JP6809189B2 - Insulation resistance measurement method for DC power supply circuit - Google Patents

Description

本発明は、電気所の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する複数の直流電源供給回路の合成絶縁抵抗を求める直流電源供給回路の絶縁抵抗測定方法に関する。 In the present invention, the insulation resistance of a DC power supply circuit for obtaining the combined insulation resistance of a plurality of DC power supply circuits that supply DC power from a DC power supply device to a control circuit for operating an electric facility of an electric station via a DC bus. Regarding the measurement method.

発変電所や開閉所等の電気所では、遮断器や断路器等の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する直流電源供給回路が設けられている。この直流電源供給回路は、直流電源装置が接続された直流母線から複数引き出され、さらに、直流電源供給回路から分岐して多数の直流負荷である制御回路に直流電源を供給する。 In electric stations such as power stations and switchyards, a DC power supply circuit that supplies DC power from a DC power supply device via a DC bus is provided in the control circuit for operating electrical equipment such as circuit breakers and circuit breakers. ing. A plurality of DC power supply circuits are drawn from the DC bus to which the DC power supply device is connected, and further branch off from the DC power supply circuit to supply DC power to a control circuit which is a large number of DC loads.

このような直流電源供給回路においては、直流電源供給回路の地絡故障を検出するための直流地絡継電器（６４Ｄ）が設置されている。直流地絡継電器は、直流電源供給回路の直流母線の正極と負極を抵抗分圧した分圧回路に設けられ、分圧回路の分圧中点は抵抗を介して接地されている。 In such a DC power supply circuit, a DC ground relay (64D) for detecting a ground fault in the DC power supply circuit is installed. The DC ground fault relay is provided in a voltage dividing circuit in which the positive and negative electrodes of the DC bus of the DC power supply circuit are divided by resistance, and the middle point of the voltage dividing circuit is grounded via a resistor.

このような直流電源供給回路においては、電気設備技術基準に従い、直流電源供給回路の絶縁抵抗値が規定値以上であることを管理している。絶縁抵抗の管理に当たっては、電気設備ごとに点検周期を設定し、定期点検の都度、電気設備の充電を停止し絶縁抵抗計にて絶縁抵抗値を測定している。 In such a DC power supply circuit, it is controlled that the insulation resistance value of the DC power supply circuit is equal to or higher than the specified value in accordance with the technical standards for electrical equipment. In managing the insulation resistance, an inspection cycle is set for each electrical equipment, charging of the electrical equipment is stopped each time the periodic inspection is performed, and the insulation resistance value is measured with an insulation resistance tester.

直流電源供給回路の絶縁抵抗を管理するものとして、直流回路の対地絶縁抵抗値を活線状態で常時計測して、計測値を連続的に表示することにより、直流回路の系統の保守点検を容易にしたものがある（例えば、特許文献１参照）。 As a means of managing the insulation resistance of the DC power supply circuit, the maintenance and inspection of the DC circuit system is easy by constantly measuring the ground insulation resistance value of the DC circuit in the live line state and continuously displaying the measured value. (See, for example, Patent Document 1).

特開平７−６３８０１号公報Japanese Unexamined Patent Publication No. 7-63801

しかし、定期点検の都度、絶縁抵抗計にて絶縁抵抗値を測定する方法では、電気設備の充電を停止する必要があり、停止した電気設備のみの絶縁抵抗値しか測定ができない。また、絶縁抵抗値の測定機会が定期点検の周期であるという制約があるため、周辺環境の変化、例えば気象条件を考慮した絶縁抵抗値の傾向を把握するのが難しい。 However, in the method of measuring the insulation resistance value with an insulation resistance meter each time a periodic inspection is performed, it is necessary to stop charging of the electrical equipment, and only the insulation resistance value of the stopped electrical equipment can be measured. In addition, it is difficult to grasp the tendency of the insulation resistance value in consideration of changes in the surrounding environment, for example, meteorological conditions, because there is a restriction that the measurement opportunity of the insulation resistance value is a periodic inspection cycle.

また、特許文献１のものでは、直流回路から直流電力の供給を受ける電力機器の運転を停止させることなく、活線状態で直流回路の正極側及び負極側の対地絶縁抵抗値を簡単に計測でき、絶縁抵抗値の傾向を把握できるが、絶縁抵抗の測定精度の向上が見込めない。絶縁抵抗に流れる電流は微少であり、漏洩電流を検出する漏洩電流計測手段（デジタルメータリレー）の測定精度に限界があるからである。また、直流地絡継電器は、直流回路の直流母線の正極と負極とを抵抗分圧した分圧回路に設けられ、分圧回路の分圧中点は抵抗を介して接地されているので、その接地点に漏洩電流が流れ込み、絶縁抵抗と対大地間との漏洩電流の測定精度が落ちる。 Further, in Patent Document 1, it is possible to easily measure the ground insulation resistance value of the positive electrode side and the negative electrode side of the DC circuit in the live wire state without stopping the operation of the power device that receives the DC power supplied from the DC circuit. , The tendency of the insulation resistance value can be grasped, but the measurement accuracy of the insulation resistance cannot be expected to be improved. This is because the current flowing through the insulation resistor is very small, and the measurement accuracy of the leakage current measuring means (digital meter relay) for detecting the leakage current is limited. Further, the DC ground relay is provided in the voltage dividing circuit in which the positive and negative sides of the DC bus of the DC circuit are divided by resistance, and the voltage dividing middle point of the voltage dividing circuit is grounded via the resistor. Leakage current flows into the grounding point, and the measurement accuracy of the leakage current between the insulation resistance and the ground is reduced.

本発明の目的は、電気所の電気設備を操作するための制御回路に直流電源を供給する複数の直流電源供給回路の合成絶縁抵抗を精度よく求めることできる直流電源供給回路の絶縁抵抗測定方法を提供することである。 An object of the present invention is a method for measuring the insulation resistance of a DC power supply circuit capable of accurately obtaining the combined insulation resistance of a plurality of DC power supply circuits that supply DC power to a control circuit for operating electrical equipment in an electric place. Is to provide.

請求項１の発明に係る直流電源供給回路の絶縁抵抗測定方法は、電気所の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する複数の直流電源供給回路のいずれかに地絡故障が発生したとき動作する直流地絡継電器をロックし、前記直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定し、前記Ｐ電線または前記Ｎ電線への接続を切り換えて前記Ｐ電線または前記Ｎ電線のいずれかを接地し前記Ｐ電線または前記Ｎ電線に流れる電流を検出する検出回路ユニットを前記Ｐ電線と前記Ｎ電線との間に接続し、前記検出回路ユニットに増幅器及び高感度直流電流クランプメータを接続すると共に高感度直流電流クランプメータにローパスフィルタを接続し、前記高感度直流クランプメータのゼロ点調整を行い前記Ｐ電線または前記Ｎ電線のうち絶縁抵抗を測定する側の反対側の電線を前記検出回路ユニットにより接地し、前記増幅器で増幅され前記高感度直流クランプメータで検出された前記Ｐ電線または前記Ｎ電線に流れる電流から前記ローパスフィルタで商用電源の周波数成分を除去した前記Ｐ電線または前記Ｎ電線に流れる直流分電流を測定し、前記ＰＮ電圧及び前記ローパスフィルタで得られた前記Ｐ電線または前記Ｎ電線に流れる直流分電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めることを特徴とする。 The method for measuring the insulation resistance of a DC power supply circuit according to the invention of claim 1 is to supply a plurality of DC power supplies from a DC power supply device to a control circuit for operating electrical equipment of an electric station via a DC bus. The DC ground fault relay that operates when a ground fault occurs in any of the circuits is locked, and the PN voltage between the positive P wire and the negative N wire connected to the DC power supply device is measured. The detection circuit unit that switches the connection to the P wire or the N wire to ground either the P wire or the N wire and detects the current flowing through the P wire or the N wire is the P wire and the N wire. The detection circuit unit is connected to an amplifier and a high-sensitivity DC current clamp meter, and a low-pass filter is connected to the high-sensitivity DC current clamp meter to adjust the zero point of the high-sensitivity DC clamp meter. The electric wire or the electric wire on the opposite side of the N electric wire on the side opposite to the side for measuring the insulation resistance is grounded by the detection circuit unit, amplified by the amplifier, and detected by the high-sensitivity DC clamp meter on the P electric wire or the N electric wire. The DC component current flowing through the P wire or the N wire from which the frequency component of the commercial power supply is removed from the flowing current is measured, and the PN voltage and the P wire or the N wire obtained by the low pass filter are measured. It is characterized in that the combined insulation resistance of a plurality of DC power supply circuits is obtained based on the flowing DC component current.

請求項２の発明に係る直流電源供給回路の絶縁抵抗測定方法は、電気所の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する複数の直流電源供給回路のいずれかに地絡故障が発生したとき動作する直流地絡継電器をロックし、前記直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定すると共に前記Ｐ電線と大地との間のＰＥ電圧及び前記Ｎ電線と大地との間のＮＥ電圧を測定し、前記ＰＥ電圧及び前記ＮＥ電圧に基づいて前記直流地絡継電器がロックされていることを確認し、前記Ｐ電線または前記Ｎ電線への接続を切り換えて前記Ｐ電線または前記Ｎ電線のいずれかを接地し前記Ｐ電線または前記Ｎ電線に流れる電流を検出する検出回路ユニットを前記Ｐ電線と前記Ｎ電線との間に接続し、前記検出回路ユニットに増幅器及び高感度直流電流クランプメータを接続すると共に高感度直流電流クランプメータにローパスフィルタを接続し、前記高感度直流クランプメータのゼロ点調整を行い前記Ｐ電線または前記Ｎ電線のうち絶縁抵抗を測定する側の反対側の電線を前記検出回路ユニットにより接地し、前記増幅器で増幅され前記高感度直流クランプメータで検出された前記Ｐ電線または前記Ｎ電線に流れる電流から前記ローパスフィルタで商用電源の周波数成分を除去した前記Ｐ電線または前記Ｎ電線に流れる直流分電流を測定し、前記ＰＮ電圧及び前記ローパスフィルタで得られた前記Ｐ電線または前記Ｎ電線に流れる直流分電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めることを特徴とする。 The method for measuring the insulation resistance of the DC power supply circuit according to the invention of claim 2 is to supply a plurality of DC power supplies from the DC power supply device to the control circuit for operating the electrical equipment of the electric station via the DC bus. The DC ground fault relay that operates when a ground fault occurs in any of the circuits is locked, and the PN voltage between the positive P wire and the negative N wire connected to the DC power supply device is measured and described above. The PE voltage between the P wire and the ground and the NE voltage between the N wire and the ground are measured, and it is confirmed that the DC ground fault relay is locked based on the PE voltage and the NE voltage. The detection circuit unit that switches the connection to the P wire or the N wire to ground either the P wire or the N wire and detects the current flowing through the P wire or the N wire is the P wire and the N. Connect to the wire, connect the amplifier and high-sensitivity DC current clamp meter to the detection circuit unit, connect the low-pass filter to the high-sensitivity DC current clamp meter, and adjust the zero point of the high-sensitivity DC clamp meter. The P wire or the N wire on the opposite side of the P wire or the N wire on the side opposite to the measurement of insulation resistance is grounded by the detection circuit unit, amplified by the amplifier, and detected by the high-sensitivity DC clamp meter. The DC component current flowing through the P wire or the N wire obtained by removing the frequency component of the commercial power supply from the current flowing through the wire is measured, and the PN voltage and the P wire or the N obtained by the low pass filter are measured. It is characterized in that the combined insulation resistance of a plurality of DC power supply circuits is obtained based on the DC component current flowing through the electric wire.

請求項１の発明によれば、絶縁抵抗の測定の際には直流地絡継電器をロックし、直流地絡継電器の分圧回路の分圧中点の接地点に漏洩電流が流れ込むのを防止するので、絶縁抵抗に流れる漏洩電流の検出精度が向上する。また、検出回路ユニットに増幅器を接続して漏洩電流を増幅し、漏洩電流を検出する直流電流クランプメータとして高感度直流電流クランプメータを使用するので、絶縁抵抗に流れる漏洩電流の検出精度が向上する。さらには、高感度直流電流クランプメータにローパスフィルタを接続するので、Ｐ電線またはＮ電線に流れる漏洩電流に重畳する商用電源の周波数成分を除去でき、漏洩電流の直流分成分だけを抽出できる。そして、検出したＰＮ電圧及びローパスフィルタで得られたＰ電線またはＮ電線に流れる電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めるので、測定精度の良い絶縁抵抗を得ることができる。 According to the invention of claim 1, when measuring the insulation resistance, the DC ground relay is locked to prevent the leakage current from flowing into the grounding point at the voltage dividing midpoint of the voltage dividing circuit of the DC ground relay. Therefore, the detection accuracy of the leakage current flowing through the insulation resistor is improved. In addition, since a high-sensitivity DC current clamp meter is used as a DC current clamp meter that amplifies the leakage current by connecting an amplifier to the detection circuit unit and detects the leakage current, the detection accuracy of the leakage current flowing through the insulation resistance is improved. .. Furthermore, since the low-pass filter is connected to the high-sensitivity DC current clamp meter, the frequency component of the commercial power supply superimposed on the leakage current flowing through the P wire or N wire can be removed, and only the DC component of the leakage current can be extracted. Then, since the combined insulation resistance of the plurality of DC power supply circuits is obtained based on the detected PN voltage and the current flowing through the P wire or the N wire obtained by the low-pass filter, it is possible to obtain an insulation resistance with good measurement accuracy.

請求項２の発明によれば、請求項１の発明の効果に加え、ＰＥ電圧及びＮＥ電圧に基づいて直流地絡継電器がロックされていることを確認するので、直流地絡継電器の分圧回路の分圧中点に漏洩電流が流れ込む状態で絶縁抵抗の測定を行うことがなくなる。従って、絶縁抵抗の測定精度が高まる。 According to the invention of claim 2, in addition to the effect of the invention of claim 1, it is confirmed that the DC ground relay is locked based on the PE voltage and the NE voltage, so that the voltage divider circuit of the DC ground relay is used. It is no longer necessary to measure the insulation resistance when the leakage current flows into the middle point of the voltage division. Therefore, the measurement accuracy of the insulation resistance is improved.

本発明の第１実施形態に係る直流電源供給回路の絶縁抵抗測定方法の工程を示すフローチャート。The flowchart which shows the process of the insulation resistance measurement method of the DC power supply circuit which concerns on 1st Embodiment of this invention. 本発明の直流電源供給回路の絶縁抵抗測定方法が適用される電気所の電気設備の直流回路の概略構成を示すブロック図。The block diagram which shows the schematic structure of the DC circuit of the electric equipment of the electric place to which the insulation resistance measuring method of the DC power supply circuit of this invention is applied. 本発明の直流電源供給回路の絶縁抵抗測定方法が適用される電気所の電気設備の直流回路の等価回路図。The equivalent circuit diagram of the DC circuit of the electric equipment of the electric place to which the insulation resistance measuring method of the DC power supply circuit of this invention is applied. 図３の等価回路に、検出回路ユニット、増幅器、高感度直流電流クランプメータ、ローパスフィルタを接続した状態を示す回路図。A circuit diagram showing a state in which a detection circuit unit, an amplifier, a high-sensitivity DC current clamp meter, and a low-pass filter are connected to the equivalent circuit of FIG. 図４の回路において負極のＮ電線の絶縁抵抗ＲＮを求める場合の回路図。The circuit diagram in the case of obtaining the insulation resistance RN of the N electric wire of a negative electrode in the circuit of FIG. 図４の回路において正極のＰ電線の絶縁抵抗ＲＰを求める場合の回路図。The circuit diagram in the case of obtaining the insulation resistance RP of the positive electrode P electric wire in the circuit of FIG. 本発明の実施形態の高感度直流電流クランプメータで測定された漏洩電流の一例を示す波形図。The waveform diagram which shows an example of the leakage current measured by the high-sensitivity DC current clamp meter of embodiment of this invention. 本発明の実施形態のローパスフィルタで商用電源の周波数成分の電流を除去した後の漏洩電流の一例を示す波形図。The waveform diagram which shows an example of the leakage current after removing the current of the frequency component of the commercial power source by the low-pass filter of embodiment of this invention. 本発明の実施形態で測定した絶縁抵抗の誤差率を示すグラフ。The graph which shows the error rate of the insulation resistance measured by the embodiment of this invention. 本発明の第２実施形態に係る直流電源供給回路の絶縁抵抗測定方法の工程を示すフローチャート。The flowchart which shows the process of the insulation resistance measurement method of the DC power supply circuit which concerns on 2nd Embodiment of this invention.

以下、本発明の実施形態を説明する。図１は本発明の第１実施形態に係る直流電源供給回路の絶縁抵抗測定方法の工程を示すフローチャートである。また、図２は本発明の直流電源供給回路の絶縁抵抗測定方法が適用される電気所の電気設備の直流回路の概略構成を示すブロック図、図３は本発明の直流電源供給回路の絶縁抵抗測定方法が適用される電気所の電気設備の直流回路の等価回路図である。 Hereinafter, embodiments of the present invention will be described. FIG. 1 is a flowchart showing a process of a method for measuring insulation resistance of a DC power supply circuit according to a first embodiment of the present invention. Further, FIG. 2 is a block diagram showing a schematic configuration of a DC circuit of an electric facility of an electric place to which the method for measuring the insulation resistance of the DC power supply circuit of the present invention is applied, and FIG. 3 is an insulation resistance of the DC power supply circuit of the present invention. It is an equivalent circuit diagram of the DC circuit of the electric equipment of the electric place to which the measuring method is applied.

図２において、電気所の電気設備の直流回路は、直流電源装置１１が直流母線１２を介して複数の直流電源供給回路１３に接続され、複数の直流電源供給回路１３から電気所の電気設備を操作するための制御回路に直流電源装置１１からの直流電源を供給する。図２では、複数の直流電源供給回路１３として３個の直流電源供給回路１３を示している。直流母線１２には、いずれかの直流電源供給回路１３に地絡故障が発生したことを検出するための直流地絡継電器１４が設置されている。 In FIG. 2, in the DC circuit of the electrical equipment of the electric station, the DC power supply device 11 is connected to the plurality of DC power supply circuits 13 via the DC bus 12, and the electrical equipment of the electric station is connected from the plurality of DC power supply circuits 13. The DC power supply from the DC power supply device 11 is supplied to the control circuit for operation. FIG. 2 shows three DC power supply circuits 13 as a plurality of DC power supply circuits 13. The DC bus 12 is provided with a DC ground relay relay 14 for detecting that a ground fault has occurred in any of the DC power supply circuits 13.

図３において、図２に示した複数の直流電源供給回路１３を並列接続して形成された回路を１つの直流電源供給回路１３として等価回路で示している。すなわち、等価回路は直流母線１２に１つの直流電源供給回路１３が接続された構成となっている。直流電源装置１１は、直流母線１２の正極のＰ電線１５と負極のＮ電線１６との間に接続され、直流母線１２には直流地絡継電器１４が接続されている。直流地絡継電器１４は、直流回路の直流母線１２の正極と負極とを抵抗分圧した分圧回路１７に設けられ、分圧回路１７の分圧中点は抵抗及び開閉スイッチ１８を介して接地されている。 In FIG. 3, a circuit formed by connecting a plurality of DC power supply circuits 13 shown in FIG. 2 in parallel is shown as one DC power supply circuit 13 as an equivalent circuit. That is, the equivalent circuit has a configuration in which one DC power supply circuit 13 is connected to the DC bus 12. The DC power supply device 11 is connected between the P wire 15 of the positive electrode of the DC bus 12 and the N wire 16 of the negative electrode, and the DC ground relay 14 is connected to the DC bus 12. The DC ground fault relay 14 is provided in a voltage dividing circuit 17 in which the positive and negative electrodes of the DC bus 12 of the DC circuit are divided by resistance, and the voltage dividing midpoint of the voltage dividing circuit 17 is grounded via a resistor and an open / close switch 18. Has been done.

図３では、直流母線１２に１つの直流電源供給回路１３が接続された構成となっていることから、正極のＰ電線１５の絶縁抵抗ＲＰは複数の直流電源供給回路１３の正極側の合成絶縁抵抗であり、負極のＮ電線１６の絶縁抵抗ＲＮは複数の直流電源供給回路１３の負極側の合成絶縁抵抗である。また、Ｐ電線１５は対地静電容量ＣＰを有しＮ電線１６は対地静電容量ＣＮを有する。また、Ｐ電線１５にはＰ電線１５に接続するためのＰ端子１９が設けられ、Ｎ電線１６にはＮ電線１６に接続するためのＮ端子２０が設けられている。さらに、大地に接地するためのＥ端子２１が用意されている。 In FIG. 3, since one DC power supply circuit 13 is connected to the DC bus 12, the insulation resistance RP of the P wire 15 of the positive electrode is the composite insulation of the positive electrode side of the plurality of DC power supply circuits 13. It is a resistance, and the insulation resistance RN of the N electric wire 16 of the negative electrode is a combined insulation resistance on the negative electrode side of the plurality of DC power supply circuits 13. Further, the P wire 15 has a ground capacitance CP, and the N wire 16 has a ground capacitance CN. Further, the P electric wire 15 is provided with a P terminal 19 for connecting to the P electric wire 15, and the N electric wire 16 is provided with an N terminal 20 for connecting to the N electric wire 16. Further, an E terminal 21 for grounding to the ground is prepared.

これらＰ端子１９、Ｎ端子２０及びＥ端子２１は、電気所の電気設備の直流給回路の作業用分電盤や直流母線１２などに設けられている。正極のＰ電線１５の絶縁抵抗ＲＰを求めるにあたっては、Ｎ端子２０とＥ端子２１とを接続してＮ線路を接地して、直流電源装置１１から絶縁抵抗ＲＰに流れる漏洩電流を測定し、直流電源装置１１のＰＮ電圧と絶縁抵抗ＲＰを流れる漏洩電流とから絶縁抵抗ＲＰを求めることになる。同様に、負極のＮ電線１６の絶縁抵抗ＲＮを求めるにあたっては、Ｐ端子１９とＥ端子２１とを接続してＰ線路を接地して、直流電源装置１１から絶縁抵抗ＲＮに流れる漏洩電流を測定し、直流電源装置１１のＰＮ電圧と絶縁抵抗ＲＮを流れる漏洩電流とから絶縁抵抗ＲＮを求めることになる。これにより、直流回路が活線状態であっても絶縁抵抗ＲＰまたは絶縁抵抗ＲＮを測定できる。つまり、電気設備の充電を停止しなくても直流回路の絶縁抵抗の測定ができる。 These P terminal 19, N terminal 20, and E terminal 21 are provided on a work distribution board, a DC bus 12, or the like of a DC supply circuit of an electric facility of an electric station. In obtaining the insulation resistance RP of the positive P wire 15, the N terminal 20 and the E terminal 21 are connected, the N line is grounded, the leakage current flowing from the DC power supply device 11 to the insulation resistance RP is measured, and DC is obtained. The insulation resistance RP is obtained from the PN voltage of the power supply device 11 and the leakage current flowing through the insulation resistance RP. Similarly, when determining the insulation resistance RN of the negative N wire 16, the P terminal 19 and the E terminal 21 are connected, the P line is grounded, and the leakage current flowing from the DC power supply device 11 to the insulation resistance RN is measured. Then, the insulation resistance RN is obtained from the PN voltage of the DC power supply device 11 and the leakage current flowing through the insulation resistance RN. Thereby, the insulation resistance RP or the insulation resistance RN can be measured even when the DC circuit is in a live-line state. That is, the insulation resistance of the DC circuit can be measured without stopping the charging of the electrical equipment.

このように、絶縁抵抗ＲＰまたは絶縁抵抗ＲＮを求めるにあたってはＥ端子２１を接地することになるから、もし、漏洩電流が大きい場合には直流電源供給回路を通して制御回路に漏洩電流が流れ込むことになり、制御回路内に電気所の電気機器を操作するリレーが接地して接続されている場合には、そのリレーを誤動作させる可能性がある。 In this way, since the E terminal 21 is grounded when obtaining the insulation resistance RP or the insulation resistance RN, if the leakage current is large, the leakage current will flow into the control circuit through the DC power supply circuit. If a relay that operates an electric device in an electric place is grounded and connected in the control circuit, the relay may malfunction.

そこで、後述のように、Ｐ電線１５またはＮ電線１６への接続を切り換えてＰ電線１５またはＮ電線１６のいずれかを接地し、Ｐ電線１５またはＮ電線１６に流れる電流を検出するための検出回路ユニット内に、Ｅ端子２１に流れる電流を所定値以下に制限する限流抵抗ｒを設ける。これにより、Ｅ端子２１に流れる漏洩電流の大きさは制御回路が誤動作しない程度の大きさに制限される。 Therefore, as will be described later, detection for switching the connection to the P wire 15 or the N wire 16 to ground either the P wire 15 or the N wire 16 and detecting the current flowing through the P wire 15 or the N wire 16. A current limiting resistor r is provided in the circuit unit to limit the current flowing through the E terminal 21 to a predetermined value or less. As a result, the magnitude of the leakage current flowing through the E terminal 21 is limited to such a magnitude that the control circuit does not malfunction.

図１において、図３に示す直流回路の絶縁抵抗ＲＰまたは絶縁抵抗ＮＰを測定するにあたっては、まず、直流地絡継電器をロックする（Ｓ１）。直流地絡継電器１４をロックするのは以下の理由による。図３に示すように、直流地絡継電器１４は、直流回路の直流母線１２の正極と負極とを抵抗分圧した分圧回路１５に設けられ、直流回路が活線状態では、分圧回路１５の分圧中点は開閉スイッチ１８はオンしており接地されている。開閉スイッチ１８がオンしていると分圧回路１５の分圧中点は接地された状態であるので、その接地点に漏洩電流が流れ込み、漏洩電流は絶縁抵抗ＲＰまたは絶縁抵抗ＮＰと対大地間の漏洩電流だけではなくなり、絶縁抵抗ＲＰまたは絶縁抵抗ＮＰを測定するのに適した漏洩電流を検出することができなくなるからである。そこで、開閉スイッチ１８をオフとし直流地絡継電器１４をロックする。 In FIG. 1, when measuring the insulation resistance RP or insulation resistance NP of the DC circuit shown in FIG. 3, first, the DC ground relay is locked (S1). The DC ground relay 14 is locked for the following reasons. As shown in FIG. 3, the DC ground fault relay 14 is provided in the voltage dividing circuit 15 in which the positive and negative electrodes of the DC bus 12 of the DC circuit are divided by resistance, and when the DC circuit is in the active line state, the voltage dividing circuit 15 At the middle point of voltage division, the open / close switch 18 is on and is grounded. When the open / close switch 18 is on, the voltage dividing midpoint of the voltage dividing circuit 15 is in a grounded state, so a leakage current flows into the grounding point, and the leakage current is between the insulation resistance RP or insulation resistance NP and the ground. This is because not only the leakage current of the above, but also the leakage current suitable for measuring the insulation resistance RP or the insulation resistance NP cannot be detected. Therefore, the open / close switch 18 is turned off and the DC ground relay is locked.

次に、図１において、直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定する（Ｓ２）。図３のＰ端子１９とＮ端子２０との間に電圧測定器を接続してＰＮ電圧を測定する。そして、検出回路ユニットをＰ電線とＮ電線との間に接続し（Ｓ３）、検出回路ユニットに増幅器及び高感度直流電流クランプメータを接続すると共に高感度直流電流クランプメータにローパスフィルタを接続する（Ｓ４）。 Next, in FIG. 1, the PN voltage between the positive electrode P wire and the negative electrode N wire connected to the DC power supply device is measured (S2). A voltage measuring device is connected between the P terminal 19 and the N terminal 20 in FIG. 3 to measure the PN voltage. Then, the detection circuit unit is connected between the P wire and the N wire (S3), the amplifier and the high-sensitivity DC current clamp meter are connected to the detection circuit unit, and the low-pass filter is connected to the high-sensitivity DC current clamp meter (S3). S4).

図４は、図３の等価回路に、検出回路ユニット、増幅器、高感度直流電流クランプメータ、ローパスフィルタを接続した状態を示す回路図である。図４において、検出回路ユニット２２は、Ｐ電線１５またはＮ電線１６への接続を切り換えてＰ電線１５またはＮ電線１６のいずれかを接地し、Ｐ電線１５またはＮ電線１６に流れる電流を検出するものである。すなわち、検出回路ユニット２２は、Ｐ電線１５のＰ端子１９及びＮ電線１６のＮ端子２０の間に接続され、また大地に接地するためのＥ端子２１に接続される。Ｅ端子２１には、前述したように制限抵抗ｒが接続される。また、検出回路ユニット２２は切換スイッチ２３を有し、切換スイッチ２３によりＰ電線１５またはＮ電線１６への接続を切り換えてＰ電線１５またはＮ電線１６のいずれかを接地する。 FIG. 4 is a circuit diagram showing a state in which a detection circuit unit, an amplifier, a high-sensitivity DC current clamp meter, and a low-pass filter are connected to the equivalent circuit of FIG. In FIG. 4, the detection circuit unit 22 switches the connection to the P wire 15 or the N wire 16 to ground either the P wire 15 or the N wire 16 and detects the current flowing through the P wire 15 or the N wire 16. It is a thing. That is, the detection circuit unit 22 is connected between the P terminal 19 of the P electric wire 15 and the N terminal 20 of the N electric wire 16, and is also connected to the E terminal 21 for grounding to the ground. As described above, the limiting resistor r is connected to the E terminal 21. Further, the detection circuit unit 22 has a changeover switch 23, and the changeover switch 23 switches the connection to the P wire 15 or the N wire 16 to ground either the P wire 15 or the N wire 16.

増幅器２４は、直流電源装置１１からＰ電線１５またはＮ電線１６を通って大地に接地するためのＥ端子２１に流れる電流を増幅するものである。増幅器２４は巻線で構成され巻線の巻数ｎに比例して電流を増幅する。直流電源装置１１からＰ電線１５を通ってＥ端子２１に流れる電流は絶縁抵抗ＲＮ及び対地静電容量ＣＮに流れる漏洩電流であり、直流電源装置１１からＮ電線１６を通ってＥ端子２１に流れる電流は絶縁抵抗ＲＰ及び対地静電容量ＣＰに流れる漏洩電流である。 The amplifier 24 amplifies the current flowing from the DC power supply device 11 to the E terminal 21 for grounding to the ground through the P electric wire 15 or the N electric wire 16. The amplifier 24 is composed of windings and amplifies the current in proportion to the number of turns n of the windings. The current flowing from the DC power supply device 11 through the P electric wire 15 to the E terminal 21 is a leakage current flowing through the insulation resistance RN and the capacitance CN to the ground, and flows from the DC power supply device 11 to the E terminal 21 through the N electric wire 16. The current is a leakage current flowing through the insulation resistance RP and the capacitance CP to the ground.

増幅器２４で増幅された漏洩電流は、高感度直流電流クランプメータ２５に入力される。高感度直流電流クランプメータ２５としては、市販のもの（共立電気計器株式会社製、ＣＤミリアンペアクランプメータ、ＫＥＷ２５００、測定範囲１０μ〜１２０ｍＡ）を採用する。高感度直流電流クランプメータ２５で測定された漏洩電流は、商用電源の周波数成分を除去するためのローパスフィルタ２６を介して電流測定器２７に出力される。 The leakage current amplified by the amplifier 24 is input to the high-sensitivity DC current clamp meter 25. As the high-sensitivity DC current clamp meter 25, a commercially available one (manufactured by Kyoritsu Electric Meter Co., Ltd., CD milliamp clamp meter, KEW2500, measuring range of 10 μ to 120 mA) is adopted. The leakage current measured by the high-sensitivity DC current clamp meter 25 is output to the current measuring device 27 via the low-pass filter 26 for removing the frequency component of the commercial power supply.

図１のステップＳ３において、検出回路ユニット２２をＰ電線１５とＮ電線１６との間に接続し、図１のステップＳ４において、検出回路ユニット２２に増幅器２４及び高感度直流電流クランプメータ２５を接続すると共にローパスフィルタ２６を接続した後に、高感度直流クランプメータのゼロ点調整を行いＰ電線またはＮ電線のうち絶縁抵抗を測定する側の反対側の電線を検出回路ユニットにより接地する（Ｓ５）。 In step S3 of FIG. 1, the detection circuit unit 22 is connected between the P wire 15 and the N wire 16, and in step S4 of FIG. 1, the amplifier 24 and the high-sensitivity DC current clamp meter 25 are connected to the detection circuit unit 22. After connecting the low-pass filter 26, the zero point of the high-sensitivity DC clamp meter is adjusted, and the wire on the opposite side of the P wire or N wire on the side where the insulation resistance is measured is grounded by the detection circuit unit (S5).

ここで高感度直流電流クランプメータ２５は測定精度を安定させるために事前に電源を入れておくことが望ましい。そこで、図１のステップＳ４の段階で、つまり、増幅器２４に高感度直流電流クランプメータ２５を設置する段階で高感度直流電流クランプメータ２５の電源を入れておく。 Here, it is desirable that the high-sensitivity DC current clamp meter 25 is turned on in advance in order to stabilize the measurement accuracy. Therefore, the power of the high-sensitivity DC current clamp meter 25 is turned on at the stage of step S4 of FIG. 1, that is, at the stage of installing the high-sensitivity DC current clamp meter 25 in the amplifier 24.

図５は、図４の回路において負極のＮ電線の絶縁抵抗ＲＮを求める場合の回路図である。負極のＮ電線１６の絶縁抵抗ＲＮを求めるにあたっては、絶縁抵抗ＲＮを測定する側の反対側のＰ電線１５を接地する。すなわち、切換スイッチ２３をＰ端子１９に接続し、Ｐ端子１９とＥ端子２１とを接続してＰ線路１５を接地する。これにより、図５の点線で示すように、直流電源装置１１→Ｐ電線１５→Ｐ端子１９→切換スイッチ２３→Ｅ端子２１→大地→絶縁抵抗ＲＮと対地静電容量ＣＮとの並列回路→直流電源装置１１の回路が形成される。 FIG. 5 is a circuit diagram in the case of obtaining the insulation resistance RN of the negative electrode N electric wire in the circuit of FIG. In determining the insulation resistance RN of the negative electrode N wire 16, the P wire 15 on the opposite side to the side where the insulation resistance RN is measured is grounded. That is, the changeover switch 23 is connected to the P terminal 19, the P terminal 19 and the E terminal 21 are connected, and the P line 15 is grounded. As a result, as shown by the dotted line in FIG. 5, the DC power supply device 11 → P electric wire 15 → P terminal 19 → selector switch 23 → E terminal 21 → ground → parallel circuit of insulation resistance RN and capacitance CN to ground → DC The circuit of the power supply device 11 is formed.

図６は、図４の回路において正極のＰ電線の絶縁抵抗ＲＰを求める場合の回路図である。正極のＰ電線１５の絶縁抵抗ＲＰを求めるにあたっては、絶縁抵抗ＲＰを測定する側の反対側のＮ電線１６を接地する。すなわち、切換スイッチ２３をＮ端子１９に接続し、Ｎ端子２０とＥ端子２１とを接続してＮ線路１６を接地する。これにより、図６の点線で示すように、直流電源装置１１→Ｐ電線１５→絶縁抵抗ＲＰと対地静電容量ＣＰとの並列回路→大地→Ｅ端子２１→切換スイッチ２３→Ｎ端子２０→直流電源装置１１の回路が形成される。 FIG. 6 is a circuit diagram in the case of obtaining the insulation resistance RP of the P wire of the positive electrode in the circuit of FIG. In obtaining the insulation resistance RP of the P wire 15 of the positive electrode, the N wire 16 on the opposite side to the side where the insulation resistance RP is measured is grounded. That is, the changeover switch 23 is connected to the N terminal 19, the N terminal 20 and the E terminal 21 are connected, and the N line 16 is grounded. As a result, as shown by the dotted line in FIG. 6, the DC power supply device 11 → P electric wire 15 → parallel circuit of the insulation resistance RP and the capacitance CP to the ground → ground → E terminal 21 → changeover switch 23 → N terminal 20 → DC The circuit of the power supply device 11 is formed.

ここで、高感度直流電流クランプメータ２４のゼロ点調整を行うのは、高感度直流電流クランプメータ２４は２次側に交流バイアスを流して直流の電流を検出するものであることから、ゼロ点オフセットを補正するために測定の度にゼロ点調整を必要とするからである。 Here, the zero point of the high-sensitivity direct current clamp meter 24 is adjusted because the high-sensitivity direct current clamp meter 24 detects the direct current by applying an AC bias to the secondary side. This is because the zero point adjustment is required for each measurement in order to correct the offset.

図１のステップＳ５において、高感度直流クランプメータのゼロ点調整を行い、Ｐ電線またはＮ電線のうち絶縁抵抗を測定する側の反対側の電線を検出回路ユニットにより接地した後に、増幅器で増幅され高感度直流クランプメータで検出されたＰ電線またはＮ電線に流れる電流からローパスフィルタで商用電源の周波数成分を除去したＰ電線または前記Ｎ電線に流れる直流分電流を測定する（Ｓ６）。 In step S5 of FIG. 1, the zero point of the high-sensitivity DC clamp meter is adjusted, the wire on the opposite side of the P wire or N wire on the side where the insulation resistance is measured is grounded by the detection circuit unit, and then amplified by the amplifier. The DC component current flowing through the P wire or the N wire obtained by removing the frequency component of the commercial power supply from the current flowing through the P wire or the N wire detected by the high-sensitivity DC clamp meter is measured (S6).

図５、図６において、増幅器２４は、直流電源装置１１からＰ電線１５またはＮ電線１６を通って大地に接地するためのＥ端子２１に流れる電流を増幅する。これは、Ｐ電線１５の絶縁抵抗ＲＰまたはＮ電線１６の絶縁抵抗ＲＮに流れる漏洩電流の検出精度を向上させるためである。前述したように、本発明の実施形態で使用する高感度直流クランプメータ２５の測定範囲は１０μ〜１２０ｍＡであり、測定範囲は高感度ではあるが、増幅器２４を設けて、さらに検出精度を高めている。すなわち、Ｐ電線１５の絶縁抵抗ＲＰまたはＮ電線１６の絶縁抵抗ＲＮの健全な抵抗値は、１５〜２０ＭΩであり、直流電源装置１１のＰＮ電圧は通常１１０Ｖである。従って、健全な絶縁抵抗ＲＰまたは絶縁抵抗ＲＮに流れる電流は５．５μ〜７．３μＡであり、高感度直流クランプメータ２５の測定範囲１０μ〜１２０ｍＡより小さい値であるから、これに対応できるようにするためである。 In FIGS. 5 and 6, the amplifier 24 amplifies the current flowing from the DC power supply device 11 to the E terminal 21 for grounding to the ground through the P wire 15 or the N wire 16. This is to improve the detection accuracy of the leakage current flowing through the insulation resistance RP of the P wire 15 or the insulation resistance RN of the N wire 16. As described above, the measurement range of the high-sensitivity DC clamp meter 25 used in the embodiment of the present invention is 10 μ to 120 mA, and although the measurement range is high sensitivity, an amplifier 24 is provided to further improve the detection accuracy. There is. That is, the sound resistance value of the insulation resistance RP of the P wire 15 or the insulation resistance RN of the N wire 16 is 15 to 20 MΩ, and the PN voltage of the DC power supply device 11 is usually 110 V. Therefore, the current flowing through the sound insulation resistance RP or insulation resistance RN is 5.5μ to 7.3μA, which is smaller than the measurement range of the high-sensitivity DC clamp meter 25, which is 10μ to 120mA. To do.

増幅器２４は巻線で構成され巻線の巻数ｎに比例して電流を増幅するので、本発明の実施形態では、例えば巻数ｎを１００として１００倍の検出精度とする。これにより、増幅器２４及び高感度直流電流クランプメータ２５により、０．１μ〜１．２ｍＡの漏洩電流が測定できることになる。 Since the amplifier 24 is composed of windings and amplifies the current in proportion to the number of turns n of the windings, in the embodiment of the present invention, for example, the number of turns n is set to 100 to obtain 100 times the detection accuracy. As a result, the leakage current of 0.1 μ to 1.2 mA can be measured by the amplifier 24 and the high-sensitivity DC current clamp meter 25.

高感度直流電流クランプメータ２５で測定された漏洩電流には、Ｐ電線１５が対地静電容量ＣＰを有し、Ｎ電線１６が対地静電容量ＣＮを有することから、Ｐ電線１５を接地したときは対地静電容量ＣＮに流れる過渡電流が含まれ、同様に、Ｎ電線１６を接地したときは対地静電容量ＣＰに流れる過渡電流が含まれる。そこで、この過渡電流が流れなくなった後の安定した電流を測定対象とする。 The leakage current measured by the high-sensitivity DC current clamp meter 25 includes the P wire 15 having a capacitance CP to the ground and the N wire 16 having a capacitance CN to the ground. Therefore, when the P wire 15 is grounded. Includes a transient current flowing through the ground capacitance CN, and similarly includes a transient current flowing through the ground capacitance CP when the N wire 16 is grounded. Therefore, the stable current after the transient current stops flowing is set as the measurement target.

高感度直流電流クランプメータ２５で測定された漏洩電流は、ローパスフィルタ２６を介して電流測定器２７に出力される。ローパスフィルタ２６は、Ｐ電線１５またはＮ電線１６に重畳する商用電源の周波数成分の電流を除去するものである。図７は、高感度直流電流クランプメータ２５で測定された漏洩電流の一例を示す波形図である。図７では、対地静電容量ＣＰや対地静電容量ＣＮに流れる過渡電流の図示は省略している。図７に示すように、高感度直流電流クランプメータ２５で測定された漏洩電流には、Ｐ電線１５またはＮ電線１６に商用電源の周波数成分の電流が重畳しているので、ローパスフィルタ２６で商用電源の周波数成分の電流を除去する。図８はローパスフィルタ２６で商用電源の周波数成分の電流を除去した後の漏洩電流の一例を示す波形図である。このローパスフィルタ２６で得られたＰ電線１５またはＮ電線１６に流れる直流分電流は電流測定器１７に入力され、電流測定器１７でＰ電線１５またはＮ電線１６に流れる直流分電流の電流が測定される。この電流は、絶縁抵抗ＲＰまたは絶縁抵抗ＲＮに流れる漏洩電流である。 The leakage current measured by the high-sensitivity DC current clamp meter 25 is output to the current measuring device 27 via the low-pass filter 26. The low-pass filter 26 removes the current of the frequency component of the commercial power source superimposed on the P electric wire 15 or the N electric wire 16. FIG. 7 is a waveform diagram showing an example of the leakage current measured by the high-sensitivity DC current clamp meter 25. In FIG. 7, the transient current flowing through the ground capacitance CP and the ground capacitance CN is not shown. As shown in FIG. 7, since the current of the frequency component of the commercial power supply is superimposed on the P wire 15 or the N wire 16 in the leakage current measured by the high-sensitivity DC current clamp meter 25, it is commercialized by the low-pass filter 26. Remove the current of the frequency component of the power supply. FIG. 8 is a waveform diagram showing an example of leakage current after removing the current of the frequency component of the commercial power supply with the low-pass filter 26. The DC component current flowing through the P wire 15 or N wire 16 obtained by the low-pass filter 26 is input to the current measuring device 17, and the current of the DC component current flowing through the P wire 15 or N wire 16 is measured by the current measuring device 17. Will be done. This current is a leakage current flowing through the insulation resistance RP or the insulation resistance RN.

図１のステップＳ６において、増幅器で増幅され高感度直流クランプメータで検出されたＰ電線またはＮ電線に流れる電流からローパスフィルタで商用電源の周波数成分を除去したＰ電線または前記Ｎ電線に流れる直流分電流を測定した後に、ＰＮ電圧及びローパスフィルタで得られたＰ電線またはＮ電線に流れる直流分電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求める（Ｓ７）。 In step S6 of FIG. 1, the DC component flowing through the P wire or the N wire obtained by removing the frequency component of the commercial power supply from the current flowing through the P wire or N wire amplified by the amplifier and detected by the high-sensitivity DC clamp meter with a low-pass filter. After measuring the current, the combined insulation resistance of a plurality of DC power supply circuits is obtained based on the PN voltage and the DC component current flowing through the P wire or N wire obtained by the low-pass filter (S7).

ＰＮ電圧は、ステップＳ２において求められ、Ｐ電線に流れる直流分電流またはＮ電線に流れる直流分電流はステップＳ７で求められていることから、絶縁抵抗ＲＰは、絶縁抵抗ＲＰ＝ＰＮ電圧／Ｐ電線に流れる直流分電流、絶縁抵抗ＲＮは、絶縁抵抗ＲＮ＝ＰＮ電圧／Ｎ電線に流れる直流分電流で求めることができる。 Since the PN voltage is obtained in step S2 and the DC component current flowing through the P wire or the DC component current flowing through the N wire is obtained in step S7, the insulation resistance RP is the insulation resistance RP = PN voltage / P wire. The DC component current flowing through the circuit and the insulation resistance RN can be determined by the DC component current flowing through the insulation resistance RN = PN voltage / N wire.

図９は、本発明の実施形態で測定した絶縁抵抗の誤差率を示すグラフである。いま、本発明の実施形態で測定した絶縁抵抗をＲ１、絶縁抵抗計で測定した絶縁抵抗をＲ０とすると、誤差率は、（絶縁抵抗Ｒ１−絶縁抵抗Ｒ０）／絶縁抵抗Ｒ０で示される。図９から分かるように、１００ＭΩ以下では誤差率５％以下であり、４０ＭΩ以下では誤差率２〜３％以下である。絶縁抵抗が大きくなる程、つまり漏洩電流が小さくなる程、誤差率は大きくなる傾向にあるが、前述したように、Ｐ電線１５の絶縁抵抗ＲＰまたはＮ電線１６の絶縁抵抗ＲＮの健全な抵抗値は１５〜２０ＭΩであるので、実用上は高精度で絶縁抵抗が測定できることが分かる。 FIG. 9 is a graph showing the error rate of the insulation resistance measured in the embodiment of the present invention. Now, assuming that the insulation resistance measured in the embodiment of the present invention is R1 and the insulation resistance measured by an insulation resistance tester is R0, the error rate is indicated by (insulation resistance R1-insulation resistance R0) / insulation resistance R0. As can be seen from FIG. 9, the error rate is 5% or less at 100 MΩ or less, and the error rate is 2 to 3% or less at 40 MΩ or less. The error rate tends to increase as the insulation resistance increases, that is, as the leakage current decreases. However, as described above, the sound resistance value of the insulation resistance RP of the P wire 15 or the insulation resistance RN of the N wire 16 Is 15 to 20 MΩ, so it can be seen that the insulation resistance can be measured with high accuracy in practical use.

第１実施形態によれば、Ｐ電線１５の絶縁抵抗ＲＰまたはＮ電線１６の絶縁抵抗ＲＮを求めるにあたっては、Ｅ端子２１を接地し、直流電源装置１１から絶縁抵抗ＲＰまたは絶縁抵抗ＲＮに流れる漏洩電流を計測して絶縁抵抗ＲＰまたはＮ電線１６の絶縁抵抗ＲＮを求めるので、電気設備の使用中に絶縁抵抗の測定ができ、短時間で電気設備の直流回路のすべての合成絶縁抵抗を測定することができる。また、絶縁抵抗の測定機会に制約がないので、測定回数を増やすことにより絶縁抵抗の劣化傾向の把握が容易になる。 According to the first embodiment, when the insulation resistance RP of the P wire 15 or the insulation resistance RN of the N wire 16 is obtained, the E terminal 21 is grounded and the leakage flows from the DC power supply device 11 to the insulation resistance RP or the insulation resistance RN. Since the insulation resistance RP or the insulation resistance RN of the N wire 16 is obtained by measuring the current, the insulation resistance can be measured while using the electrical equipment, and all the combined insulation resistances of the DC circuit of the electrical equipment can be measured in a short time. be able to. Further, since there is no restriction on the measurement opportunity of the insulation resistance, it becomes easy to grasp the deterioration tendency of the insulation resistance by increasing the number of measurements.

そして、絶縁抵抗ＲＰまたは絶縁抵抗ＲＮの測定の際には直流地絡継電器１４をロックし、直流地絡継電器１４の分圧回路１７の分圧中点の接地点に漏洩電流が流れ込むのを防止するので、絶縁抵抗ＲＰまたは絶縁抵抗ＲＮに流れる漏洩電流の検出精度が向上する。また、検出回路ユニット２２に増幅器２４を接続して漏洩電流を増幅し、漏洩電流を検出する直流電流クランプメータとして高感度直流電流クランプメータ２５を使用するので、健全な絶縁抵抗ＲＰまたは絶縁抵抗ＲＮに流れる微少な漏洩電流であっても検出できる。 Then, when measuring the insulation resistance RP or the insulation resistance RN, the DC ground relay is locked to prevent the leakage current from flowing into the grounding point of the voltage dividing circuit 17 of the DC ground relay 14. Therefore, the detection accuracy of the leakage current flowing through the insulation resistance RP or the insulation resistance RN is improved. Further, since the high-sensitivity DC current clamp meter 25 is used as the DC current clamp meter for detecting the leakage current by connecting the amplifier 24 to the detection circuit unit 22 to amplify the leakage current, a sound insulation resistance RP or insulation resistance RN is used. Even a small leakage current flowing through can be detected.

さらには、高感度直流電流クランプメータ２５の後段にローパスフィルタ２６を接続するので、Ｐ電線またはＮ電線に流れる漏洩電流に重畳する商用電源の周波数成分を除去でき、絶縁抵抗に流れる漏洩電流の直流分成分だけを抽出できる。そして、検出したＰＮ電圧及びローパスフィルタで得られたＰ電線またはＮ電線に流れる電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めるので、測定精度の良い絶縁抵抗を得ることができる。 Furthermore, since the low-pass filter 26 is connected to the subsequent stage of the high-sensitivity DC current clamp meter 25, the frequency component of the commercial power supply superimposed on the leakage current flowing through the P wire or N wire can be removed, and the DC leakage current flowing through the insulation resistor can be removed. Only component components can be extracted. Then, since the combined insulation resistance of the plurality of DC power supply circuits is obtained based on the detected PN voltage and the current flowing through the P wire or the N wire obtained by the low-pass filter, it is possible to obtain an insulation resistance with good measurement accuracy.

次に、本発明の第２実施形態を説明する。図１０は本発明の第２実施形態に係る直流電源供給回路の絶縁抵抗測定方法の工程を示すフローチャートである。この第２実施形態は、図１に示した第１実施形態に対し、ステップＳ２に代えて、ステップＳ２Ａ、ステップＳ２Ｂを設けたものである。すなわち、直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定することに加え、Ｐ電線と大地との間のＰＥ電圧及びＮ電線と大地との間のＮＥ電圧を測定し（Ｓ２Ａ）、ＰＥ電圧及びＮＥ電圧に基づいて直流地絡継電器がロックされていることを確認する（Ｓ２Ｂ）ようにしたものである。図１と同一ステップには同一符号を付し重複する説明は省略する。 Next, a second embodiment of the present invention will be described. FIG. 10 is a flowchart showing the process of the insulation resistance measuring method of the DC power supply circuit according to the second embodiment of the present invention. In this second embodiment, step S2A and step S2B are provided in place of step S2 with respect to the first embodiment shown in FIG. That is, in addition to measuring the PN voltage between the positive P wire and the negative N wire connected to the DC power supply, the PE voltage between the P wire and the ground and between the N wire and the ground The NE voltage is measured (S2A), and it is confirmed that the DC ground relay is locked based on the PE voltage and the NE voltage (S2B). The same steps as those in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.

まず、図１に示した第１実施形態と同様に、直流地絡継電器をロックする（Ｓ１）。分圧回路１５の開閉スイッチ１８をオフし直流地絡継電器１４をロックするのは、分圧回路１５の接地点に漏洩電流が流れ込むのを防止し、絶縁抵抗ＲＰまたは絶縁抵抗ＮＰを測定するのに適した漏洩電流を得るためである。 First, the DC ground relay is locked in the same manner as in the first embodiment shown in FIG. 1 (S1). Turning off the open / close switch 18 of the voltage divider circuit 15 and locking the DC ground relay 14 prevents leakage current from flowing into the ground point of the voltage divider circuit 15 and measures the insulation resistance RP or insulation resistance NP. This is to obtain a leakage current suitable for the above.

次に、直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定すると共にＰ電線と大地との間のＰＥ電圧及び前記Ｎ電線と大地との間のＮＥ電圧を測定する（Ｓ２Ａ）。ＰＮ電圧の測定はＰ端子１９とＮ端子２０との間に電圧測定器を接続して測定する。ＰＥ電圧の測定はＰ端子１９とＥ端子２１との間に電圧測定器を接続して測定し、同様に、ＮＥ電圧の測定はＮ端子２０とＥ端子２１との間に電圧測定器を接続して測定する。 Next, the PN voltage between the positive P wire and the negative N wire connected to the DC power supply device is measured, the PE voltage between the P wire and the ground, and the NE between the N wire and the ground. Measure the voltage (S2A). The PN voltage is measured by connecting a voltage measuring device between the P terminal 19 and the N terminal 20. The PE voltage is measured by connecting a voltage measuring device between the P terminal 19 and the E terminal 21, and the NE voltage is measured by connecting the voltage measuring device between the N terminal 20 and the E terminal 21. And measure.

そして、ＰＥ電圧及びＮＥ電圧に基づいて直流地絡継電器がロックされていることを確認する（Ｓ２Ｂ）。図３において、直流地絡継電器１４がロックされていないとき（開閉スイッチ１８がオンのとき）は、前述したように、直流電源装置１１のＰＮ電圧は通常１１０Ｖであることから、ＰＥ電圧及びＮＥ電圧は５５Ｖで平衡する。これは、分圧回路１５の中点で抵抗分圧されその中点が接地された状態であるからである。一方、直流地絡継電器１４がロックされているとき（開閉スイッチ１８がオフのとき）は、ＰＥ電圧及びＮＥ電圧は５５Ｖから所定の時定数で０Ｖに変化する。これは、図３において、ＰＥ電圧及びＮＥ電圧の初期値は５５Ｖであるが、分圧回路１５の中点が開放された状態となったことに伴い、Ｐ電線１５の対地静電容量ＣＰまたはＮ電線１６の対地静電容量ＣＮにチャージされた電荷が放電されるからである。 Then, it is confirmed that the DC ground relay is locked based on the PE voltage and the NE voltage (S2B). In FIG. 3, when the DC ground relay relay 14 is not locked (when the open / close switch 18 is on), the PN voltage of the DC power supply device 11 is usually 110V as described above, so that the PE voltage and NE The voltage is balanced at 55V. This is because the resistance is divided at the midpoint of the voltage dividing circuit 15 and the midpoint is grounded. On the other hand, when the DC ground relay 14 is locked (when the open / close switch 18 is off), the PE voltage and NE voltage change from 55V to 0V with a predetermined time constant. This is because, in FIG. 3, the initial values of the PE voltage and the NE voltage are 55V, but as the middle point of the voltage dividing circuit 15 is opened, the capacitance CP of the P wire 15 to the ground or This is because the electric charge charged in the ground capacitance CN of the N electric wire 16 is discharged.

そこで、ＰＥ電圧及びＮＥ電圧は５５Vでほぼ平衡しているときは、直流地絡継電器１４はロックされていないと判断し、ＰＥ電圧及びＮＥ電圧が５５Vから０Ｖに減少しているときは、直流地絡継電器１４はロックされていると判断する。直流地絡継電器１４はロックされていないときは、ステップＳ１に戻り、直流地絡継電器１４をロックする。直流地絡継電器１４はロックされているときは、図１に示した第１実施形態と同様に、ステップＳ３〜ステップＳ７の処理を行う。 Therefore, when the PE voltage and NE voltage are almost balanced at 55V, it is determined that the DC ground relay relay 14 is not locked, and when the PE voltage and NE voltage are reduced from 55V to 0V, DC is determined. It is determined that the ground relay relay 14 is locked. When the DC ground relay is not locked, the process returns to step S1 to lock the DC ground relay 14. When the DC ground relay relay 14 is locked, the processes of steps S3 to S7 are performed in the same manner as in the first embodiment shown in FIG.

本発明の第２実施形態によれば、実施形態１の効果に加え、ＰＥ電圧及びＮＥ電圧に基づいて直流地絡継電器１４がロックされていることを確認するので、直流地絡継電器１４の分圧回路の分圧中点に漏洩電流が流れ込む状態で絶縁抵抗の測定を行うことがなくなる。従って、絶縁抵抗の測定精度が高まる。 According to the second embodiment of the present invention, in addition to the effect of the first embodiment, it is confirmed that the DC ground relay 14 is locked based on the PE voltage and the NE voltage, so that the DC ground relay 14 is divided. It is no longer necessary to measure the insulation resistance when the leakage current flows into the voltage dividing midpoint of the voltage circuit. Therefore, the measurement accuracy of the insulation resistance is improved.

以上、本発明のいくつかの実施形態を説明したが、これらの実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。これら新規な実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。これら実施形態やその変形は、発明の範囲や要旨に含まれるとともに、特許請求の範囲に記載された発明とその均等の範囲に含まれる。 Although some embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

１１…直流電源装置、１２…直流母線、１３…直流電源供給回路、１４…直流地絡継電器、１５…Ｐ電線、１６…Ｎ電線、１７…分圧回路、１８…開閉スイッチ、１９…Ｐ端子、２０…Ｎ端子、２１…Ｅ端子、２２…検出回路ユニット、２３…切換スイッチ、２４…増幅器、２５…高感度直流電流クランプメータ、２６…ローパスフィルタ、２７…電流測定器 11 ... DC power supply, 12 ... DC bus, 13 ... DC power supply circuit, 14 ... DC ground fault relay, 15 ... P wire, 16 ... N wire, 17 ... Voltage divider circuit, 18 ... Open / close switch, 19 ... P terminal , 20 ... N terminal, 21 ... E terminal, 22 ... Detection circuit unit, 23 ... Changeover switch, 24 ... Amplifier, 25 ... High-sensitivity DC current clamp meter, 26 ... Low-pass filter, 27 ... Current measuring instrument

Claims (2)

電気所の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する複数の直流電源供給回路のいずれかに地絡故障が発生したとき動作する直流地絡継電器をロックし、
前記直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定し、
前記Ｐ電線または前記Ｎ電線への接続を切り換えて前記Ｐ電線または前記Ｎ電線のいずれかを接地し前記Ｐ電線または前記Ｎ電線に流れる電流を検出する検出回路ユニットを前記Ｐ電線と前記Ｎ電線との間に接続し、
前記検出回路ユニットに増幅器及び高感度直流電流クランプメータを接続すると共に高感度直流電流クランプメータにローパスフィルタを接続し、
前記高感度直流クランプメータのゼロ点調整を行い前記Ｐ電線または前記Ｎ電線のうち絶縁抵抗を測定する側の反対側の電線を前記検出回路ユニットにより接地し、
前記増幅器で増幅され前記高感度直流クランプメータで検出された前記Ｐ電線または前記Ｎ電線に流れる電流から前記ローパスフィルタで商用電源の周波数成分を除去した前記Ｐ電線または前記Ｎ電線に流れる直流分電流を測定し、
前記ＰＮ電圧及び前記ローパスフィルタで得られた前記Ｐ電線または前記Ｎ電線に流れる直流分電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めることを特徴とする直流電源供給回路の絶縁抵抗測定方法。 A DC ground relay that operates when a ground fault occurs in any of the multiple DC power supply circuits that supply DC power from the DC power supply to the control circuit for operating the electrical equipment of the electric station via the DC bus. Lock and
The PN voltage between the positive electrode P wire and the negative electrode N wire connected to the DC power supply device is measured.
A detection circuit unit that switches the connection to the P wire or the N wire to ground either the P wire or the N wire and detects a current flowing through the P wire or the N wire is the P wire and the N wire. Connect with and
An amplifier and a high-sensitivity DC current clamp meter are connected to the detection circuit unit, and a low-pass filter is connected to the high-sensitivity DC current clamp meter.
The zero point of the high-sensitivity DC clamp meter is adjusted, and the wire on the opposite side of the P wire or the N wire on the side where the insulation resistance is measured is grounded by the detection circuit unit.
The DC component current flowing through the P wire or the N wire obtained by removing the frequency component of the commercial power supply from the current flowing through the P wire or the N wire detected by the high-sensitivity DC clamp meter amplified by the amplifier. Measure and
The insulation resistance of a DC power supply circuit, which is characterized by obtaining the combined insulation resistance of a plurality of DC power supply circuits based on the PN voltage and the DC component current flowing through the P wire or the N wire obtained by the low pass filter. Measuring method. 電気所の電気設備を操作するための制御回路に直流電源装置から直流母線を介して直流電源を供給する複数の直流電源供給回路のいずれかに地絡故障が発生したとき動作する直流地絡継電器をロックし、
前記直流電源装置に接続される正極のＰ電線と負極のＮ電線との間のＰＮ電圧を測定すると共に前記Ｐ電線と大地との間のＰＥ電圧及び前記Ｎ電線と大地との間のＮＥ電圧を測定し、
前記ＰＥ電圧及び前記ＮＥ電圧に基づいて前記直流地絡継電器がロックされていることを確認し、
前記Ｐ電線または前記Ｎ電線への接続を切り換えて前記Ｐ電線または前記Ｎ電線のいずれかを接地し前記Ｐ電線または前記Ｎ電線に流れる電流を検出する検出回路ユニットを前記Ｐ電線と前記Ｎ電線との間に接続し、
前記検出回路ユニットに増幅器及び高感度直流電流クランプメータを接続すると共に高感度直流電流クランプメータにローパスフィルタを接続し、
前記高感度直流クランプメータのゼロ点調整を行い前記Ｐ電線または前記Ｎ電線のうち絶縁抵抗を測定する側の反対側の電線を前記検出回路ユニットにより接地し、
前記増幅器で増幅され前記高感度直流クランプメータで検出された前記Ｐ電線または前記Ｎ電線に流れる電流から前記ローパスフィルタで商用電源の周波数成分を除去した前記Ｐ電線または前記Ｎ電線に流れる直流分電流を測定し、
前記ＰＮ電圧及び前記ローパスフィルタで得られた前記Ｐ電線または前記Ｎ電線に流れる直流分電流に基づいて複数の直流電源供給回路の合成絶縁抵抗を求めることを特徴とする直流電源供給回路の絶縁抵抗測定方法。 A DC ground relay that operates when a ground fault occurs in any of the multiple DC power supply circuits that supply DC power from the DC power supply to the control circuit for operating the electrical equipment of the electric station via the DC bus. Lock and
The PN voltage between the positive electrode P wire and the negative electrode N wire connected to the DC power supply device is measured, and the PE voltage between the P wire and the ground and the NE voltage between the N wire and the ground are measured. Measure and
Confirm that the DC ground relay is locked based on the PE voltage and the NE voltage, and confirm that the DC ground relay is locked.
A detection circuit unit that switches the connection to the P wire or the N wire to ground either the P wire or the N wire and detects a current flowing through the P wire or the N wire is the P wire and the N wire. Connect with and
An amplifier and a high-sensitivity DC current clamp meter are connected to the detection circuit unit, and a low-pass filter is connected to the high-sensitivity DC current clamp meter.
The zero point of the high-sensitivity DC clamp meter is adjusted, and the wire on the opposite side of the P wire or the N wire on the side where the insulation resistance is measured is grounded by the detection circuit unit.
The DC component current flowing through the P wire or the N wire obtained by removing the frequency component of the commercial power supply from the current flowing through the P wire or the N wire detected by the high-sensitivity DC clamp meter amplified by the amplifier. Measure and
The insulation resistance of a DC power supply circuit, which is characterized by obtaining the combined insulation resistance of a plurality of DC power supply circuits based on the PN voltage and the DC component current flowing through the P wire or the N wire obtained by the low pass filter. Measuring method.

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