第４点‐第３点間に基準抵抗を、第１点‐第３点間に電源を接続し、第４点を接地電位となるように回路を平衡させた後、第２点と第４点とを平衡させることにより被測定抵抗の抵抗値を求めることを特徴とする高抵抗測定方法、が提供される。
そして、好ましくは、抵抗Ｙ回路を構成する抵抗器の内、第１点に接続される抵抗器が第１の可変抵抗回路により構成される。
【０００６】
また、上記の目的を達成するため、本発明によれば、第１、第２、第３点のそれぞれに３抵抗器の一端が接続されるとともに３抵抗器の他端が共通接続されるようにして該３抵抗器により第１の抵抗Ｙ回路を構成し、第２点‐第３点間に比例辺の抵抗器を、第４点‐第１点間に被測定抵抗を、第４点‐第３点間に基準抵抗を、第１点‐第３点間に電源を、第４点に平衡検出器の一端を接続し、該平衡検出器の他端を第２点と接地点とに切り替え接続できるように構成し、第４点を接地電位となるように回路を平衡させた後、第２点と第４点とを平衡させることにより被測定抵抗の抵抗値を求めることを特徴とする高抵抗測定装置、が提供される。
そして、好ましくは、接地点、第１点および第３点のそれぞれに３抵抗器の一端が接続されるようにして該３抵抗器により第２の抵抗Ｙ回路を構成する。
【０００７】
【作用】
本発明においては、Y-Δ変換型のブリッジ回路を用いて抵抗測定を行う。比較的低抵抗の抵抗器を用いた抵抗Y回路であってもY-Δ変換により等価的に高抵抗を得ることができるため、低抵抗な抵抗器を用いて高抵抗測定用ブリッジを構成することが可能になる。さらに、Y-Δ変換型の接地装置を用いて等価的にブリッジ回路の１点を接地することによりブリッジ回路に存在する漏れ電流の除去を行う。この方法によれば、外側のケースが等価的に接地電位となるため、ケースと測定端子を絶縁材料でおおうことなく、外側のケースを遮蔽板として兼用できる。そして、この方法により、Y-Δ変換型の接地装置のもつ低抵抗回路による漏れ電流の補償が可能となる。
【０００８】
【発明の実施の形態】
図１は、本発明の一実施例を示す回路図である。図１において、上半分の回路は抵抗値測定用の主回路であり、下半分の回路は接地装置を構成する回路である。図１において、Rao、RboおよびRcoは、O点を中心として、a点、b点およびc点間にY接続される比較的低抵抗の抵抗器、Rxは、a点‐d点間に接続される、被測定抵抗器であるツェナー標準電圧発生器の絶縁抵抗、Rsとrsは、c点‐d点間に接続される、値が既知の基準抵抗器、R1とr1は、ｂ点‐c点間に接続される、比例辺の抵抗器、Dは平衡検出用の検出器であって、その一端はd点に接続され、その他端はスイッチSWを介してb点と接地点に切り替えし接続されるようになっている。
Rw2とrw2、Rw3およびRw4は、a点、c点およびe点間にY接続されて第２のY回路を構成する抵抗器、Rw1とrw1は、c点‐e点間に接続される、比例辺の抵抗器、Eは電圧源である。e点は、接地されている。Rw1、rw1、Rw2、rw2、Rw3およびRw4は、漏れ電流の影響を除去するためのY-Δ変換型の接地装置を構成している。
【０００９】
上記抵抗器のうち、抵抗器Rao、rs、Rw4およびrw2は可変抵抗器であって、Rao、rsは主回路のブリッジを平衡させるために用いる補償回路を、Rw4、rw2は漏れ抵抗との平衡をとるための補償回路を構成している。図２（ａ）、（ｂ）は抵抗器Raoと抵抗器rsの可変範囲を示す。補償回路１の補償抵抗器Raoは、４個の可変抵抗器からなり各レンジの可変範囲は、1kΩ〜10kΩ、次に、10kΩ〜100kΩ、100kΩ〜1MΩ、最後に、1MΩ〜10MΩとなる。つまり、1kΩ〜10MΩまでの任意の値を設定することができる。補償回路２の抵抗器rsは、3個の可変抵抗器からなり各レンジの可変範囲は、100Ω〜1kΩ、次に、1kΩ〜10kΩ、最後に、10kΩ〜100kΩとなる。ただし、Rsは100kΩである。
接地装置の可変抵抗器Rw4とrw2は、Rw4がRaoに、またrw2がrsに対応しており、それぞれの可変範囲は図２（ａ）、（ｂ）に示すとおりである。
【００１０】
Rao、RboおよびRcoによって構成されるY型回路は、等価的に抵抗器R2、RacおよびRcbのΔ型回路を形成している。ここで、Rao、Rbo≫Rcoに設定されている。この条件で、特に、ブリッジの比例辺の一辺となる抵抗器R2は等価的に極めて高い抵抗器となる。抵抗器R1も同様に比例辺の一辺となるが、Y-Δ変換による抵抗Rcbが並列に加わると、その並列抵抗値はR1の公称値からずれるため調整用の抵抗器r1を直列接続してある。
【００１１】
Y-Δ変換により等価抵抗値R2は、次式となる。
R2＝Rao+Rbo+Rao・Rbo/Rco [Ω] (1)
となる。ここで、Rao・Rbo/Rco≫Rao、Rboであるので、
R2≒Rao・Rbo/Rco [Ω] (１′)
(1′)式より、R2は等価的に高抵抗となる。このR2を用いると絶縁抵抗Rxは、
Rx=(Rs＋rs)・R2/Rp [Ω] (2)
となる。ただしRpは、Rp=(R1+r1)・Rcb/（R1+r1+Rcb）である。(2)式から、絶縁抵抗Rxの値によって等価抵抗R2の大きさが決まることになる。つまり、(1′)式の補償抵抗器Raoの設定値が決定される。このとき、例えば、可変範囲の最大値10MΩを設定値とすると、残りの三つの可変抵抗器で、上位からあと３桁を設定できるが、最小値１ｋΩを設定値とすると、数値は上位から１桁のみとなってしまう。このような問題点を解決するために、補償回路２を別途用いることにした。つまり、最上位の桁は、補償抵抗器Raoのみで求めておいて、その次の桁からは、補償抵抗器rsを用いる。この手法は、(1′)式と(2)式からも原理的に可能なことが明らかである。この補償方法を用いることにより、任意の絶縁抵抗値を1/1000の桁まで求めることが可能となった。ただし、測定精度は、１％程度であると推定される。
同様に、可変抵抗器Rw4は上１桁を設定するのに使用され、可変抵抗器rw2は上位からあと３桁を設定するのに用いられる。
【００１２】
以下に測定手順を述べる。まず始めにスイッチSWを接地側にし、検出器Dを接地する。このときのブリッジ構成は図３のようになる。漏れ電流の原因となる漏れ抵抗Rh1およびRh2は、すべて接地装置側の対地電位であるe点に集中して分布するようになり、見かけ上、接地装置の一部であるかのように構成される。この状態において、ブリッジ回路が平衡するように補償抵抗器Rw4とrw2を調整する。平衡時における検出器Dの両端e点とd点は同電位となる。次に、スイッチSWを切り替えて、検出器Dをb点側にすると、ブリッジ構成は図４のようになる。この主回路を用いて、ツェナー標準電圧発生器の絶縁抵抗測定を実施する。ｄ点は見かけ上、対地から浮いた状態になっているが、前の平衡操作により、等価的に対地電位を保持しているため、ツェナー標準電圧発生器のケースは強制的に対地電位となり、遮蔽板の役割を果たすことになる。主回路の平衡は、補償抵抗器Rao、rsを調整して得、検出器Dで検出する。このときの平衡条件式は(1′)式と(2)式から、次式となる。
Rx=(Rs+rs)・RaoRbo/RcoRp [Ω] (3)
ここで、Rbo=100kΩ、Rp=1kΩおよびRco=1Ωと選定しているものとすると、Rbo/Rp・Rco=10^２となる。これより(3)式は、
Rx=(Rs+rs)Rao×10^２ [Ω] (4)
で与えられる。よって、ツェナー標準電圧発生器の絶縁抵抗Rxが求められることになる。
【００１３】
なお、rsを調節することにより、主回路と接地装置との平衡が崩れることになる。したがって、rsがRsに比較して大きく、主回路の調整時にrsの可変量が大きい場合には再度ｄ点を接地電位に調整した後に再び主回路の平衡条件を求める必要がある。rsがRsに比較して小さい場合やrsの変化量が小さい場合には再調整を行わなくても十分高い精度の測定が可能である。
【００１４】
以上好ましい実施例について説明したが、本発明は上記の実施例に限定されるものではなく、本発明の要旨を逸脱しない範囲内において適宜の変更が可能なものである。たとえば、抵抗器Rao、rsは、必ずしも４個ないし３個の可変抵抗器によって構成するのではなく他の個数であっても良く、またその可変範囲も実施例のとおりである必要はない。また、抵抗器Rw4、rw２の可変範囲は抵抗器Rao、rsのそれと同じである必要はない。また、本発明はツェナー標準電圧発生器の絶縁抵抗の測定に有利に用いられるが、この用途に限定されず、他の標準器や計測器の絶縁抵抗やその他の高抵抗の測定にも適用できる。
【００１５】
【発明の効果】
以上説明したように、本発明は、Y-Δ変換型の主回路ブリッジを用いて絶縁抵抗のような高抵抗の値を測定するものであるので、低抵抗を用いたY型回路により、10¹⁰〜10¹⁴Ω程度の高抵抗を上位３桁程度の高い精度をもって測定することができる。また、Y-Δ変換型の接地装置を用いて、主回路ブリッジの１点を等価的に接地することにより、回路的に接地から浮いた主回路に係る漏れ電流の影響を低抵抗の補償回路をもつ接地装置で除去することができる。
【図面の簡単な説明】
【図１】本発明の一実施例を示す回路図。
【図２】抵抗器Raoと抵抗器rsの構成を説明するための図。
【図３】本発明の一実施例の動作説明図（その１）。
【図４】本発明の一実施例の動作説明図（その２）。
【図５】ツェナー標準電圧発生装置の概略の構成を示す図。
【図６】従来の抵抗測定方法を示す図（その１）。
【図７】従来の抵抗測定方法を示す図（その２）。
【図８】従来例の問題点を説明するための図（その１）。
【図９】従来例の問題点を説明するための図（その２）。
【符号の説明】
１電圧制御回路
２増幅器
３ケース
４遮蔽板
５絶縁材料[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high resistance measurement method and a high resistance measurement device, and more particularly, resistance of a resistor having an extremely high resistance value of about 10 ¹⁰ to 10 ¹⁴ Ω, such as a terminal-case insulation resistance of a Zener standard voltage generator. The present invention relates to a value measuring method and a measuring apparatus.
[0002]
[Prior art]
At present, a Zener standard voltage generator whose voltage value is accurately known as shown in FIG. 5 is used for calibration of a measuring instrument or a voltmeter performed by a manufacturer or the like. In FIG. 5, E1 and E2 are voltage sources, R1 to R9 are resistors, ZD is a Zener diode, 1 is a voltage control circuit, 2 is an amplifier, and 3 is a case of a Zener standard voltage generator. In this standard voltage generator, the circuit is operated so as to eliminate the voltage difference between the two input terminals of the amplifier 2 to generate a constant voltage. For example, 10 V from the terminal H is applied to the terminal T1 using the terminal L as a reference potential terminal. For example, 1.018V is obtained from the terminal T2, and for example 1.0V is obtained from the terminal T2. The user of the Zener standard voltage generator performs calibration by connecting two terminals of an electronic device to be calibrated, for example, a voltmeter to a terminal L of the Zener standard voltage generator and, for example, a terminal H. At this time, the voltage value of the Zener standard voltage generator changes depending on the magnitude of the insulation resistance Rx. Therefore, unless the value of the insulation resistance is accurately measured and the magnitude of the error is not clarified, the calibration of the measuring instrument or the voltmeter becomes inaccurate. Thus, it is generally not easy to measure the insulation resistance. This is because the insulation resistance is extremely high, and the influence of leakage current that exists everywhere in the circuit must be removed.
[0003]
As a technique for measuring this type of resistance value, a minute current measurement method has been generally used. As shown in FIG. 6, this method is a method in which a minute current I flowing through a known voltage value E and an insulation resistance Rx is obtained by an ammeter A and calculated as Rx = E / I. At this time, as shown in FIG. 6, Irg and Ieg called leakage currents flow through the surface and the inside of the insulator. Since Irg flows to the ammeter as an extra current, it affects the measured value of the current I flowing through the insulation resistance Rx, and Ieg takes the extra current from the power supply and lowers the voltage value E. . In order to prevent this, it is common practice to use a power supply with a small internal resistance and to provide a shielding plate 4 called a shield as shown in FIG. Normally, the shielding plate 4 allows the leakage current Irg to flow through the outer shield and does not pass through the ammeter so that accurate measurement can be performed.
Further, as a resistance measuring method, there is a method of measuring a resistance value by assembling a Wheatstone bridge with one side of the resistor to be measured and obtaining an equilibrium condition of the bridge.
[0004]
[Problems to be solved by the invention]
When the conventional measurement method shown in FIG. 6 is used to measure the insulation resistance Rx between the measurement terminal of the Zener standard voltage generator and the case as shown in FIG. 5, the outer case portion is shown in FIG. Is connected to the measurement terminal of the ammeter, so that a leakage current Irg flows from the positive voltage portion of the electric circuit to the case. This leakage current naturally flows through the ammeter as an extra current, which affects the measured value. For this purpose, shielding is effective, but in order to shield the Zener standard voltage generator, as shown in FIG. 9, the entire case and measurement terminals are covered with an insulating material 5, and then the shielding plate 4 is covered. It must be provided and it becomes a very complicated shield.
In addition, in the method of obtaining the resistance value according to the Wheatstone bridge equilibrium condition, in order to measure a high resistance such as an insulation resistance, a high resistance resistor equivalent to the insulation resistance must be connected to a side other than the resistance to be measured. However, it is generally difficult to accurately determine the resistance value of such a high resistance resistor. It is also not easy to obtain a stable high resistance resistor.
An object of the present invention is to solve the above-described problems of the prior art, and the object of the present invention is to firstly configure a bridge for high resistance measurement without using high resistance. Secondly, the influence of the leakage current is eliminated without using a complicated shield, and the resistance value of the high resistance resistor can be measured with high accuracy.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, one end of the three resistors is connected to each of the first, second, and third points, and the other ends of the three resistors are commonly connected. The first resistor Y circuit is constituted by the three resistors, the resistor of the proportional side between the second point and the third point, the resistance to be measured between the fourth point and the first point, and the fourth point to the second point. Connect the reference resistor between the three points, connect the power supply between the first point and the third point , balance the circuit so that the fourth point becomes the ground potential, and then balance the second point and the fourth point Thus , there is provided a high resistance measuring method characterized in that a resistance value of a resistance to be measured is obtained.
Preferably, the resistor connected to the first point among the resistors constituting the resistor Y circuit is configured by the first variable resistor circuit.
[0006]
In order to achieve the above object, according to the present invention, one end of the three resistors is connected to each of the first, second, and third points, and the other ends of the three resistors are commonly connected. The first resistor Y circuit is constituted by the three resistors, the resistor on the proportional side between the second point and the third point , the resistance to be measured between the fourth point and the first point, and the fourth point. -Connect the reference resistor between the third point, the power source between the first point-the third point, and connect one end of the balanced detector to the fourth point, and connect the other end of the balanced detector to the second point and the ground point The resistance value of the resistance to be measured is obtained by balancing the second point and the fourth point after balancing the circuit so that the fourth point becomes the ground potential. A high resistance measuring device is provided.
Preferably, one end of a three resistor is connected to each of the ground point, the first point, and the third point, and the second resistor Y circuit is configured by the three resistors.
[0007]
[Action]
In the present invention, resistance measurement is performed using a Y-Δ conversion type bridge circuit. Even in a resistance Y circuit using a relatively low resistance resistor, a high resistance can be obtained equivalently by Y-Δ conversion, so a high resistance measurement bridge is configured using a low resistance resistor. It becomes possible. Furthermore, the leakage current existing in the bridge circuit is removed by equivalently grounding one point of the bridge circuit using a Y-Δ conversion type grounding device. According to this method, since the outer case is equivalently grounded, the outer case can be used as a shielding plate without covering the case and the measurement terminal with an insulating material. By this method, the leakage current can be compensated by the low resistance circuit of the Y-Δ conversion type grounding device.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a circuit diagram showing an embodiment of the present invention. In FIG. 1, the upper half circuit is a main circuit for measuring a resistance value, and the lower half circuit is a circuit constituting a grounding device. In FIG. 1, Rao, Rbo and Rco are Y resistors connected between points a, b and c with O point as the center, and Rx is connected between points a and d The insulation resistance of the Zener standard voltage generator, which is the resistor to be measured, Rs and rs are connected between the point c and the point d, the reference resistor having a known value, and the points R1 and r1 are the points b A proportional-side resistor connected between points c, D is a detector for balanced detection, one end of which is connected to point d, and the other end is switched to point b and ground via switch SW. And connected.
Rw2 and rw2, Rw3 and Rw4 are Y-connected between points a, c and e to form a second Y circuit, and Rw1 and rw1 are connected between points c and e. A proportional-side resistor, E, is a voltage source. Point e is grounded. Rw1, rw1, Rw2, rw2, Rw3, and Rw4 constitute a Y-Δ conversion type grounding device for removing the influence of leakage current.
[0009]
Of the above resistors, resistors Rao, rs, Rw4 and rw2 are variable resistors, Rao and rs are compensation circuits used to balance the bridge of the main circuit, and Rw4 and rw2 are balanced with leakage resistance. The compensation circuit for taking this is configured. 2A and 2B show variable ranges of the resistor Rao and the resistor rs. The compensation resistor Rao of the compensation circuit 1 is composed of four variable resistors, and the variable range of each range is 1 kΩ to 10 kΩ, then 10 kΩ to 100 kΩ, 100 kΩ to 1 MΩ, and finally 1 MΩ to 10 MΩ. That is, an arbitrary value from 1 kΩ to 10 MΩ can be set. The resistor rs of the compensation circuit 2 includes three variable resistors, and the variable range of each range is 100Ω to 1kΩ, then 1kΩ to 10kΩ, and finally 10kΩ to 100kΩ. However, Rs is 100 kΩ.
In the variable resistors Rw4 and rw2 of the grounding device, Rw4 corresponds to Rao and rw2 corresponds to rs. The variable ranges are as shown in FIGS. 2 (a) and 2 (b).
[0010]
A Y-type circuit constituted by Rao, Rbo and Rco equivalently forms a Δ-type circuit of resistors R2, Rac and Rcb. Here, Rao, Rbo >> Rco are set. Under this condition, in particular, the resistor R2 which is one side of the proportional side of the bridge is equivalently a very high resistor. Resistor R1 also becomes one side of the proportional side in the same way, but if resistor Rcb due to Y-Δ conversion is added in parallel, the parallel resistance value will deviate from the nominal value of R1, so resistor R1 for adjustment is connected in series. is there.
[0011]
The equivalent resistance value R2 is expressed by the following equation by Y-Δ conversion.
R2 ＝ Rao + Rbo + Rao ・ Rbo / Rco [Ω] (1)
It becomes. Here, Rao / Rbo / Rco >> Rao, Rbo,
R2 ≒ Rao ・ Rbo / Rco [Ω] (1 ')
From equation (1 ′), R2 is equivalently high resistance. Using this R2, the insulation resistance Rx is
Rx = (Rs + rs) ・ R2 / Rp [Ω] (2)
It becomes. However, Rp is Rp = (R1 + r1) · Rcb / (R1 + r1 + Rcb). From equation (2), the magnitude of the equivalent resistance R2 is determined by the value of the insulation resistance Rx. That is, the set value of the compensation resistor Rao in the equation (1 ′) is determined. At this time, for example, if the maximum value of 10 MΩ in the variable range is set as the set value, the remaining three variable resistors can set the remaining 3 digits from the top, but if the minimum value is 1 kΩ, the value is 1 from the top. It becomes only digits. In order to solve such a problem, the compensation circuit 2 is separately used. That is, the most significant digit is obtained only by the compensation resistor Rao, and the compensation resistor rs is used from the next digit. It is clear that this method is theoretically possible from the equations (1 ') and (2). By using this compensation method, it is possible to obtain an arbitrary insulation resistance value up to 1/1000 order. However, the measurement accuracy is estimated to be about 1%.
Similarly, the variable resistor Rw4 is used to set the first digit, and the variable resistor rw2 is used to set the remaining three digits from the top.
[0012]
The measurement procedure is described below. First, the switch SW is set to the ground side, and the detector D is grounded. The bridge configuration at this time is as shown in FIG. The leakage resistances Rh1 and Rh2 that cause the leakage current are all concentrated and distributed at the point e, which is the ground potential on the grounding device side, and are configured as if they are part of the grounding device. The In this state, the compensation resistors Rw4 and rw2 are adjusted so that the bridge circuit is balanced. At the time of equilibrium, both ends e and d of the detector D have the same potential. Next, when the switch SW is switched and the detector D is set to the point b side, the bridge configuration is as shown in FIG. Using this main circuit, the insulation resistance of the Zener standard voltage generator is measured. Although the point d is apparently floating from the ground, since the ground potential is equivalently held by the previous equilibrium operation, the case of the Zener standard voltage generator is forced to the ground potential, It will serve as a shielding plate. The balance of the main circuit is obtained by adjusting the compensation resistors Rao and rs and is detected by the detector D. The equilibrium condition formula at this time becomes the following formula from the formulas (1 ′) and (2).
Rx = (Rs + rs) ・ RaoRbo / RcoRp [Ω] (3)
Here, Rbo = 100kΩ, if it is assumed that the selection and Rp = 1 k [Omega and Rco = 1 [Omega, the ^{Rbo / Rp · Rco = 10 2} . From this, equation (3) becomes
Rx = (Rs + rs) Rao × 10 ² [Ω] (4)
Given in. Therefore, the insulation resistance Rx of the Zener standard voltage generator is obtained.
[0013]
By adjusting rs, the balance between the main circuit and the grounding device is lost. Therefore, if rs is larger than Rs and the variable amount of rs is large during adjustment of the main circuit, it is necessary to obtain the equilibrium condition of the main circuit again after adjusting point d to the ground potential again. When rs is smaller than Rs or when the amount of change in rs is small, sufficiently high-precision measurement can be performed without readjustment.
[0014]
Although the preferred embodiments have been described above, the present invention is not limited to the above-described embodiments, and appropriate modifications can be made without departing from the scope of the present invention. For example, the resistors Rao and rs are not necessarily constituted by four to three variable resistors, but may be other numbers, and the variable range thereof does not have to be as in the embodiment. Further, the variable range of the resistors Rw4 and rw2 need not be the same as that of the resistors Rao and rs. Further, the present invention is advantageously used for measuring the insulation resistance of a Zener standard voltage generator, but is not limited to this application, and can be applied to the measurement of insulation resistance of other standard devices and measuring instruments and other high resistances. .
[0015]
【The invention's effect】
As described above, the present invention measures a high resistance value such as an insulation resistance by using a Y-Δ conversion type main circuit bridge. A high resistance of about ¹⁰ to 10 ¹⁴ Ω can be measured with high accuracy of the upper three digits. Also, by using a Y-Δ conversion type grounding device, one point of the main circuit bridge is equivalently grounded, so that the effect of leakage current on the main circuit floating from the ground in terms of circuit is compensated for by a low resistance. It can be removed with a grounding device having
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of the present invention.
FIG. 2 is a diagram for explaining a configuration of a resistor Rao and a resistor rs.
FIG. 3 is a diagram for explaining the operation of an embodiment of the present invention (No. 1).
FIG. 4 is a diagram for explaining the operation of the embodiment of the present invention (No. 2).
FIG. 5 is a diagram showing a schematic configuration of a Zener standard voltage generator.
FIG. 6 is a diagram showing a conventional resistance measuring method (No. 1).
FIG. 7 is a diagram showing a conventional resistance measuring method (No. 2).
FIG. 8 is a diagram (part 1) for explaining problems of the conventional example.
FIG. 9 is a diagram (part 2) for describing problems of the conventional example.
[Explanation of symbols]
1 Voltage Control Circuit 2 Amplifier 3 Case 4 Shielding Plate 5 Insulating Material

Claims

The first resistor Y circuit is configured by the three resistors such that one end of the three resistors is connected to each of the first, second, and third points and the other ends of the three resistors are commonly connected. , A proportional side resistor between the second point and the third point, a resistance to be measured between the fourth point and the first point, a reference resistance between the fourth point and the third point, and a first point to the third point connect the power between the points, after the fourth point to balance the circuit so that the ground potential, wherein the determination of the resistance value of the measured resistance by Rukoto equilibrated second point and a fourth point High resistance measurement method.

2. The high resistance measuring method according to claim 1, wherein a resistor connected to the first point among the resistors constituting the first resistor Y circuit is constituted by a first variable resistor circuit. .

The high resistance measuring method according to claim 2, wherein the variable range of the first variable resistance circuit is four digits.

4. The high resistance measuring method according to claim 1, wherein a resistance value of the reference resistor is variable.

The resistance value of the reference resistor is variable in a range of R to 2.111R (where R is an arbitrary resistance value of 10 kΩ to 1 MΩ), and its minimum variable width is R / 1000. Item 5. The high resistance measurement method according to Item 4.

6. The high resistance measuring method according to claim 1, wherein the first auxiliary resistor is connected between the second point and the third point.

7. The high resistance measurement method according to claim 1, wherein the measurement is performed by adjusting the potential of the fourth point to the ground potential without grounding the fourth point.

The first resistor Y circuit is configured by the three resistors such that one end of the three resistors is connected to each of the first, second, and third points and the other ends of the three resistors are commonly connected. , A proportional side resistor between the second point and the third point, a resistance to be measured between the fourth point and the first point, a reference resistance between the fourth point and the third point, and a first point to the third point power between the points, to connect one end of the balanced detector to the fourth point, the other end of the balance detector configured to be switched connected to the ground point and the second point, and the fourth point ground potential A high resistance measuring apparatus characterized by obtaining a resistance value of a resistance to be measured by balancing a second point and a fourth point after the circuit is balanced in such a manner .

9. The high resistance measuring device according to claim 8, wherein a resistor connected to the first point among the resistors constituting the first resistor Y circuit is constituted by a first variable resistor circuit. .

The high resistance measuring device according to claim 9, wherein the first variable resistance circuit includes a plurality of variable resistors having different variable ranges.

11. The reference resistor is constituted by a reference fixed resistor and a second variable resistor circuit, and a variable range of the second variable resistor circuit is about the resistance value of the reference fixed resistor. The high resistance measuring device according to any one of the above.

The high resistance measuring apparatus according to claim 11, wherein the second variable resistance circuit includes a plurality of variable resistors having different variable ranges.

The high resistance measuring device according to claim 8, wherein a first auxiliary resistor is connected between the second point and the third point.

The high resistance measuring apparatus according to claim 13, wherein the first auxiliary resistor includes two fixed resistors.

15. The second resistor Y circuit is constituted by the three resistors so that one end of each of the three resistors is connected to the ground point, the first point, and the third point, respectively. The high resistance measuring device according to any one of the above.

16. The high resistance measuring device according to claim 15, wherein a resistor connected to the first point of the resistors constituting the second resistor Y circuit is constituted by a third variable resistor circuit. .

The high resistance measuring device according to claim 16, wherein the third variable resistance circuit includes a plurality of variable resistors having different variable ranges.

Among the resistors constituting the second resistor Y circuit, the resistor connected to the ground point is constituted by a ground circuit fixed resistor and a fourth variable resistor circuit, and the variable range of the fourth variable resistor circuit is The high resistance measuring device according to claim 15, wherein the high resistance measuring device is about a resistance value of the ground circuit fixed resistor.

19. The high resistance measuring device according to claim 18, wherein the fourth variable resistance circuit includes a plurality of variable resistors having different variable ranges.

The high resistance measuring device according to claim 15, wherein a second auxiliary resistor is connected between the ground point and the third point.

21. The high resistance measuring device according to claim 20, wherein the second auxiliary resistor is constituted by two fixed resistors.