JP2006343267A

JP2006343267A - Insulation resistance measuring instrument of dc circuit, electrostatic capacitance measuring instrument, insulation resistance measuring method and electrostatic capacitance measuring method

Info

Publication number: JP2006343267A
Application number: JP2005170688A
Authority: JP
Inventors: Ten Kusaka; 天日下; Mitsuhiro Nonogami; 満洋野々上; Susumu Kawahigashi; 進川東; Eiji Nishiyama; 英治西山; Minoru Matsumura; 稔松村; Sohei Takaoka; 宗平高岡
Original assignee: Chugoku Electric Power Co Inc
Current assignee: Chugoku Electric Power Co Inc
Priority date: 2005-06-10
Filing date: 2005-06-10
Publication date: 2006-12-21

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and easily measure an insulation resistance and an electrostatic capacitance of a DC circuit to the ground in a live-wire state. <P>SOLUTION: A ground resistors 3 is grounded at the positive/negative terminal of the DC circuit D. A stable voltage value for stabilizing a voltage between terminals of the ground resistor 3 is measured at the positive/negative terminal. The insulation resistances Rp, Rn are calculated, based on the stable voltage values. A transition duration (time constant) is measured, until the voltage between the terminals of the ground resistor 3 reaches a predetermined voltage. The electrostatic capacitance (Cp+Cn) is calculated, based on the transition duration and the insulation resistances Rp, Rn. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、電気所などにおける直流電源系統の直流回路の対地絶縁抵抗値を活線状態（運用状態）のままで測定することができる測定器と測定方法とに関し、さらに、直流回路の対地静電容量値を測定することができる測定器と測定方法とに関する。 The present invention relates to a measuring instrument and a measuring method capable of measuring a ground insulation resistance value of a direct current circuit of a direct current power supply system in an electric power station or the like in a live line state (operating state). The present invention relates to a measuring instrument capable of measuring a capacitance value and a measuring method.

直流電源系統の絶縁劣化に伴う電力機器への障害などを予防するために、直流回路の対地絶縁抵抗値を測定する必要がある。従来、この絶縁抵抗値を測定する場合、すべての直流回路を停電させることが実務上不可能であるため、定期点検などで停電させた箇所を部分的に測定していた。このため、直流回路全体の絶縁抵抗値を把握できないのが実情であった。このような実情から、直流回路の対地絶縁抵抗値を活線状態のままで測定できる方法や測定器の確立が望まれており、そのような絶縁抵抗計も知られている（例えば、特許文献１参照。）。この絶縁抵抗計は、直流回路の正極側と大地間および、負極側と大地間に切換開閉器を介して漏洩電流計が設けられ、この漏洩電流計によって、正極側対大地間絶縁抵抗または負極側対大地間絶縁抵抗を流れる漏洩電流を測定する。そして、測定された漏洩電流と直流電圧とから絶縁抵抗値を演算するものである。 It is necessary to measure the ground insulation resistance value of a DC circuit in order to prevent a failure to power equipment due to insulation deterioration of the DC power supply system. Conventionally, when measuring this insulation resistance value, it is impossible in practice to power out all DC circuits, and therefore, a part where power is interrupted in a periodic inspection or the like has been partially measured. For this reason, the actual situation is that the insulation resistance value of the entire DC circuit cannot be grasped. From such a situation, it is desired to establish a method and a measuring instrument that can measure the insulation resistance value of a DC circuit with a live line state, and such an insulation resistance meter is also known (for example, patent document) 1). This insulation resistance meter is provided with a leakage ammeter through a switching switch between the positive electrode side and the ground of the DC circuit and between the negative electrode side and the ground. Measure the leakage current flowing through the side-to-ground insulation resistance. Then, the insulation resistance value is calculated from the measured leakage current and DC voltage.

また、地絡による被害の軽減とその波及の防止とを図るために、直流制御回路地絡継電器（日本電機工業会規格の６４Ｄ）などの地絡継電器を設け、この地絡継電器によって地絡を検出し、遮断器を動作させる方法もとられている。
特開平７−６３８０１号公報 In addition, in order to reduce damage caused by ground faults and prevent their spread, ground fault relays such as DC control circuit ground fault relays (Japan Electric Industry Association Standard 64D) are provided, and ground faults are provided by these ground fault relays. The method of detecting and operating the circuit breaker is taken.
Japanese Patent Laid-Open No. 7-63801

ところで、上記特許文献１に記載されているような絶縁抵抗計では、対地絶縁抵抗値を活線状態のままで測定できるものの、測定精度が低い場合があり、また、測定のための設計などが必要となる。すなわち、このような絶縁抵抗計では、直流回路の対地絶縁抵抗値が大きな値であるために、漏洩電流が極めて微小かつ不安定なものとなり、このような漏洩電流に基づいて絶縁抵抗値が演算（測定）されると、漏洩電流によっては測定精度が低い（ばらつく）場合がある。また、このような絶縁抵抗計を用いて測定する場合、絶縁抵抗計を測定する直流回路に合わせて設計する必要があり、汎用性が低かった。 By the way, in the insulation resistance meter as described in the above-mentioned Patent Document 1, although the ground insulation resistance value can be measured in a live line state, the measurement accuracy may be low, and the design for the measurement, etc. Necessary. That is, in such an insulation resistance meter, the insulation resistance of the DC circuit is large, so the leakage current becomes extremely small and unstable, and the insulation resistance value is calculated based on the leakage current. When (measured), the measurement accuracy may be low (variable) depending on the leakage current. Moreover, when measuring using such an insulation resistance meter, it was necessary to design according to the DC circuit which measures an insulation resistance meter, and versatility was low.

一方、地絡継電器は継電器単体での地絡検出試験のみが行われており、実際の直流回路（実運用状態）での検出感度については、把握されていないのが実情であった。このため、継電器単体での試験では地絡検出感度が正常であっても、実際の直流回路では検出感度が低下することがあり、正常に地絡を検出できないために大きな事故につながる危険性があった。そして、このような危険性は、継電器の地絡検出感度によるものであるとともに、直流回路の対地静電容量値が把握できていないことによるものであった。 On the other hand, as for the ground fault relay, only the ground fault detection test is performed for the relay alone, and the actual situation is that the detection sensitivity in the actual DC circuit (actual operation state) is not grasped. For this reason, even if the ground fault detection sensitivity is normal in the test with the relay alone, the detection sensitivity may decrease in the actual DC circuit, and there is a risk of causing a serious accident because the ground fault cannot be detected normally. there were. Such danger is due to the ground fault detection sensitivity of the relay and the fact that the ground capacitance value of the DC circuit cannot be grasped.

そこで本発明は、直流回路の対地絶縁抵抗値を活線状態のままで高精度かつ容易に測定することができ、さらに、直流回路の対地静電容量値を測定することができる測定器および測定方法を提供することを目的とする。 Therefore, the present invention can measure the ground insulation resistance value of the DC circuit with high accuracy and easily while in a live state, and can further measure the ground capacitance value of the DC circuit and measurement. It aims to provide a method.

上記目的を達成するために請求項１に記載の発明は、直流回路の対地絶縁抵抗値を測定する絶縁抵抗測定器であって、直流回路の正極側と大地間および負極側と大地間に切換手段を介して切換接続される地絡抵抗と、この地絡抵抗の端末間電圧を測定する電圧測定手段と、この電圧測定手段によって測定された地絡抵抗の安定電圧値に基づいて直流回路の対地絶縁抵抗値を演算する演算部とを有することを特徴としている。
（作用）
直流回路の正極側と大地間に地絡抵抗が接続されると、この地絡抵抗と正極側絶縁抵抗とが並列状態となり、その端末間電圧が安定した値が正極側の安定電圧値となる。同様に、直流回路の負極側と大地間に地絡抵抗が接続されると、この地絡抵抗と負極側絶縁抵抗とが並列状態となり、その端末間電圧が安定した値が負極側の安定電圧値となる。そして、これらの接続回路に基づいて、演算部によって、正極側の安定電圧値、負極側の安定電圧値および、地絡抵抗の抵抗値、直流回路の両極間電圧（電源電圧）値から、正極側絶縁抵抗値と負極側絶縁抵抗値とが演算（測定）される。しかも、直流回路の正／負極側と大地間に地絡抵抗が接続され、その端末間電圧が測定されるだけであるため、直流回路を停電させることなく活線状態のままで測定できる。 In order to achieve the above object, an invention according to claim 1 is an insulation resistance measuring instrument for measuring a ground insulation resistance value of a DC circuit, and switches between a positive side and a ground and a negative side and a ground of the DC circuit. A ground fault resistance that is switched through the means, a voltage measurement means that measures a voltage across the terminal of the ground fault resistance, and a DC circuit based on a stable voltage value of the ground fault resistance measured by the voltage measurement means. It has the calculating part which calculates a ground insulation resistance value, It is characterized by the above-mentioned.
(Function)
When a ground fault resistance is connected between the positive side of the DC circuit and the ground, the ground fault resistance and the positive side insulation resistance are in a parallel state, and the stable voltage between the terminals becomes the stable voltage value on the positive side. . Similarly, when a ground fault resistance is connected between the negative electrode side of the DC circuit and the ground, the ground fault resistance and the negative electrode side insulation resistance are in parallel, and the stable voltage between the terminals is the stable voltage on the negative electrode side. Value. Then, based on these connection circuits, the operation unit calculates from the stable voltage value on the positive electrode side, the stable voltage value on the negative electrode side, the resistance value of the ground fault resistance, and the voltage between both electrodes of the DC circuit (power supply voltage) value. The side insulation resistance value and the negative electrode side insulation resistance value are calculated (measured). In addition, since the ground fault resistance is connected between the positive / negative electrode side of the DC circuit and the ground, and the voltage between the terminals is only measured, the DC circuit can be measured in a live line state without causing a power failure.

請求項２に記載の発明は、請求項１に記載の絶縁抵抗測定器において、地絡抵抗の端末間電圧が所定の電圧に達するまでの過渡時間を測定する計時手段を有し、この計時手段によって測定された過渡時間と演算された対地絶縁抵抗値とに基づいて、演算部が直流回路の対地静電容量値を演算することを特徴としている。
（作用）
例えば、所定の電圧を初期電圧（地絡直前の電圧）の３６．８％に設定することで、過渡時間が時定数となり、時定数＝静電容量×抵抗の関係式に基づいて、演算部によって対地静電容量値が演算される。 A second aspect of the present invention is the insulation resistance measuring instrument according to the first aspect, further comprising time measuring means for measuring a transient time until the voltage between the terminals of the ground fault resistance reaches a predetermined voltage. The calculation unit calculates a ground capacitance value of the DC circuit based on the transient time measured by the above and the calculated ground insulation resistance value.
(Function)
For example, by setting the predetermined voltage to 36.8% of the initial voltage (the voltage just before the ground fault), the transient time becomes a time constant, and the calculation unit is based on the relational expression of time constant = capacitance × resistance. The ground capacitance value is calculated by.

請求項３に記載の発明は、直流回路の対地静電容量値を測定する静電容量測定器であって、直流回路の正極側と大地間または負極側と大地間に接続される地絡抵抗と、この地絡抵抗の端末間電圧を測定する電圧測定手段と、端末間電圧が所定の電圧に達するまでの過渡時間を測定する計時手段と、この計時手段によって測定された過渡時間と地絡抵抗が接続された極性側の対地絶縁抵抗値とに基づいて直流回路の対地静電容量値を演算する演算部とを有することを特徴としている。
（作用）
対地絶縁抵抗値が既知である場合、請求項２に記載の発明と同様にして、計時手段によって測定された過渡時間に基づいて、演算部によって対地静電容量値が演算される。 The invention according to claim 3 is a capacitance measuring instrument for measuring a capacitance value of the DC circuit to ground, and is a ground fault resistance connected between the positive electrode side and the ground or between the negative electrode side and the ground of the DC circuit. Voltage measuring means for measuring the terminal voltage of the ground fault resistance, time measuring means for measuring the transient time until the terminal voltage reaches a predetermined voltage, and the transient time measured by the time measuring means and the ground fault And a calculation unit that calculates a ground capacitance value of the DC circuit based on a ground-side insulation resistance value on the polarity side to which the resistor is connected.
(Function)
When the ground insulation resistance value is known, the ground capacitance value is calculated by the calculation unit based on the transient time measured by the time measuring means, as in the second aspect of the invention.

請求項４に記載の発明は、請求項１から３のいずれかに記載の絶縁抵抗測定器または静電容量測定器において、演算部による演算結果を表示する表示手段を有することを特徴としている。
（作用）
表示手段によって演算結果、すなわち、直流回路の対地絶縁抵抗値と対地静電容量値とが表示されるため、目視によって測定（演算）結果を迅速かつ容易に認識できる。 According to a fourth aspect of the present invention, in the insulation resistance measuring device or the capacitance measuring device according to any one of the first to third aspects, there is provided display means for displaying a calculation result by the calculation unit.
(Function)
Since the calculation means, that is, the ground insulation resistance value and the ground capacitance value of the DC circuit are displayed by the display means, the measurement (calculation) result can be quickly and easily recognized visually.

請求項５に記載の発明は、請求項１から４のいずれかに記載の絶縁抵抗測定器または静電容量測定器において、警報を発信する警報発信手段を有し、演算された対地絶縁抵抗値または対地静電容量値が異常値である場合に警報を発信することを特徴としている。
（作用）
測定（演算）された対地絶縁抵抗値または対地静電容量値が異常値である場合、警報発信手段によって警報が発信されるため、即座に異常を認識し、詳細な調査、対策などを迅速かつ的確にとることができる。 Invention of Claim 5 has the alarm transmission means which transmits an alarm in the insulation resistance measuring device or electrostatic capacitance measuring device in any one of Claim 1 to 4, and calculated ground insulation resistance value Alternatively, a warning is transmitted when the ground capacitance value is an abnormal value.
(Function)
When the measured (calculated) ground insulation resistance value or ground capacitance value is an abnormal value, an alarm is transmitted by the alarm transmission means, so that the abnormality is immediately recognized, and detailed investigations and countermeasures can be quickly performed. It can be taken accurately.

請求項６に記載の発明は、直流回路の対地絶縁抵抗値を測定する絶縁抵抗測定方法であって、直流回路の正極側と大地間に地絡抵抗を接続して、この地絡抵抗の端末間電圧が安定する正極側安定電圧値を測定し、直流回路の負極側と大地間に地絡抵抗を接続して、この地絡抵抗の端末間電圧が安定する負極側安定電圧値を測定し、正極側安定電圧値と負極側安定電圧値とに基づいて、直流回路の対地絶縁抵抗値を演算することを特徴としている。
（作用）
地絡抵抗が接続された接続回路に基づいて、正極側安定電圧値、負極側安定電圧値および、地絡抵抗の抵抗値、直流回路の両極間電圧値から、正極側絶縁抵抗値と負極側絶縁抵抗値とを演算（測定）できる。しかも、直流回路の正／負極側と大地間に地絡抵抗を接続し、その端末間電圧を測定するだけであるため、直流回路を停電させることなく活線状態のままで測定できる。 The invention according to claim 6 is an insulation resistance measuring method for measuring a ground insulation resistance value of a DC circuit, wherein a ground fault resistance is connected between the positive electrode side of the DC circuit and the ground, and the terminal of the ground fault resistance is provided. Measure the positive side stable voltage value that stabilizes the voltage across the ground, connect a ground fault resistance between the negative side of the DC circuit and the ground, and measure the negative side stable voltage value that stabilizes the voltage across the terminal of this ground fault resistance. Based on the positive side stable voltage value and the negative side stable voltage value, the ground insulation resistance value of the DC circuit is calculated.
(Function)
Based on the connection circuit to which the ground fault resistance is connected, the positive side stable voltage value, the negative side stable voltage value, the resistance value of the ground fault resistance, and the voltage value between both electrodes of the DC circuit, the positive side insulation resistance value and the negative side The insulation resistance value can be calculated (measured). In addition, since a ground fault resistance is connected between the positive / negative electrode side of the DC circuit and the ground and the voltage between the terminals is only measured, the DC circuit can be measured in a live line state without causing a power failure.

請求項７に記載の発明は、請求項６に記載の絶縁抵抗測定方法において、地絡抵抗の端末間電圧が所定の電圧に達するまでの過渡時間を測定し、この過渡時間と演算された対地絶縁抵抗値とに基づいて、直流回路の対地静電容量値を演算することを特徴としている。
（作用）
例えば、所定の電圧を初期電圧の３６．８％に設定することで、過渡時間が時定数となり、時定数＝静電容量×抵抗の関係式に基づいて、対地静電容量値を演算できる。 According to a seventh aspect of the present invention, in the insulation resistance measuring method according to the sixth aspect, a transient time until the terminal voltage of the ground fault resistance reaches a predetermined voltage is measured, and the ground calculated as the transient time is measured. The ground capacitance value of the DC circuit is calculated based on the insulation resistance value.
(Function)
For example, by setting the predetermined voltage to 36.8% of the initial voltage, the transient time becomes a time constant, and the ground capacitance value can be calculated based on the relational expression of time constant = capacitance × resistance.

請求項８に記載の発明は、直流回路の対地静電容量値を測定する静電容量測定方法であって、直流回路の正極側と大地間または負極側と大地間に地絡抵抗を接続して、この地絡抵抗の端末間電圧が所定の電圧に達するまでの過渡時間を測定し、この過渡時間と地絡抵抗が接続された極性側の対地絶縁抵抗値とに基づいて、直流回路の対地静電容量値を演算することを特徴としている。
（作用）
対地絶縁抵抗値が既知である場合、請求項７に記載の発明と同様にして、過渡時間に基づいて対地静電容量値を演算できる。 The invention according to claim 8 is a capacitance measuring method for measuring a ground capacitance value of a DC circuit, wherein a ground fault resistance is connected between the positive electrode side and the ground or between the negative electrode side and the ground of the DC circuit. Then, the transient time until the voltage between the terminals of the ground fault resistance reaches a predetermined voltage is measured, and based on the transient time and the ground side insulation resistance value to which the ground fault resistance is connected, the DC circuit It is characterized by calculating a ground capacitance value.
(Function)
When the ground insulation resistance value is known, the ground capacitance value can be calculated based on the transient time in the same manner as the seventh aspect of the invention.

請求項９に記載の発明は、請求項１から８のいずれかに記載の絶縁抵抗測定器、静電容量測定器、絶縁抵抗測定方法または静電容量測定方法において、地絡抵抗の抵抗値が、地絡事故が発生しても直流回路に影響を与えない高い値に設定されていることを特徴としている。
（作用）
地絡抵抗の抵抗値が高い値に設定されているため、測定中に万一地絡事故が発生したとしても、電力機器などに影響（障害）を与えることがない。 The invention according to claim 9 is the insulation resistance measuring instrument, capacitance measuring instrument, insulation resistance measuring method or capacitance measuring method according to any one of claims 1 to 8, wherein the resistance value of the ground fault resistance is It is characterized by being set to a high value that does not affect the DC circuit even if a ground fault occurs.
(Function)
Since the resistance value of the ground fault resistance is set to a high value, even if a ground fault accident occurs during the measurement, it does not affect (failure) the power equipment.

請求項１０に記載の発明は、地絡抵抗の安定電圧値が測定される請求項１から９のいずれかに記載の絶縁抵抗測定器または絶縁抵抗測定方法において、安定電圧値が所定の電圧範囲内に収まるように、地絡抵抗の抵抗値が設定されていることを特徴としている。
（作用）
例えば、電圧を高い精度で安定して測定できる電圧範囲内に地絡抵抗の安定電圧値が収まるように、地絡抵抗の抵抗値を設定することで、直流回路の対地絶縁抵抗値および対地静電容量値が高い精度で安定して測定される。 The invention according to claim 10 is the insulation resistance measuring instrument or the insulation resistance measuring method according to any one of claims 1 to 9, wherein the stable voltage value of the ground fault resistance is measured. It is characterized in that the resistance value of the ground fault resistance is set so as to be within.
(Function)
For example, by setting the resistance value of the ground fault resistance so that the stable voltage value of the ground fault resistance is within the voltage range where the voltage can be measured stably with high accuracy, the ground insulation resistance value and the ground resistance of the DC circuit are set. The capacitance value is stably measured with high accuracy.

請求項１１に記載の発明は、過渡時間が測定される請求項２〜１０のいずれか１項に記載の絶縁抵抗測定器、静電容量測定器、絶縁抵抗測定方法または静電容量測定方法において、過渡時間が所定の時間範囲内に収まるように、地絡抵抗の抵抗値が設定されていることを特徴としている。
（作用）
例えば、時間を容易かつ安定して測定できる時間範囲内に過渡時間が収まるように、地絡抵抗の抵抗値を設定することで、直流回路の対地静電容量値が高い精度で安定して測定される。 The invention according to claim 11 is the insulation resistance measuring instrument, capacitance measuring instrument, insulation resistance measuring method or capacitance measuring method according to any one of claims 2 to 10, wherein the transient time is measured. The resistance value of the ground fault resistance is set so that the transition time is within a predetermined time range.
(Function)
For example, by setting the resistance value of the ground fault resistance so that the transient time is within the time range where the time can be measured easily and stably, the ground capacitance value of the DC circuit can be measured stably with high accuracy. Is done.

請求項１に記載の発明によれば、地絡抵抗が直流回路の正／負極側と大地間に接続され、地絡抵抗の安定電圧値に基づいて対地絶縁抵抗値が測定（演算）されるため、微小かつ不安定な漏洩電流に基づく測定に比べて、安定で高精度、かつ広範囲な（被測定抵抗値の範囲が広い）測定が可能となる。また、地絡抵抗を接続し、その端末間電圧を測定するだけでよいため、測定器の設計、構造が容易、簡単となり、かつ、測定範囲が広く汎用性の高い測定器にすることができる。 According to the first aspect of the present invention, the ground fault resistance is connected between the positive / negative side of the DC circuit and the ground, and the ground insulation resistance value is measured (calculated) based on the stable voltage value of the ground fault resistance. Therefore, compared with the measurement based on the minute and unstable leakage current, it is possible to perform a stable, high-accuracy and wide-range measurement (a wide range of resistance values to be measured). In addition, since it is only necessary to connect the ground fault resistance and measure the voltage between the terminals, the design and structure of the measuring instrument is easy and simple, and the measuring instrument has a wide measuring range and high versatility. .

しかも、計時手段を設けることで、過渡時間と対地絶縁抵抗値とに基づいて、対地静電容量値が測定（演算）される。そして、直流回路の対地絶縁抵抗値と対地静電容量値とが測定されることで、活線状態における直流回路の絶縁状態を的確に診断することが可能となり、この診断に基づいて、地絡事故による電力機器への障害などを未然かつ的確に防止することが可能となる。 Moreover, by providing the time measuring means, the ground capacitance value is measured (calculated) based on the transient time and the ground insulation resistance value. Then, by measuring the ground insulation resistance value and the ground capacitance value of the DC circuit, it becomes possible to accurately diagnose the insulation state of the DC circuit in the live line state. This makes it possible to prevent power equipment from being damaged due to an accident.

請求項６に記載の発明によれば、地絡抵抗を接続して、正極側安定電圧値と負極側安定電圧値とを測定するだけで、正極側絶縁抵抗値と負極側絶縁抵抗値とを測定（演算）できるため、容易かつ迅速な測定が可能となる。しかも、過渡時間を測定するだけで、対地静電容量値を測定（演算）できる。そして、対地絶縁抵抗値と対地静電容量値とを現地において容易かつ迅速に測定できることで、定期的に絶縁状態を診断することが実効的に可能となり、地絡事故の予防、対策を確立できる。 According to the sixth aspect of the present invention, the positive-side insulation resistance value and the negative-side insulation resistance value are obtained simply by connecting the ground fault resistance and measuring the positive-side stable voltage value and the negative-side stable voltage value. Since measurement (calculation) can be performed, easy and quick measurement is possible. Moreover, the ground capacitance value can be measured (calculated) simply by measuring the transient time. In addition, since the ground insulation resistance value and the ground capacitance value can be measured easily and quickly in the field, it is possible to effectively diagnose the insulation state on a regular basis and to establish prevention and countermeasures for ground faults. .

以下、本発明を図示の実施形態に基づいて説明する。 Hereinafter, the present invention will be described based on the illustrated embodiments.

図１は、本発明の実施形態に係る絶縁抵抗測定器１を直流回路Ｄに接続した状態を示す概略回路図である。この絶縁抵抗測定器１は、直流回路Ｄの正極側と大地間および負極側と大地間に切換スイッチ２（切換手段）を介して切換接続される地絡抵抗３と、この地絡抵抗３の端末間電圧などを測定する電圧測定部４（電圧測定手段）と、測定結果などを表示する表示部５（表示手段）と、警報音を発する警報部６（警報発信手段）と、これらの制御などを行う制御部７とを備えている。 FIG. 1 is a schematic circuit diagram showing a state in which an insulation resistance measuring instrument 1 according to an embodiment of the present invention is connected to a DC circuit D. The insulation resistance measuring instrument 1 includes a ground fault resistor 3 that is switched and connected between the positive electrode side and the ground of the DC circuit D and between the negative electrode side and the ground via a changeover switch 2 (switching means). A voltage measuring unit 4 (voltage measuring unit) for measuring the voltage between terminals, a display unit 5 (display unit) for displaying a measurement result, an alarm unit 6 (alarm transmitting unit) for generating an alarm sound, and control thereof The control part 7 which performs etc. is provided.

切換スイッチ２は、スイッチ２ａ，２ｂ，２ｃを有し、スイッチ２ａに正極側導線８が接続され、スイッチ２ｃに負極側導線９が接続されている。また、スイッチ２ａ，２ｂ間および、スイッチ２ｂ，２ｃ間には、バランス抵抗１０が設けられ、本実施形態では、このバランス抵抗１０の抵抗値は、５０Ω程度に設定されている。 The changeover switch 2 includes switches 2a, 2b, and 2c. A positive-side conductor 8 is connected to the switch 2a, and a negative-side conductor 9 is connected to the switch 2c. A balance resistor 10 is provided between the switches 2a and 2b and between the switches 2b and 2c. In this embodiment, the resistance value of the balance resistor 10 is set to about 50Ω.

地絡抵抗３は、一端部が各スイッチ２ａ，２ｂ，２ｃに接続され、他端部には接地導線１１が接続されている。そして、スイッチ２ａ，２ｂ，２ｃは、いずれも常時はオフ（開）状態であり、スイッチ２ａがオン（閉）されると、正極側導線８、スイッチ２ａ、地絡抵抗３および接地導線１１がつながり、スイッチ２ｃがオンされると、負極側導線９、スイッチ２ｃ、地絡抵抗３および接地導線１１がつながるようになっている。また、本実施形態では、地絡抵抗３の抵抗値は５００ｋΩに設定されているが、その設定基準については後述する。 One end of the ground fault resistor 3 is connected to each of the switches 2a, 2b, 2c, and the ground conductor 11 is connected to the other end. The switches 2a, 2b, and 2c are normally off (open), and when the switch 2a is turned on (closed), the positive conductor 8, the switch 2a, the ground fault resistor 3, and the ground conductor 11 are connected. When the switch 2c is turned on, the negative electrode side conductor 9, the switch 2c, the ground fault resistor 3, and the ground conductor 11 are connected. In the present embodiment, the resistance value of the ground fault resistor 3 is set to 500 kΩ, and the setting criteria will be described later.

電圧測定部４は、地絡抵抗３の両端末と正極側導線８および負極側導線９に接続され、地絡抵抗３の端末間電圧および正負極間電圧などを測定する高抵抗電圧計である。また、Ａ／Ｄ変換手段を備え、測定した電圧値をデジタル変換し、ＲＡＭ（デュアルポートＲＡＭなど）に書き込むようになっている。 The voltage measuring unit 4 is a high resistance voltmeter that is connected to both terminals of the ground fault resistor 3 and the positive electrode side conductor 8 and the negative electrode side conductor 9 and measures the terminal voltage and the positive and negative electrode voltage of the ground fault resistor 3. . In addition, an A / D conversion means is provided to digitally convert the measured voltage value and write it into a RAM (such as a dual port RAM).

表示部５は、制御部７からの出力命令によって測定（演算）結果や測定状態などを表示し、警報部６はスピーカーを備え、制御部７からの出力命令によって警報音を発するものである。 The display unit 5 displays a measurement (calculation) result, a measurement state, and the like according to an output command from the control unit 7, and the alarm unit 6 includes a speaker and emits an alarm sound according to an output command from the control unit 7.

制御部７は、切換スイッチ２の開閉、電圧測定部４の動作、表示部５および警報部６の出力などを制御するとともに、時間を計測する計時部（計時手段）と、直流回路Ｄの対地絶縁抵抗値や対地静電容量値を演算する演算部とを備えている。そして、電圧測定部４のＲＡＭに書き込まれた電圧値を監視しながら、計時部によって地絡抵抗３の端末間電圧が所定の電圧に達するまでの過渡時間を測定する。また、演算部によって、電圧測定部４で測定された地絡抵抗３の安定電圧値に基づいて直流回路Ｄの対地絶縁抵抗値を演算し、この対地絶縁抵抗値と計時部で測定された過渡時間とに基づいて、直流回路Ｄの対地静電容量値を演算するものである。そしてこの演算結果は、出力命令とともに表示部５に送信されるとともに、演算結果が異常値である場合には、警報音出力命令が警報部に送信される。なお、具体的な演算方法などについては後述する。 The control unit 7 controls the opening / closing of the changeover switch 2, the operation of the voltage measuring unit 4, the outputs of the display unit 5 and the alarm unit 6, and the time measuring unit (time measuring means) for measuring time and the ground of the DC circuit D A calculation unit that calculates an insulation resistance value and a ground capacitance value. And while monitoring the voltage value written in RAM of the voltage measurement part 4, the time until the voltage between terminals of the ground fault resistance 3 reaches a predetermined voltage is measured by the time measuring part. Further, the calculation unit calculates a ground insulation resistance value of the DC circuit D based on the stable voltage value of the ground fault resistance 3 measured by the voltage measurement unit 4, and the ground insulation resistance value and the transient measured by the time measuring unit. The ground capacitance value of the DC circuit D is calculated based on the time. The calculation result is transmitted to the display unit 5 together with the output command. When the calculation result is an abnormal value, an alarm sound output command is transmitted to the alarm unit. A specific calculation method will be described later.

次に、このような構成の絶縁抵抗測定器１の測定動作について説明する。 Next, the measurement operation of the insulation resistance measuring instrument 1 having such a configuration will be described.

本実施形態では、測定対象である直流電源系統の直流回路Ｄの電源電圧Ｖは、１１０Ｖであり、正極母線Ｄ１と負極母線Ｄ２との間に直流制御回路地絡継電器（以下「６４Ｄ」という）が接続されている。また、図１中、Ｒｐは直流回路Ｄの正極側絶縁抵抗（値）、Ｒｎは負極側絶縁抵抗（値）、Ｃｐは正極側静電容量（値）、Ｃｎは負極側静電容量（値）を示している。 In this embodiment, the power supply voltage V of the DC circuit D of the DC power supply system to be measured is 110 V, and a DC control circuit ground fault relay (hereinafter referred to as “64D”) is provided between the positive bus D1 and the negative bus D2. Is connected. In FIG. 1, Rp is the positive-side insulation resistance (value) of the DC circuit D, Rn is the negative-side insulation resistance (value), Cp is the positive-side capacitance (value), and Cn is the negative-side capacitance (value). ).

まず、絶縁抵抗測定器１を直流回路Ｄに接続する。すなわち、正極側導線８を正極母線Ｄ１に接続し、負極側導線９を負極母線Ｄ２に接続するとともに、接地導線１１を接地母線Ｄ３に接続する。このとき、切換スイッチ２はすべてオフ状態となっている。次に、６４Ｄを「切」状態とし、絶縁抵抗測定器１を起動させる。これにより、図２に示すフローチャートに従って、自動測定が行われる。 First, the insulation resistance measuring instrument 1 is connected to the DC circuit D. That is, the positive electrode side conductor 8 is connected to the positive electrode bus D1, the negative electrode side conductor 9 is connected to the negative electrode bus D2, and the ground conductor 11 is connected to the ground bus D3. At this time, all the changeover switches 2 are in the OFF state. Next, 64D is set to the “OFF” state, and the insulation resistance measuring instrument 1 is activated. Thereby, automatic measurement is performed according to the flowchart shown in FIG.

まず、スイッチ２ｂがオンされ、短時間後にスイッチ２ｂがオフされるとともに、スイッチ２ａがオンされる（ステップＳ１）。これにより、図３（ａ）に示すように、地絡抵抗３が直流回路Ｄの正極側に接地され、地絡抵抗３と正極側絶縁抵抗Ｒｐとが並列状態となる。次に、地絡抵抗３の端末間電圧が所定の電圧に達するまでの過渡時間が測定される（ステップＳ２）。ここで、本実施形態では所定の電圧を、初期電圧（地絡直前の電圧）の３６．８％、すなわち、電源電圧Ｖ×１／２×０．３６８＝２０．２４Ｖとし、これにより、過渡時間は時定数τｐとなる。続いて、地絡抵抗３の端末間電圧が安定する正極側安定電圧値Ｖｐが測定され（ステップＳ３）、これら時定数τｐと正極側安定電圧値Ｖｐとが制御部７のＲＡＭに記憶される。その後、スイッチ２ａがオフされ、スイッチ２ｂがオンされることで復旧し（ステップＳ４）、負極側に対して同様な測定が行われる。すなわち、短時間後にスイッチ２ｂがオフされるとともに、スイッチ２ｃがオンされる（ステップＳ５）。これにより、図３（ｂ）に示すように、地絡抵抗３が直流回路Ｄの負極側に接地され、地絡抵抗３と負極側絶縁抵抗Ｒｎとが並列状態となる。続いて、正極側の場合と同様にして、過渡時間（時定数τｎ）と負極側安定電圧値Ｖｎとが測定され（ステップＳ６，Ｓ７）、その測定値が制御部７のＲＡＭに記憶される。そして、スイッチ２ｃがオフされ（ステップＳ８）、次のようにして、直流回路Ｄの正極側絶縁抵抗値Ｒｐ、負極側絶縁抵抗値Ｒｎおよび、静電容量値Ｃ（正極側静電容量値Ｃｐと負極側静電容量値Ｃｎとを合わせた等価静電容量値）が演算される（ステップＳ９）。 First, the switch 2b is turned on, and after a short time, the switch 2b is turned off and the switch 2a is turned on (step S1). Thereby, as shown to Fig.3 (a), the ground fault resistance 3 is earth | grounded by the positive electrode side of the DC circuit D, and the ground fault resistance 3 and the positive electrode side insulation resistance Rp will be in a parallel state. Next, the transition time until the terminal voltage of the ground fault resistor 3 reaches a predetermined voltage is measured (step S2). Here, in this embodiment, the predetermined voltage is set to 36.8% of the initial voltage (the voltage just before the ground fault), that is, the power supply voltage V × 1/2 × 0.368 = 20.24V, and thus the transient voltage Time is a time constant τp. Subsequently, the positive side stable voltage value Vp at which the terminal voltage of the ground fault resistor 3 is stabilized is measured (step S3), and the time constant τp and the positive side stable voltage value Vp are stored in the RAM of the control unit 7. . Thereafter, the switch 2a is turned off and the switch 2b is turned on to recover (step S4), and the same measurement is performed on the negative electrode side. That is, the switch 2b is turned off after a short time, and the switch 2c is turned on (step S5). Thereby, as shown in FIG.3 (b), the ground fault resistance 3 is earth | grounded by the negative electrode side of the DC circuit D, and the ground fault resistance 3 and the negative electrode side insulation resistance Rn will be in a parallel state. Subsequently, as in the case of the positive electrode side, the transient time (time constant τn) and the negative electrode side stable voltage value Vn are measured (steps S6 and S7), and the measured values are stored in the RAM of the control unit 7. . Then, the switch 2c is turned off (step S8), and the positive side insulation resistance value Rp, the negative side insulation resistance value Rn, and the capacitance value C (positive side capacitance value Cp) of the DC circuit D are as follows. And an equivalent capacitance value obtained by combining the negative electrode side capacitance value Cn) (step S9).

すなわち、図３（ａ）、（ｂ）の回路図から、次の関係式が成り立つ。ここで、Ｒ３は地絡抵抗３の抵抗値とする。 That is, the following relational expression is established from the circuit diagrams of FIGS. Here, R3 is the resistance value of the ground fault resistance 3.

Ｖｐ：（Ｖ−Ｖｐ）＝Ｒｐ×Ｒ３／（Ｒｐ＋Ｒ３）：Ｒｎ
Ｖｎ：（Ｖ−Ｖｎ）＝Ｒｎ×Ｒ３／（Ｒｎ＋Ｒ３）：Ｒｐ
この関係式から、次の演算式が得られる。 Vp: (V−Vp) = Rp × R3 / (Rp + R3): Rn
Vn: (V−Vn) = Rn × R3 / (Rn + R3): Rp
From this relational expression, the following arithmetic expression is obtained.

Ｒｐ＝（Ｖ−Ｖｎ−Ｖｐ）×Ｒ３／Ｖｎ
Ｒｎ＝（Ｖ−Ｖｎ−Ｖｐ）×Ｒ３／Ｖｐ
そして、この演算式に測定された安定電圧値Ｖｐ，Ｖｎなどを代入することで、直流回路Ｄの正極側絶縁抵抗値Ｒｐと負極側絶縁抵抗値Ｒｎとが演算されるものである。 Rp = (V−Vn−Vp) × R3 / Vn
Rn = (V−Vn−Vp) × R3 / Vp
Then, the positive voltage side insulation resistance value Rp and the negative voltage side insulation resistance value Rn of the DC circuit D are calculated by substituting the measured stable voltage values Vp, Vn and the like into this calculation formula.

また、直流回路Ｄの静電容量Ｃと地絡抵抗３および、正極側絶縁抵抗Ｒｐまたは負極側絶縁抵抗Ｒｎとは、図４（ａ）に示す回路図状態となり、この回路図と時定数＝静電容量×抵抗の関係式（図４（ｂ）参照）とから、次の演算式が得られる。 Further, the electrostatic capacitance C of the DC circuit D, the ground fault resistance 3, and the positive-side insulation resistance Rp or the negative-side insulation resistance Rn are in the circuit diagram state shown in FIG. 4A, and this circuit diagram and time constant = From the relational expression of capacitance × resistance (see FIG. 4B), the following arithmetic expression is obtained.

Ｃ＝τｐ×（１／Ｒｐ＋１／Ｒ３）＝τｎ×（１／Ｒｎ＋１／Ｒ３）
そして、この演算式に測定された時定数τｐまたはτｎと、正極側絶縁抵抗値Ｒｐまたは負極側絶縁抵抗値Ｒｎを代入することで、直流回路Ｄの静電容量値Ｃが演算されるものである。 C = τp × (1 / Rp + 1 / R3) = τn × (1 / Rn + 1 / R3)
The capacitance value C of the DC circuit D is calculated by substituting the measured time constant τp or τn and the positive-side insulation resistance value Rp or the negative-side insulation resistance value Rn. is there.

例えば、正極側安定電圧値Ｖｐが１．０６３Ｖ、負極側安定電圧値Ｖｎが２．６５７Ｖで、時定数τｐおよびτｎが１．０秒だとし、これらの値と電源電圧Ｖ＝１１０Ｖ、Ｒ３＝５００ｋΩとを上記の演算式に代入すると、以下の演算結果が得られる。 For example, assuming that the positive side stable voltage value Vp is 1.063 V, the negative side stable voltage value Vn is 2.657 V, and the time constants τp and τn are 1.0 seconds, these values and the power supply voltage V = 110 V, R3 = Substituting 500 kΩ into the above equation, the following calculation result is obtained.

正極側絶縁抵抗値Ｒｐ＝２０．０ＭΩ
負極側絶縁抵抗値Ｒｎ＝５０．０ＭΩ
静電容量値Ｃ＝２μＦ
そして、これらの演算（測定）結果が表示部５に表示される（ステップＳ１０）とともに、演算された絶縁抵抗値Ｒｐ，Ｒｎまたは静電容量値Ｃが異常値であるか否かが判断され(ステップＳ１１)、異常値である場合には、警報部６から警報音が発せられる（ステップＳ１２）。ここで、異常値であるか否かの判断は、本実施形態では、絶縁抵抗値Ｒｐ，Ｒｎが１ＭΩ以下、または、静電容量値Ｃが２００μＦを越す場合を異常値としている。なお、この異常値の判断基準は、電力機器などの重要性や運用状況などによって決められ、また、異常値の判断基準を変更可能にしてもよい。 Positive side insulation resistance Rp = 20.0MΩ
Negative side insulation resistance Rn = 50.0MΩ
Capacitance value C = 2μF
Then, these calculation (measurement) results are displayed on the display unit 5 (step S10), and it is determined whether or not the calculated insulation resistance values Rp and Rn or the capacitance value C are abnormal values ( In step S11), if it is an abnormal value, an alarm sound is emitted from the alarm unit 6 (step S12). Here, in this embodiment, the determination as to whether or not the value is an abnormal value is an abnormal value when the insulation resistance values Rp and Rn are 1 MΩ or less or the capacitance value C exceeds 200 μF. It should be noted that the criterion for judging the abnormal value is determined by the importance of the electric power device or the like or the operation status, and the criterion for judging the abnormal value may be changeable.

以上のように、本絶縁抵抗測定器１によれば、地絡抵抗３が直流回路Ｄの正／負極側に接地され、地絡抵抗３の安定電圧値Ｖｐ，Ｖｎに基づいて絶縁抵抗値Ｒｐ，Ｒｎが測定（演算）されるため、微小かつ不安定な漏洩電流に基づく測定に比べて、安定で高精度、かつ広範囲な（被測定抵抗値の範囲が広い）測定が可能となる。また、直流回路Ｄの正／負極側に地絡抵抗３が接地され、その端末間電圧が測定されるだけであるため、直流回路Ｄを停電させることなく活線状態のままで測定できる。さらに、地絡抵抗３を接地し、その端末間電圧を測定するだけでよいため、本絶縁抵抗測定器１の設計、構造が容易、簡単となり、かつ、測定範囲が広く汎用性の高い測定器にすることが可能となる。 As described above, according to the insulation resistance measuring instrument 1, the ground fault resistance 3 is grounded to the positive / negative side of the DC circuit D, and the insulation resistance value Rp is based on the stable voltage values Vp and Vn of the ground fault resistance 3. , Rn are measured (calculated), and stable, highly accurate, and wide-ranging (a wide range of resistance values to be measured) can be obtained as compared with measurement based on minute and unstable leakage current. Further, since the ground fault resistor 3 is grounded on the positive / negative side of the DC circuit D and the voltage between the terminals is only measured, the DC circuit D can be measured in a live state without causing a power failure. Furthermore, since it is only necessary to ground the grounding resistance 3 and measure the voltage between the terminals, the design and structure of the insulation resistance measuring instrument 1 is easy and simple, and the measuring range is wide and versatile. It becomes possible to.

一方、過渡時間（時定数τｐ，τｎ）が測定されることで、この過渡時間と絶縁抵抗値Ｒｐ，Ｒｎとに基づいて、静電容量値Ｃが自動測定（演算）される。このようにして、直流回路Ｄの絶縁抵抗値Ｒｐ，Ｒｎと静電容量値Ｃとが測定されることで、活線状態における直流回路Ｄの絶縁状態を的確に診断することが可能となり、この診断に基づいて、地絡事故による電力機器への障害などを未然かつ的確に防止することが可能となる。例えば、従来、静電容量値Ｃが未知数であったために、遮断器トリップ回路の接地時に誤遮断（ミストリップ）を生じるおそれがあったが、本絶縁抵抗測定器１によって静電容量値Ｃを正確に把握できることで、このような誤遮断を防止することが可能となる。 On the other hand, by measuring the transient time (time constant τp, τn), the capacitance value C is automatically measured (calculated) based on the transient time and the insulation resistance values Rp, Rn. In this way, by measuring the insulation resistance values Rp, Rn and the capacitance value C of the DC circuit D, it becomes possible to accurately diagnose the insulation state of the DC circuit D in the live line state. Based on the diagnosis, it is possible to prevent the power equipment from being damaged due to a ground fault accident. For example, since the capacitance value C has been unknown in the past, there is a risk of erroneous interruption (mistrip) when the circuit breaker trip circuit is grounded. It is possible to prevent such erroneous shut-off by being accurately grasped.

また、表示部５によって測定結果である絶縁抵抗値Ｒｐ，Ｒｎと静電容量値Ｃとが表示されるため、目視によって測定結果を迅速かつ容易に認識できる。さらに、測定された絶縁抵抗値Ｒｐ，Ｒｎまたは静電容量値Ｃが異常である場合、警報部６によって警報音が発せられるため、即座に異常を認識し、詳細な調査、対策などを迅速かつ的確にとることができる。 Moreover, since the insulation resistance values Rp and Rn and the capacitance value C, which are measurement results, are displayed on the display unit 5, the measurement results can be quickly and easily recognized visually. Further, when the measured insulation resistance value Rp, Rn or capacitance value C is abnormal, an alarm sound is emitted by the alarm unit 6, so that the abnormality is immediately recognized, and detailed investigation, countermeasures, etc. can be quickly performed. It can be taken accurately.

ところで、地絡抵抗３の抵抗値Ｒ３は、次のようにして設定（選定）される。なお、この設定方法は、後述する絶縁抵抗測定方法および静電容量測定方法の場合も同様である。 By the way, the resistance value R3 of the ground fault resistance 3 is set (selected) as follows. This setting method is the same in the case of an insulation resistance measuring method and a capacitance measuring method described later.

第１に、測定中に万一地絡事故が発生したとしても、直流電源系統（直流回路）に影響を与えない高い値に抵抗値Ｒ３を設定する。例えば、直流制御回路地絡継電器（６４Ｄ）の整定値が１０ｋΩであるとすると、この１０ｋΩ以上に設定する。これにより、万一地絡事故が発生したとしても、電力機器などに影響（障害）を与えることを防止できる。また、抵抗値Ｒ３を１０ｋΩとした場合、被測定極性以外の極が直流地絡を起こしたとしても、地絡抵抗３に流れる電流は１１ｍＡ程度であり、これによる発熱量も１．２Ｗ程度であるため、短時間であれば熱的にも問題がないと考えられる。 First, even if a ground fault occurs during measurement, the resistance value R3 is set to a high value that does not affect the DC power supply system (DC circuit). For example, if the set value of the DC control circuit ground fault relay (64D) is 10 kΩ, it is set to 10 kΩ or more. As a result, even if a ground fault occurs, it is possible to prevent the power device and the like from being affected (failure). In addition, when the resistance value R3 is 10 kΩ, even if a pole other than the polarity to be measured causes a DC ground fault, the current flowing through the ground fault resistor 3 is about 11 mA, and the amount of heat generated by this is about 1.2 W. Therefore, it can be considered that there is no problem with heat for a short time.

第２に、安定電圧値Ｖｐ，Ｖｎが所定の電圧範囲内に収まるように、抵抗値Ｒ３を設定する。すなわち、電圧測定部４による測定誤差や、人が電圧値を読み取る場合の読み取り誤差を考慮すると、安定電圧値Ｖｐ，Ｖｎが１Ｖ程度以上で１０Ｖ程度以下であることが好ましい。図５は、被測定回路の絶縁抵抗値Ｒｐ，Ｒｎと地絡抵抗３の抵抗値Ｒ３との組み合わせにおける安定電圧値Ｖｐ，Ｖｎを示したものであり、カッコ内のパーセンテージは、絶縁抵抗値Ｒｐ，Ｒｎに対する抵抗値Ｒ３の大きさ（割合）を表したものである。この図から、安定電圧値Ｖｐ，Ｖｎが１Ｖ程度以上で１０Ｖ程度以下に収まるようにするには、抵抗値Ｒ３を絶縁抵抗値Ｒｐ，Ｒｎの１〜１０％程度に設定する必要があると言える。そして、このような値に抵抗値Ｒ３を設定することで、安定電圧値Ｖｐ，Ｖｎが高い精度で安定して測定され、直流回路Ｄの絶縁抵抗値Ｒｐ，Ｒｎおよび静電容量値Ｃが高い精度で安定して測定できる。 Second, the resistance value R3 is set so that the stable voltage values Vp and Vn are within a predetermined voltage range. That is, in consideration of measurement errors caused by the voltage measuring unit 4 and reading errors when a person reads voltage values, the stable voltage values Vp and Vn are preferably about 1 V or more and about 10 V or less. FIG. 5 shows the stable voltage values Vp, Vn in the combination of the insulation resistance values Rp, Rn of the circuit under test and the resistance value R3 of the ground fault resistance 3, and the percentage in parentheses indicates the insulation resistance value Rp. , Rn represents the magnitude (ratio) of the resistance value R3. From this figure, it can be said that the resistance value R3 needs to be set to about 1 to 10% of the insulation resistance values Rp and Rn so that the stable voltage values Vp and Vn fall within the range of about 1V to about 10V. . By setting the resistance value R3 to such a value, the stable voltage values Vp and Vn are stably measured with high accuracy, and the insulation resistance values Rp and Rn and the capacitance value C of the DC circuit D are high. Accurate and stable measurement.

第３に、過渡時間である時定数τｐ，τｎが所定の時間範囲内に収まるように、抵抗値Ｒ３を設定する。すなわち、計時部による測定誤差や、地絡抵抗３への地絡継続時間を考慮すると、過渡時間が５〜６０秒程度が好ましい。図６は、被測定回路の静電容量値Ｃと地絡抵抗３の抵抗値Ｒ３との組み合わせにおける過渡時間を示したものである。この図から、過渡時間が５〜６０秒程度に収まるようにするには、静電容量値Ｃが５００μＦ以下の場合、抵抗値Ｒ３を０．１〜０．５ＭΩ程度に設定する必要があると言える。そして、このような値に抵抗値Ｒ３を設定することで、過渡時間が高い精度で、容易にかつ安定して測定され、直流回路Ｄの静電容量値Ｃが高い精度で安定して測定できる。 Third, the resistance value R3 is set so that the time constants τp and τn, which are transient times, fall within a predetermined time range. That is, considering the measurement error due to the time measuring unit and the ground fault continuation time to the ground fault resistance 3, the transient time is preferably about 5 to 60 seconds. FIG. 6 shows the transient time in the combination of the capacitance value C of the circuit to be measured and the resistance value R3 of the ground fault resistance 3. From this figure, it is necessary to set the resistance value R3 to about 0.1 to 0.5 MΩ when the capacitance value C is 500 μF or less in order to keep the transient time within about 5 to 60 seconds. I can say that. By setting the resistance value R3 to such a value, the transient time can be easily and stably measured with high accuracy, and the capacitance value C of the DC circuit D can be stably measured with high accuracy. .

ここで、第２の設定基準と第３の設定基準とは、相反する面がある。すなわち、安定電圧値Ｖｐ，Ｖｎ、ひいては絶縁抵抗値Ｒｐ，Ｒｎの測定精度の面からは、地絡抵抗３の抵抗値Ｒ３が大きい方が、安定電圧値Ｖｐ，Ｖｎが大きいために測定誤差が小さい。しかしながら、静電容量値Ｃの測定精度の面からは、安定電圧値Ｖｐ，Ｖｎが大きいと、過渡時間（時定数τｐ，τｎ）の誤差（バラツキ）が大きくなるために、静電容量値Ｃの測定精度が低くなるというものである。このため、絶縁抵抗値Ｒｐ，Ｒｎと静電容量値Ｃとの必要測定誤差を考慮して、地絡抵抗３の抵抗値Ｒ３を設定する必要がある。 Here, the second setting criterion and the third setting criterion are contradictory. That is, from the viewpoint of measurement accuracy of the stable voltage values Vp and Vn, and hence the insulation resistance values Rp and Rn, the measurement voltage error is larger when the resistance value R3 of the ground fault resistor 3 is larger and the stable voltage values Vp and Vn are larger. small. However, from the viewpoint of the measurement accuracy of the capacitance value C, if the stable voltage values Vp and Vn are large, the error (variation) of the transient time (time constants τp and τn) becomes large. The measurement accuracy is reduced. For this reason, it is necessary to set the resistance value R3 of the ground fault resistor 3 in consideration of the necessary measurement error between the insulation resistance values Rp, Rn and the capacitance value C.

以上のようにして、地絡抵抗３の抵抗値Ｒ３が設定されるが、実務上は、例えば次のようにして設定される。 As described above, the resistance value R3 of the ground fault resistor 3 is set. However, in practice, for example, it is set as follows.

まず、絶縁抵抗測定器１の内部抵抗値を含めて、地絡抵抗３の抵抗値Ｒ３を５００ｋΩとして測定する。そして、過渡時間（時定数τｐ，τｎ）が６０秒以内であれば、そのまま測定を続行し、安定電圧値Ｖｐ，Ｖｎを測定する。一方、６０秒を過ぎても地絡抵抗３の端末間電圧が上記の所定電圧に達しない場合（過渡時間が６０秒を超す場合）には、地絡抵抗３の抵抗値Ｒ３を１００ｋΩとして、測定をし直す。あるいは、安定電圧値Ｖｐ，Ｖｎが１０Ｖ以上であり、静電容量値Ｃの測定精度を高める必要がある場合には、地絡抵抗３の抵抗値Ｒ３を１００ｋΩとして、測定をし直す、というものである。なお、直流回路Ｄの正極側および負極側には、同じ抵抗値Ｒ３の地絡抵抗３を接地する必要がある。 First, including the internal resistance value of the insulation resistance measuring instrument 1, the resistance value R3 of the ground fault resistance 3 is measured as 500 kΩ. If the transient time (time constant τp, τn) is within 60 seconds, the measurement is continued as it is, and the stable voltage values Vp, Vn are measured. On the other hand, when the voltage between the terminals of the ground fault resistor 3 does not reach the predetermined voltage even after 60 seconds (when the transient time exceeds 60 seconds), the resistance value R3 of the ground fault resistor 3 is set to 100 kΩ, Repeat the measurement. Alternatively, when the stable voltage values Vp and Vn are 10 V or more and it is necessary to increase the measurement accuracy of the capacitance value C, the resistance value R3 of the ground fault resistor 3 is set to 100 kΩ and the measurement is performed again. It is. It is necessary to ground the ground fault resistor 3 having the same resistance value R3 on the positive electrode side and the negative electrode side of the DC circuit D.

ところで、本実施形態では、絶縁抵抗値Ｒｐ，Ｒｎと静電容量値Ｃとを同時に測定できるようにしているが、どちらか一方のみを測定する測定器にすることもできる。すなわち、地絡抵抗３の安定電圧値Ｖｐ，Ｖｎのみを測定し、絶縁抵抗値Ｒｐ，Ｒｎのみを演算する絶縁抵抗測定器であってもよい。また、絶縁抵抗値ＲｐまたはＲｎの少なくともどちらか一方が既知である場合に、その既知の極性側の過渡時間（時定数τｐまたはτｎ）のみを測定し、静電容量値Ｃのみを演算する静電容量測定器であってもよい。なお、このような静電容量測定器の場合、既知の絶縁抵抗値ＲｐまたはＲｎを測定器に入力して、静電容量値Ｃを測定することになる。そして、このような絶縁抵抗測定器または静電容量測定器にすることで、測定器の構成のさらなる簡素化、測定時間の短縮化などを図ることができる。 By the way, in the present embodiment, the insulation resistance values Rp, Rn and the capacitance value C can be measured at the same time, but a measuring instrument that measures only one of them can also be used. That is, an insulation resistance measuring instrument that measures only the stable voltage values Vp and Vn of the ground fault resistor 3 and calculates only the insulation resistance values Rp and Rn may be used. Further, when at least one of the insulation resistance values Rp or Rn is known, only the transient time (time constant τp or τn) on the known polarity side is measured, and only the capacitance value C is calculated. It may be a capacitance measuring device. In the case of such a capacitance measuring device, a known insulation resistance value Rp or Rn is input to the measuring device, and the capacitance value C is measured. Further, by using such an insulation resistance measuring device or a capacitance measuring device, it is possible to further simplify the configuration of the measuring device and shorten the measurement time.

また、本実施形態では、初期電圧（電源電圧Ｖの１／２）の３６．８％の電圧を所定電圧とし、この電圧に達した時点（時定数τｐまたはτｎ）を過渡時間としているが、所定電圧をこの電圧値に限らなくても、静電容量値Ｃを演算することができる。すなわち、図４（ｂ）に示すような電圧の時間的変化曲線に基づいて、他の電圧値とその過渡時間とから時定数を算出して、静電容量値Ｃを演算することができる。さらに、地絡による過渡現象が安定しても、上記のように安定電圧値ＶｐまたはＶｎが残るため、静電容量値Ｃを厳密に演算するには、初期電圧（電源電圧Ｖの１／２）から安定電圧値ＶｐまたはＶｎを差し引いた値の３６．８％を所定電圧として演算する必要がある。しかしながら、上記のように安定電圧値Ｖｐ，Ｖｎが５Ｖ程度以下であれば、これらの値を差し引かなくても、演算誤差は小さい。 In this embodiment, 36.8% of the initial voltage (1/2 of the power supply voltage V) is set as the predetermined voltage, and the time (time constant τp or τn) at which this voltage is reached is set as the transient time. Even if the predetermined voltage is not limited to this voltage value, the capacitance value C can be calculated. That is, the capacitance value C can be calculated by calculating a time constant from another voltage value and its transient time based on a voltage temporal change curve as shown in FIG. Further, even if the transient due to the ground fault is stabilized, the stable voltage value Vp or Vn remains as described above. Therefore, in order to calculate the capacitance value C strictly, the initial voltage (1/2 of the power supply voltage V) is used. 36.8% of the value obtained by subtracting the stable voltage value Vp or Vn from the above) must be calculated as the predetermined voltage. However, if the stable voltage values Vp and Vn are about 5 V or less as described above, the calculation error is small without subtracting these values.

ところで、本絶縁抵抗測定器１と同様な測定手順によって、人手による測定（絶縁抵抗測定方法および静電容量測定方法）もできる。すなわち、地絡抵抗とテスター（電圧測定手段）と時計（計時手段）とを用意し、上述した図２に示すフローチャートに従って、安定電圧値Ｖｐ，Ｖｎおよび過渡時間を測定することで、絶縁抵抗値Ｒｐ，Ｒｎと静電容量値Ｃとをその場で計算（演算）することができる。このように、特殊な計器などを用意しなくても、地絡抵抗やテスターなどを用意することで容易に測定することができるため、どの現場（現地）や直流電源系統においても、容易、迅速な測定が可能で、かつ、緊急時にも対応が可能となる。この結果、定期的な設備診断パトロールなどにおいて、直流回路Ｄの絶縁状態を的確に診断することが実効的に可能となり、地絡事故の予防、対策を確立できる。 Incidentally, manual measurement (insulation resistance measurement method and capacitance measurement method) can be performed by the same measurement procedure as that of the present insulation resistance measuring instrument 1. That is, by preparing a ground fault resistance, a tester (voltage measuring means) and a clock (time measuring means), and measuring the stable voltage values Vp and Vn and the transient time according to the flowchart shown in FIG. 2, the insulation resistance value is obtained. Rp, Rn and capacitance value C can be calculated (calculated) on the spot. In this way, it is possible to measure easily by preparing a ground fault resistance or a tester without preparing a special instrument, etc., so it can be easily and quickly performed at any site (site) or DC power supply system. Measurement is possible, and it is possible to respond in an emergency. As a result, it is possible to effectively diagnose the insulation state of the DC circuit D in a regular facility diagnosis patrol and the like, and prevention of ground faults and countermeasures can be established.

本発明の実施形態に係る絶縁抵抗測定器を直流回路に接続した状態を示す概略回路図。The schematic circuit diagram which shows the state which connected the insulation resistance measuring device which concerns on embodiment of this invention to the DC circuit. 本発明の実施形態に係る絶縁抵抗測定器の測定フローを示すフローチャート。The flowchart which shows the measurement flow of the insulation resistance measuring device which concerns on embodiment of this invention. 本発明の実施形態に係る絶縁抵抗測定器によって、地絡抵抗が直流回路の正極側に接地された状態を示す一部回路図（ａ）と、負極側に接地された状態を示す一部回路図（ｂ）。The partial circuit diagram (a) which shows the state by which the ground fault resistance was earth | grounded by the positive electrode side of a DC circuit with the insulation resistance measuring device which concerns on embodiment of this invention, and the partial circuit which shows the state earth | grounded by the negative electrode side FIG. 本発明の実施形態に係る絶縁抵抗測定器によって、地絡抵抗が直流回路に接地された状態における静電容量との関係を示す概略回路図（ａ）と、電圧の時間的変化を示す図（ｂ）。The schematic circuit diagram (a) which shows the relationship with the electrostatic capacitance in the state by which the ground fault resistance was earth | grounded by the DC circuit by the insulation resistance measuring device which concerns on embodiment of this invention, and the figure which shows the time change of a voltage ( b). 本発明の実施形態において、被測定回路の絶縁抵抗値と地絡抵抗の抵抗値との組み合わせにおける安定電圧値を示す図。The figure which shows the stable voltage value in the combination of the insulation resistance value of a to-be-measured circuit, and the resistance value of a ground fault resistance in embodiment of this invention. 本発明の実施形態において、被測定回路の静電容量値と地絡抵抗の抵抗値との組み合わせにおける過渡時間を示す図。The figure which shows the transient time in the combination of the electrostatic capacitance value of a to-be-measured circuit, and the resistance value of a ground fault resistance in embodiment of this invention.

Explanation of symbols

１絶縁抵抗測定器
２切換スイッチ（切換手段）
３地絡抵抗
４電圧測定部（電圧測定手段）
５表示部（表示手段）
６警報部（警報発信手段）
７制御部（計時手段、演算部）
Ｄ直流回路
Ｒｐ正極側絶縁抵抗（値）
Ｒｎ負極側絶縁抵抗（値）
Ｃｐ正極側静電容量（値）
Ｃｎ負極側静電容量（値）
６４Ｄ直流制御回路地絡継電器 1 Insulation resistance measuring instrument 2 Changeover switch (switching means)
3 Ground fault resistance 4 Voltage measurement unit (voltage measurement means)
5 Display section (display means)
6 Alarm section (alarm transmission means)
7 Control unit (timer, calculation unit)
D DC circuit Rp Positive side insulation resistance (value)
Rn Negative side insulation resistance (value)
Cp Positive electrode side capacitance (value)
Cn Negative electrode side capacitance (value)
64D DC control circuit ground fault relay

Claims

An insulation resistance measuring instrument for measuring a ground insulation resistance value of a DC circuit,
A ground fault resistance switched between the positive electrode side and the ground of the DC circuit and between the negative electrode side and the ground via a switching means, a voltage measuring means for measuring a voltage between terminals of the ground fault resistance, and the voltage measuring means A calculation unit that calculates a ground insulation resistance value of the DC circuit based on the measured stable voltage value of the ground fault resistance,
Insulation resistance measuring instrument characterized by the above.

It has time measuring means for measuring a transient time until the terminal voltage of the ground fault resistance reaches a predetermined voltage, and based on the transient time measured by the time measuring means and the calculated ground insulation resistance value, The calculation unit calculates a ground capacitance value of the DC circuit,
The insulation resistance measuring device according to claim 1.

A capacitance measuring device for measuring a ground capacitance value of a DC circuit,
A ground fault resistor connected between the positive electrode side and the ground of the DC circuit or between the negative electrode side and the ground, a voltage measuring means for measuring a voltage between terminals of the ground fault resistor, and until the terminal voltage reaches a predetermined voltage. The ground capacitance value of the DC circuit is calculated based on the time measuring means for measuring the transient time of the DC circuit, and the transient time measured by the time measuring means and the ground insulation resistance value on the polarity side to which the ground fault resistance is connected. An arithmetic unit to
A capacitance measuring device characterized by that.

Display means for displaying a calculation result by the calculation unit;
The insulation resistance measuring device or capacitance measuring device according to any one of claims 1 to 3.

Having an alarm transmission means for transmitting an alarm, and transmitting an alarm when the calculated ground insulation resistance value or ground capacitance value is an abnormal value;
The insulation resistance measuring device or the capacitance measuring device according to any one of claims 1 to 4.

An insulation resistance measurement method for measuring a ground insulation resistance value of a DC circuit,
Connect a ground fault resistance between the positive side of the DC circuit and the ground, measure the positive side stable voltage value at which the terminal voltage of this ground fault resistance is stable,
Connect the ground fault resistance between the negative electrode side of the DC circuit and the ground, and measure the negative side stable voltage value at which the terminal voltage of the ground fault resistance is stabilized,
Based on the positive side stable voltage value and the negative side stable voltage value, the ground insulation resistance value of the DC circuit is calculated.
Insulation resistance measuring method characterized by the above.

Measure the transient time until the terminal voltage of the ground fault resistance reaches a predetermined voltage, and calculate the ground capacitance value of the DC circuit based on the transient time and the calculated ground insulation resistance value To
The insulation resistance measuring method according to claim 6.

A capacitance measuring method for measuring a ground capacitance value of a DC circuit,
A ground fault resistance is connected between the positive electrode side and the ground of the DC circuit or between the negative electrode side and the ground, and a transient time until the voltage between the terminals of the ground fault resistance reaches a predetermined voltage is measured. Based on the ground-side insulation resistance value on the polarity side to which the ground fault resistance is connected, the ground capacitance value of the DC circuit is calculated.
A capacitance measuring method characterized by the above.

The resistance value of the ground fault resistance is set to a high value that does not affect the DC circuit even if a ground fault occurs.
The insulation resistance measuring device, capacitance measuring device, insulation resistance measuring method or capacitance measuring method according to any one of claims 1 to 8.

In the insulation resistance measuring instrument or the insulation resistance measuring method according to any one of claims 1 to 9, wherein a stable voltage value of the ground fault resistance is measured.
The resistance value of the ground fault resistance is set so that the stable voltage value falls within a predetermined voltage range.
An insulation resistance measuring instrument or an insulation resistance measuring method.

In the insulation resistance measuring instrument, capacitance measuring instrument, insulation resistance measuring method or capacitance measuring method according to any one of claims 2 to 10, wherein the transient time is measured.
The resistance value of the ground fault resistance is set so that the transient time is within a predetermined time range.
An insulation resistance measuring device, a capacitance measuring device, an insulation resistance measuring method, or a capacitance measuring method.