JP5514842B2 - Insulation monitoring device and monitoring method for DC ungrounded circuit - Google Patents

Insulation monitoring device and monitoring method for DC ungrounded circuit Download PDF

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JP5514842B2
JP5514842B2 JP2012007602A JP2012007602A JP5514842B2 JP 5514842 B2 JP5514842 B2 JP 5514842B2 JP 2012007602 A JP2012007602 A JP 2012007602A JP 2012007602 A JP2012007602 A JP 2012007602A JP 5514842 B2 JP5514842 B2 JP 5514842B2
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一朗 玉井
拓朗 風間
純也 中村
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光商工株式会社
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Description

本発明は、直流非接地電路における電路と大地間の絶縁を監視する技術に関し、特に、地絡継電器が動作する以前の絶縁状態を監視する技術に関する。   The present invention relates to a technique for monitoring insulation between an electric circuit and a ground in a direct current ungrounded electric circuit, and more particularly to a technique for monitoring an insulation state before a ground fault relay operates.

近年、CO2を排出しない発電、また原子力発電の事故などで、自然エネルギーの利用が見直され、自然エネルギーを利用した発電の開発が進められている。太陽光を利用した太陽光発電、風力や地熱を利用した発電、その他、化学反応を利用した燃料電池等々である。これらで発電された電力はすべて直流電力で一般に利用する場合はインバータ等で交流電力に変換して利用される。 In recent years, the use of natural energy has been reconsidered due to power generation that does not emit CO 2 or accidents in nuclear power generation, and development of power generation using natural energy has been promoted. Solar power generation using sunlight, power generation using wind power and geothermal heat, and other fuel cells using chemical reactions. When all of the electric power generated by these is generally used as DC power, it is converted into AC power by an inverter or the like.

大規模発電システム、例えばメガソーラーのように大規模太陽光発電所の建設は、多大な設置面積を要し都市から離れた場所に設置され、そこから直流電路によって離れた場所の変電所に送電される場合が多い。   Construction of a large-scale power generation system, such as a mega solar power plant, requires a large installation area and is installed in a place away from the city, and is then transmitted to a substation away from the city by a DC circuit. Often done.

直流送電においても交流送電と同様に、送電路と大地間の絶縁抵抗が劣化して地絡事故を起こす場合があるので直流地絡継電器が設置されている。地絡継電器が作動すると電路が遮断され需要者側に多大な損害を与える。   In direct current power transmission, as in the case of alternating current power transmission, the insulation resistance between the transmission line and the ground may deteriorate, and a ground fault may occur, so a direct current ground fault relay is installed. When the ground fault relay operates, the electric circuit is cut off, causing a great deal of damage to the consumer.

本発明は、この地絡継電器が作動するに到る前に直流電路と大地間の絶縁抵抗の変化を常時監視し、遮断器が遮断する以前に事前の策を講じられる様にする事を目的とするものである。   The purpose of the present invention is to constantly monitor the change in insulation resistance between the DC circuit and the ground before this ground fault relay is activated, and to take precautions before the circuit breaker is shut off. It is what.

従来、この種の絶縁監視方法として図5に示すものが知られている。図5は従来の絶縁監視方法の等価回路図で、同図において、10は直流電源、11,12は直流電源10からの電力を送電する正極側電路(以下、正極電路と略称)と負極側電路(以下、負極電路と略称)、R1、R3は電路間電圧を分圧する分圧用抵抗体、R2、R4は正極電路11と大地E間及び負極電路12と大地E間に生じる正極側及び負極側絶縁抵抗、R5は分圧点E´と大地E間に設けられた検出用抵抗体を示し、正極電路又は負極電路と大地間の絶縁抵抗が変化すると、分圧用抵抗低体R1、R3と絶縁抵抗R2、R4の比率により、検出抵抗体R5に相互に流れ込む電流が変化するため、この電流の変化量を検出するようにしている(例えば、特許文献1)。   Conventionally, an insulation monitoring method of this type is shown in FIG. FIG. 5 is an equivalent circuit diagram of a conventional insulation monitoring method. In the figure, 10 is a DC power source, 11 and 12 are a positive-side electric circuit (hereinafter abbreviated as a positive-electrode circuit) and a negative-electrode side for transmitting power from the DC power source 10. An electric circuit (hereinafter abbreviated as a negative circuit), R1 and R3 are voltage dividing resistors that divide the voltage between the electric circuits, and R2 and R4 are a positive electrode and a negative electrode that are generated between the positive electrode 11 and the ground E and between the negative electrode 12 and the ground E. A side insulation resistance, R5, indicates a detection resistor provided between the voltage dividing point E ′ and the ground E. When the insulation resistance between the positive electrode circuit or the negative electrode circuit and the ground changes, the voltage dividing resistance low bodies R1, R3 and Since the current flowing into the detection resistor R5 changes depending on the ratio of the insulation resistances R2 and R4, the amount of change in the current is detected (for example, Patent Document 1).

特開2004−271285号公報。Japanese Patent Application Laid-Open No. 2004-271285.

図5に示した従来の方法では、検出用抵抗体に流れる電流の変化量が分かるだけで絶縁抵抗値を求めることは出来ない。また、絶縁抵抗が変化して検出用抵抗体に流れる込む電流の正極側絶縁抵抗R2と負極側絶縁抵抗R4の比率と、分圧用抵抗体R1とR3の抵抗比率が同じとなると、検出用抵抗体R5に流れる電流I5は零となる。即ち、大地Eと分圧点E´の電位が同電位となり、検出用抵抗体R5に電圧が発生せず絶縁抵抗の検出が出来ない。   In the conventional method shown in FIG. 5, the insulation resistance value cannot be obtained only by knowing the amount of change in the current flowing through the detection resistor. Further, when the ratio of the positive-side insulation resistance R2 and the negative-side insulation resistance R4 of the current flowing into the detection resistor due to the change in the insulation resistance and the resistance ratio of the voltage dividing resistors R1 and R3 are the same, the detection resistor The current I5 flowing through the body R5 is zero. That is, the potentials of the ground E and the voltage dividing point E ′ are the same, and no voltage is generated in the detection resistor R5, so that the insulation resistance cannot be detected.

また、正極側と負極側の絶縁抵抗R2とR4同時に劣化した場合には、R2−R5−R3に流れる電流Igpと、R1―R5―R4に流れる電流Ignが相互に作用し、劣化した絶縁抵抗R2、R4に流れる電流を検出用抵抗体R5で正確に検出できない。従って、正確な絶縁抵抗値の検出は出来ない、という課題がある。   Further, when the insulation resistances R2 and R4 on the positive electrode side and the negative electrode side deteriorate at the same time, the current Igp flowing in R2-R5-R3 and the current Ign flowing in R1-R5-R4 interact with each other, and the deteriorated insulation resistance The current flowing through R2 and R4 cannot be accurately detected by the detection resistor R5. Therefore, there is a problem that an accurate insulation resistance value cannot be detected.

本発明はこのような課題を解決するために成されたもので、計測時に分圧用抵抗体の分圧比を強制的に変え、上記の従来検出出来なかった条件のときでも絶縁抵抗値を正確に検出出来るようにするものである。   The present invention has been made to solve such a problem, and forcibly changing the voltage dividing ratio of the voltage dividing resistor during measurement, so that the insulation resistance value can be accurately determined even under the above-mentioned conditions that could not be detected conventionally. It makes it possible to detect.

本発明において、上記の課題を解決するための手段は、直流非接地式電路の電路電圧を検出する電路電圧検出手段と、この電路電圧を分圧する分圧用抵抗体R1、R3と、この分圧用抵抗体の分圧比を補助抵抗体を正極側と負極側に交互に切り替えて分圧比を変更する切替手段と、該切替手段と大地E間に設けられ大地間に流れる電流を検出して電路と大地間の電流を検出する電流検出手段と、該電流検出手段で検出した検出信号と前記の電路電圧検出手段で検出した電圧信号を入力し正極側に切替えたときの電路と大地間の電流信号と負極側に切替えたときの電路と大地間の電流信号から絶縁抵抗を演算する演算手段と、該演算手段で演算した絶縁抵抗値を表示する計測表示手段及び又は警報手段を備え、正極側絶縁抵抗をR2、負極側絶縁抵抗をR4としたときのR2とR4の絶縁抵抗値の算出は次の演算式で求めて直流非接地式電路と大地間の絶縁抵抗値の変化を監視するようにする。   In the present invention, means for solving the above-mentioned problems are circuit voltage detecting means for detecting the circuit voltage of the DC non-grounded circuit, voltage dividing resistors R1 and R3 for dividing the circuit voltage, and voltage dividing A switching means for changing the voltage dividing ratio by alternately switching the auxiliary resistor between the positive electrode side and the negative electrode side, and a current provided between the switching means and the ground E to detect a current flowing between the ground and the electric circuit; Current detection means for detecting a current between the earth, a detection signal detected by the current detection means and a voltage signal detected by the electric circuit voltage detection means, and a current signal between the electric circuit and the earth when switched to the positive side And a calculation means for calculating an insulation resistance from a current signal between the electric circuit and the ground when switched to the negative electrode side, and a measurement display means and / or an alarm means for displaying the insulation resistance value calculated by the calculation means. Resistance R2, negative side Calculating the insulation resistance values of R2 and R4 when the resistance was and R4 so as to monitor changes in insulation resistance value between the DC Nonreferenced path and ground and calculated by the following arithmetic expression.

R2=(V4a−V4b)×V/(V4b×I5a−V4a×I5b)
R4=(V2b−V2a)×V/(V2b×I5a−V2a×I5b)
但し、Vは電路電圧、R1、R3は分圧用抵抗体、R6は補助分圧抵抗体、R5は電流検出手段に
有する検出用抵抗体でこれらの値は既知。V2、V4は電圧で、これに付されている数字の抵
抗体の電圧、Iは電流を示しこれに付されている数字の抵抗に流れる電流。a,bは切替
手段での切り替えオン接点を示す。
R2 = (V4a−V4b) × V / (V4b × I5a−V4a × I5b)
R4 = (V2b−V2a) × V / (V2b × I5a−V2a × I5b)
However, V is a circuit voltage, R1 and R3 are voltage dividing resistors, R6 is an auxiliary voltage dividing resistor, and R5 is a detection resistor included in the current detection means, and these values are known. V2 and V4 are voltages, the voltage of the numerical resistor attached thereto, and I is the current flowing through the numerical resistor attached thereto. a and b indicate switching-on contacts in the switching means.

なお、V4aは、V3a−V5a、V4bは、V3b−V5b、V2aは、V1a+V5a、V2bは、V1b+V5bで求めることが出来る。   V4a can be obtained by V3a-V5a, V4b can be obtained by V3b-V5b, V2a can be obtained by V1a + V5a, and V2b can be obtained by V1b + V5b.

また、監視方法は、直流非接地式電路の電圧を分圧用抵抗体で分圧し、分圧用抵抗体の分圧点と大地間に分圧比を切り替え変更する切替手段を設け、この切替手段と大地間に分圧点と大地間に流れる電流を検出する検出手段を設けるとともに、切替手段は正極側と負極側の分圧用抵抗体に補助分圧抵抗体を交互に接続して分圧比を変更し、夫々変更したときに流れる電流を電流検出手段で検出し、この検出した夫々の電流と電路電圧から演算手段によって正極電路と大地間、負極電路と大地間の絶縁抵抗値を算出し、算出した値を基に可視可能に表示する計測表示手段及び又は絶縁抵抗値が所定値以下になったときに警報を出すようにして直流非接地式電路と大地間の絶縁抵抗を監視する。   In addition, the monitoring method includes a switching unit that divides the voltage of the DC ungrounded circuit with a voltage dividing resistor, and switches and changes the voltage dividing ratio between the voltage dividing point of the voltage dividing resistor and the ground. In addition to providing a detecting means for detecting the current flowing between the voltage dividing point and the ground, the switching means alters the voltage dividing ratio by alternately connecting auxiliary voltage dividing resistors to the voltage dividing resistors on the positive electrode side and the negative electrode side. The current flowing when the current is changed is detected by the current detection means, and the insulation resistance values between the positive circuit and the ground and the negative circuit and the ground are calculated by the calculation means from the detected current and the circuit voltage. The measurement display means for displaying the value based on the value and / or the insulation resistance between the DC non-grounded electric circuit and the ground is monitored so that an alarm is issued when the insulation resistance value becomes a predetermined value or less.

上記の絶縁抵抗値の演算は、正極電路と大地間の絶縁抵抗をR2、負極電路と大地間の絶縁抵抗をR4としたとき次の演算式で求めることできる。   The above-described calculation of the insulation resistance value can be obtained by the following arithmetic expression when the insulation resistance between the positive electrode circuit and the ground is R2 and the insulation resistance between the negative electrode circuit and the ground is R4.

R2=(V4a−V4b)×V/(V4b×I5a−V4a×I5b)
R4=(V2b−V2a)×V/(V2b×I5a−V2a×I5b)
但し、Vは電路電圧、R1、R3は分圧用抵抗体、R6は補助分圧抵抗体、R5は電流検出手
段に有する検出用抵抗体でこれらの値は既知。V2、V4は電圧で、これに付されている数字
の抵抗体の電圧、Iは電流を示しこれに付されている数字の抵抗に流れる電流。a,bは
切替手段での切り替えオン接点を示す。
R2 = (V4a−V4b) × V / (V4b × I5a−V4a × I5b)
R4 = (V2b-V2a) x V / (V2b x I5a-V2a x I5b)
However, V is a circuit voltage, R1 and R3 are voltage dividing resistors, R6 is an auxiliary voltage dividing resistor, and R5 is a detection resistor included in the current detection means, and these values are known. V2 and V4 are voltages, the voltage of the numerical resistor attached thereto, and I is the current flowing through the numerical resistor attached thereto. a and b indicate switching-on contacts in the switching means.

なお、V4aは、V3a−V5a、V4bは、V3b−V5b、V2aは、V1a+V5a、V2bは、V1b+V5bで求めることが出来る。   V4a can be obtained by V3a-V5a, V4b can be obtained by V3b-V5b, V2a can be obtained by V1a + V5a, and V2b can be obtained by V1b + V5b.

(1) 従来の方法では、正極側絶縁抵抗R2と負極側絶縁抵抗R4が同じ値、或いは分圧用抵抗体R1とR3と同じ比率になると電位が同電位となり計測する抵抗電圧が発生せず、絶縁抵抗を計測できなかったが、本発明では分圧用抵抗体の値を分圧比の切替手段で切替えることにより絶縁抵抗側と分圧用抵抗側に電位差が発生し、従来出来なかった条件のときでも絶縁抵抗値を検出することが出来る。   (1) In the conventional method, when the positive-side insulation resistance R2 and the negative-side insulation resistance R4 have the same value or the same ratio as the voltage dividing resistors R1 and R3, the potential becomes the same potential and no resistance voltage to be measured is generated. Although the insulation resistance could not be measured, in the present invention, by switching the value of the voltage dividing resistor using the voltage dividing ratio switching means, a potential difference occurs between the insulation resistance side and the voltage dividing resistance side, even under conditions that could not be achieved in the past. The insulation resistance value can be detected.

(2)、分圧比切替手段でオン、オフを交互に切替えることにより、正極側と負極側の各絶縁抵抗を求めることが出来る。   (2) The insulation resistances on the positive electrode side and the negative electrode side can be obtained by alternately switching on and off by the voltage division ratio switching means.

(3) 電路電圧を常時検出することで、電路電圧が変動する場合でも正確な絶縁抵抗値を求めることが出来る。   (3) By always detecting the circuit voltage, an accurate insulation resistance value can be obtained even when the circuit voltage fluctuates.

(4) 分圧比変更用に補助抵抗体を用いた場合の補助分圧抵抗体R6の抵抗値をR1>>R6およびR3>>R6とすることにより、電路と大地間の電圧変動を小さく抑えることが出来、負荷機器へのノイズの影響を小さく出来る。   (4) By setting the resistance value of the auxiliary voltage dividing resistor R6 when the auxiliary resistor is used for changing the voltage dividing ratio to R1 >> R6 and R3 >> R6, voltage fluctuation between the electric circuit and the ground is suppressed to be small. And the influence of noise on the load equipment can be reduced.

本発明の実施の形態の構成図。The block diagram of embodiment of this invention. 図1の等価回路図。The equivalent circuit diagram of FIG. 図2におけるa側接点オン、b側接点オフ時の等価回路図。FIG. 3 is an equivalent circuit diagram when the a-side contact is on and the b-side contact is off in FIG. 2. 図2におけるb側接点オン、a側接点オフ時の等価回路図。FIG. 3 is an equivalent circuit diagram when the b-side contact is on and the a-side contact is off in FIG. 2. 従来技術の説明図。Explanatory drawing of a prior art.

以下、本発明の実施の形態を図面によって説明する。図1は本発明を説明するための構成図で、1は直流電源、2,3は直流電源1に接続されている正極及び負極側の正極電路及び負極電路、4は絶縁監視装置を示す。該絶縁監視装置4は、電路電圧Vを取り込み電路電圧を検出する電路電圧検出手段41、この電路電圧を分圧する分圧用抵抗体R1、R3及びこの分圧用抵抗体R1とR3の分圧比を補助分圧抵抗体R6を切り替えて変更する分圧比の切替手段42を有する。   Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram for explaining the present invention, wherein 1 is a DC power source, 2 and 3 are positive and negative side positive and negative electrode circuits connected to the DC power source 1, and 4 is an insulation monitoring device. The insulation monitoring device 4 assists the circuit voltage detection means 41 that takes in the circuit voltage V and detects the circuit voltage, the voltage dividing resistors R1 and R3 that divide the circuit voltage, and the voltage dividing ratio of the voltage dividing resistors R1 and R3. A voltage dividing ratio switching means 42 for switching and changing the voltage dividing resistor R6 is provided.

43は検出抵抗体からなる電流検出手段で、分圧比の切替手段42と大地E間に接地線44を介して接続され、分圧用抵抗体から大地E間に流れる電流を検出する。45は電流検出手段43の検出信号を増幅する増幅回路、46はこの増幅回路45の出力信号と電路電圧検出手段41で検出した電路電圧信号を入力し、これら入力信号をA/D変換器46でデジタル信号に変換して演算手段47に入力する。   Reference numeral 43 denotes current detection means comprising a detection resistor, which is connected between the voltage dividing ratio switching means 42 and the ground E via a ground line 44 and detects a current flowing between the voltage dividing resistor and the ground E. 45 is an amplifier circuit for amplifying the detection signal of the current detection means 43, 46 is inputted with the output signal of the amplification circuit 45 and the circuit voltage signal detected by the circuit voltage detection means 41, and these input signals are converted into an A / D converter 46. The digital signal is converted into a digital signal and input to the calculation means 47.

48は分圧比の切替手段42の切替制御手段で、演算手段47からの指令により分圧比の切替手段42内の接点を切替える。この切替えは、正極電路2側の分圧用抵抗体R1に接続される接点をa側接点、負極電路3側の分圧用抵抗体R3に接続される接点をb側接点とし、一方がオンのとき他方がオフとなり所定の時間間隔で交互にオン、オフ制御される。R6は補助分圧抵抗体で、a側接点がオンのとき分圧抵抗体R3側に直列に挿入され、分圧比はR1/(R3+R6)となり分圧比が変更される。b側接点オンのときも同様に変更される。   48 is a switching control means of the voltage dividing ratio switching means 42, and switches the contacts in the voltage dividing ratio switching means 42 according to a command from the calculating means 47. This switching is performed when the contact connected to the voltage dividing resistor R1 on the positive electrode circuit 2 side is the a side contact, the contact connected to the voltage dividing resistor R3 on the negative electrode circuit 3 side is the b side contact, and one is on The other is turned off and is alternately turned on and off at predetermined time intervals. R6 is an auxiliary voltage dividing resistor, which is inserted in series on the voltage dividing resistor R3 side when the a-side contact is on, and the voltage dividing ratio becomes R1 / (R3 + R6), and the voltage dividing ratio is changed. The same applies when the b-side contact is on.

R2は本発明が検出監視しようとする正極電路と大地間の正極側絶縁抵抗、R4は負極電路と大地間の負極側絶縁抵抗である。この正極側、負極側絶縁抵抗R2及びR4は電路正常の状態では無限大に近く、電路と大地間の絶縁が劣化することにより現れ変化する。   R2 is a positive electrode side insulation resistance between the positive electrode circuit and the ground to be detected and monitored by the present invention, and R4 is a negative electrode side insulation resistance between the negative electrode circuit and the ground. The positive-side and negative-side insulation resistances R2 and R4 are close to infinity in the normal state of the electric circuit, and appear and change due to deterioration of the insulation between the electric circuit and the ground.

今、正極電路2と大地間の絶縁が劣化し、正極側絶縁抵抗R2が発生すると、分圧比の切替手段42の接点がa側オン、b側オフの状態のときは、分圧用抵抗体R3に補助分圧抵抗体R6が加わり、分圧比はR1/(R3+R6)となり、分圧された電流は電流検出手段43から大地Eに流れる。b側オン、a側オフのときは、分圧比は(R1+R6)/R3となり、分圧された電流による電流検出手段43から大地Eに流れる。   Now, when the insulation between the positive electrode circuit 2 and the ground deteriorates and the positive electrode side insulation resistance R2 is generated, the voltage dividing resistor R3 when the contact of the voltage dividing ratio switching means 42 is in the a side on and the b side off. Is added to the auxiliary voltage dividing resistor R6, the voltage dividing ratio becomes R1 / (R3 + R6), and the divided current flows from the current detecting means 43 to the ground E. When the b-side is on and the a-side is off, the voltage division ratio is (R1 + R6) / R3, and flows from the current detection means 43 to the ground E by the divided current.

電流検出手段43は切替手段42で分圧比を切り替えたときに流れる電流を夫々検出した検出信号を、増幅回路45、A/D変換器46を介して演算手段47に入力する。演算手段47は夫々の入力信号と電路電圧検出手段41からの電圧信号を基に正極側、負極側絶縁抵抗R2、R4を算出する。48は分圧比の切替手段42の切替接点を制御する切替制御手段で、所定の時間間隔で接点を交互に切り替える。49は計測表示手段で、演算手段47で演算した結果を可視可能な状態で数字やグラフ等で表示する。50は警報手段で、絶縁抵抗値があらかじめ設定した値以下となったとき音又は光によって警報する。   The current detection means 43 inputs detection signals, each of which detects the current that flows when the voltage dividing ratio is switched by the switching means 42, to the calculation means 47 via the amplifier circuit 45 and the A / D converter 46. The calculation means 47 calculates the positive and negative side insulation resistances R2 and R4 based on the respective input signals and the voltage signal from the circuit voltage detection means 41. 48 is a switching control means for controlling the switching contact of the voltage dividing ratio switching means 42, and switches the contacts alternately at predetermined time intervals. 49 is a measurement display means, and displays the result calculated by the calculation means 47 in a visible state as a number or a graph. Reference numeral 50 denotes an alarm means that issues an alarm by sound or light when the insulation resistance value falls below a preset value.

図2は演算手段47による演算を説明するための等価回路図を示す。なお、同図において図1と同じ又は相当部分には同じ符号を付して説明を省略する。また、図3は図2における分圧比の切替手段42のa側接点オン、b側接点オフの場合、図4はa側接点オフ、b側接点オンの場合の等価回路を示し、これらの等価回路によって絶縁抵抗R2とR4の抵抗値の算出について説明する。   FIG. 2 shows an equivalent circuit diagram for explaining the calculation by the calculation means 47. In the figure, the same or corresponding parts as those in FIG. 3 shows an equivalent circuit when the a-side contact is on and the b-side contact is off, and FIG. 4 shows an equivalent circuit when the a-side contact is off and the b-side contact is on. Calculation of the resistance values of the insulation resistances R2 and R4 by the circuit will be described.

なお、次の式中、記号のa、bの符号は、a側接点及びb側接点が夫々オンの状態を示し、I1〜I5及びV1〜V5は夫々分圧用抵抗体、検出用抵抗体、絶縁抵抗R1〜R5に流れる電流およびその抵抗間の電圧を示し、R5は電流検出手段43内に有する検出用抵抗体を示し、また、R3aは、R3+R6、R1bは、R1+R6を示している。   In the following formulas, the symbols a and b indicate that the a-side contact and the b-side contact are on, respectively, and I1 to I5 and V1 to V5 are voltage dividing resistors, detection resistors, The current flowing through the insulation resistances R1 to R5 and the voltage between the resistances are shown. R5 shows a detection resistor in the current detection means 43. R3a shows R3 + R6, and R1b shows R1 + R6.

正極側絶縁抵抗R2、負極側絶縁抵抗R4は以下のように求める。   The positive electrode side insulation resistance R2 and the negative electrode side insulation resistance R4 are obtained as follows.

<a側接点オン、b側接点オフのとき>
最初に電路電圧Vと検出用抵抗体R5の電圧V5aを計測する。このV5aからそこに流れる電流I5aをV5a/R5で求める。
<When a side contact is on, b side contact is off>
First, the circuit voltage V and the voltage V5a of the detection resistor R5 are measured. The current I5a flowing therethrough from V5a is obtained by V5a / R5.

次に、抵抗R1に流れる電流I1aを求める。
I1a=(V+R3a×I5a)/(R1+R3a)・・・・(1)
そして、抵抗R1の電圧V1aは、V1a=I1a×R1で求める。
Next, the current I1a flowing through the resistor R1 is obtained.
I1a = (V + R3a × I5a) / (R1 + R3a) (1)
The voltage V1a of the resistor R1 is obtained by V1a = I1a × R1.

次に、抵抗R3aに流れる電流I3aは、I3a=I1a−I5aで求まり、その電圧V3aはI3a×R3aで求まる。   Next, the current I3a flowing through the resistor R3a is obtained by I3a = I1a−I5a, and the voltage V3a is obtained by I3a × R3a.

次に、抵抗R2の電圧V2aは、V2a=V1a+V5aで求め、抵抗R4の電圧V4aは、V3a−V5aで求まる。   Next, the voltage V2a of the resistor R2 is obtained by V2a = V1a + V5a, and the voltage V4a of the resistor R4 is obtained by V3a−V5a.

抵抗R2に流れる電流I2aは、
I2a=(V−R4×I5a)/(R2+R4)=V2a/R2・・・・・(2)
この式より、R2=V2a×(R2+R4)/(V−R4×I5a)・・・・(3)。
The current I2a flowing through the resistor R2 is
I2a = (V−R4 × I5a) / (R2 + R4) = V2a / R2 (2)
From this equation, R2 = V2a * (R2 + R4) / (V-R4 * I5a) (3).

<b側接点オン、a側接点オフのとき>
最初に電路電圧Vと検出用抵抗R5の電圧V5bを計測する。このV5bからI5bをV5b/R5で求める。
<When b side contact is on, a side contact is off>
First, the circuit voltage V and the voltage V5b of the detection resistor R5 are measured. From this V5b, I5b is obtained by V5b / R5.

次に、抵抗R1bに流れる電流I1bを求める。
I1b=(V+R3×I5b)/(R1b+R3)・・・・(4)
そして、抵抗R1bの電圧V1bは、V1b=I1b×R1bで求める。
Next, the current I1b flowing through the resistor R1b is obtained.
I1b = (V + R3 × I5b) / (R1b + R3) (4)
The voltage V1b of the resistor R1b is obtained by V1b = I1b × R1b.

次に、抵抗R3に流れる電流I3bは、I3b=I1b−I5bで求まり、その電圧V3bはI3b×R3で求まる。   Next, the current I3b flowing through the resistor R3 is obtained by I3b = I1b−I5b, and the voltage V3b is obtained by I3b × R3.

次に、抵抗R2の電圧V2bは、V2b=V1b+V5bで求め、抵抗R4の電圧V4bは、V3b−V5bで求まる。   Next, the voltage V2b of the resistor R2 is obtained by V2b = V1b + V5b, and the voltage V4b of the resistor R4 is obtained by V3b−V5b.

抵抗R2に流れる電流I2bは、
I2b=(V−R4×I5b)/(R2+R4)=V2b/R2・・・・・(5)
この式より、R2=V2b×(R2+R4)/(V−R4×I5b)・・・・(6)
式(3)と(6)の両計算結果から、
V2a×(R2+R4)/(V−R4×I5a)=V2b×(R2+R4)/(V−R4×I5b)・・・・(7)
が成り立ち、これから負極側絶縁抵抗R4は、
R4=(V2b−V2a)×V/(V2b×I5a−V2a×I5b)・・・・・(8)
が求まる。
The current I2b flowing through the resistor R2 is
I2b = (V−R4 × I5b) / (R2 + R4) = V2b / R2 (5)
From this equation, R2 = V2b × (R2 + R4) / (V−R4 × I5b) (6)
From the calculation results of both equations (3) and (6),
V2a * (R2 + R4) / (V-R4 * I5a) = V2b * (R2 + R4) / (V-R4 * I5b) (7)
From this, the negative side insulation resistance R4 is
R4 = (V2b−V2a) × V / (V2b × I5a−V2a × I5b) (8)
Is obtained.

同様に、I4a=(V+R2×I5a)/(R2+R4)=V4a/R4・・・(9)
R4=V4a×(R2+R4)/(V+R4×I5a)・・・・・・・・・・・(10)
同様に、I4b=(V+R2×I5b)/(R2+R4)=V4b/R4・・・(11)
R4=V4b×(R2+R4)/(V+R4×I5b)・・・・・・・・・・(12)
式(10)、(12)の両計算結果から
V4a×(R2+R4)/(V+R2×I5a)=V4b×(R2+R4)/(V+R2×I5b)
が成り立ち、これから正極側絶縁抵抗R2は、
R2=(V4a−V4b)×V/(V4b×I5a−V4a×I5b)・・・・(13)
が求まる。
Similarly, I4a = (V + R2 × I5a) / (R2 + R4) = V4a / R4 (9)
R4 = V4a × (R2 + R4) / (V + R4 × I5a) (10)
Similarly, I4b = (V + R2 × I5b) / (R2 + R4) = V4b / R4 (11)
R4 = V4b × (R2 + R4) / (V + R4 × I5b) (12)
From the calculation results of both formulas (10) and (12), V4a × (R2 + R4) / (V + R2 × I5a) = V4b × (R2 + R4) / (V + R2 × I5b)
From this, the positive-side insulation resistance R2 is
R2 = (V4a−V4b) × V / (V4b × I5a−V4a × I5b) (13)
Is obtained.

なお、分圧用の切替手段42において2つの接点を用いた場合について説明したが、接点は必ずしも接触子を意味するものではなく、論理回路(素子)やトランジスタなど利用でも良く、要は分圧比を変ることで検出用抵抗体に流れる電流が変化し、絶縁抵抗値を同様に求めることが出来るようにするものである。   Although the case where two contacts are used in the voltage dividing switching means 42 has been described, the contact does not necessarily mean a contact, and may be a logic circuit (element), a transistor, or the like. By changing, the current flowing through the detection resistor changes, and the insulation resistance value can be obtained similarly.

また、本発明は分圧比を変える前の検出電流と、変えた後の検出電流及び電路電圧から各抵抗体の電圧、電流を求め、その差から演算により絶縁抵抗の値を求めるようにしているので、各分圧用抵抗体(補助分圧抵抗体を含む)と電流検出用抵抗体の値が既知であれば抵抗値は任意の値で良く、また、比率も任意でよい。   Further, according to the present invention, the voltage and current of each resistor is obtained from the detected current before changing the voltage dividing ratio, the detected current after changing the voltage, and the electric circuit voltage, and the value of the insulation resistance is obtained from the difference. Therefore, as long as the values of the voltage dividing resistors (including the auxiliary voltage dividing resistors) and the current detecting resistors are known, the resistance values may be arbitrary values, and the ratios may be arbitrary.

1…直流電源
2…正極側電路
3…負極側電路了承
4…絶縁監視装置
41…電路電圧検出手段
42…分圧比の切替手段
43…電流検出手段
44…接地線
45…増幅回路
46…A/D変換器
47…演算手段
48…切替制御手段
49…計測表示手段
50…警報手段
DESCRIPTION OF SYMBOLS 1 ... DC power supply 2 ... Positive electrode side electric circuit 3 ... Negative electrode side electric circuit approval 4 ... Insulation monitoring device 41 ... Electric circuit voltage detection means 42 ... Voltage division ratio switching means 43 ... Current detection means 44 ... Ground line 45 ... Amplifying circuit 46 ... A / D converter 47 ... calculating means 48 ... switching control means 49 ... measurement display means 50 ... alarm means

Claims (3)

直流非接地式電路の電路電圧を検出する電路電圧検出手段と、この電路電圧を分圧する
分圧用抵抗体R1、R3と、この分圧用抵抗体の分圧比を補助分圧抵抗体R6を正極側と負極
側に交互に切り替えて分圧比を変更する切替手段と、該切替手段と大地間に設けられ大地
間に流れる電流を検出する電流検出手段と、該電流検出手段で検出した検出信号と前記の
電路電圧検出手段で検出した検出信号を入力し正極側に切替えたときの電路と大地間の電
流信号と負極側に切替えたときの電路と大地間の電流信号から絶縁抵抗値を演算する演算
手段と、該演算手段で演算した絶縁抵抗値を表示する計測表示手段及び又は警報手段を備
え、正極側絶縁抵抗をR2、負極側絶縁抵抗をR4としたときのR2とR4の絶縁抵抗値の演算手
段による算出は次の演算式で求めることを特徴とする直流非接地式電路の絶縁監視装置。
R2=(V4a−V4b)×V/(V4b×I5a−V4a×I5b)
R4=(V2b−V2a)×V/(V2b×I5a−V2a×I5b)
但し、Vは電路電圧、R1、R3は分圧用抵抗体、R6は補助分圧抵抗体、R5は電流検出手段に
有する検出用抵抗体でこれらの値は既知。V2、V4は電圧で、これに付されている数字の抵
抗体の電圧、Iは電流を示しこれに付されている数字の抵抗に流れる電流。a,bは切替
手段での切り替えオン接点を示す。なお、V4aは、V3a−V5a、V4bは、V3b−V5b、V2a
は、V1a+V5a、V2bは、V1b+V5bで求まる。
Circuit voltage detection means for detecting the circuit voltage V of the DC ungrounded circuit, voltage dividing resistors R1 and R3 for dividing the circuit voltage, and the voltage dividing ratio of the voltage dividing resistor to the auxiliary voltage dividing resistor R6 as the positive electrode Switching means for alternately switching between the side and the negative electrode side to change the voltage dividing ratio, a current detection means for detecting a current flowing between the switching means and the ground, and a detection signal detected by the current detection means, An insulation resistance value is calculated from the current signal between the electric circuit and the ground when the detection signal detected by the electric circuit voltage detection means is input and switched to the positive side, and the current signal between the electric circuit and the ground when switched to the negative side. Insulation resistance value of R2 and R4 with calculation means and measurement display means and / or alarm means for displaying the insulation resistance value calculated by the calculation means, where R2 is the positive side insulation resistance and R4 is the negative side insulation resistance Use the following formula to calculate DC Nonreferenced paths of insulation monitoring apparatus characterized by.
R2 = (V4a−V4b) × V / (V4b × I5a−V4a × I5b)
R4 = (V2b−V2a) × V / (V2b × I5a−V2a × I5b)
However, V is a circuit voltage, R1 and R3 are voltage dividing resistors, R6 is an auxiliary voltage dividing resistor, and R5 is a detection resistor included in the current detection means, and these values are known. V2 and V4 are voltages, the voltage of the numerical resistor attached thereto, and I is the current flowing through the numerical resistor attached thereto. a and b indicate switching-on contacts in the switching means. V4a is V3a-V5a, V4b is V3b-V5b, V2a.
V1a + V5a and V2b are obtained by V1b + V5b.
直流非接地式電路の電圧を分圧用抵抗体で分圧し、分圧用抵抗体の分圧点
と大地間に分圧比を切り替え変更する切替手段を設け、この切替手段と大地間に、分圧点
と大地間に流れる電流を検出する検出手段を設けるとともに、切替手段は正極側と負極側
の分圧用抵抗体に補助分圧抵抗体を交互に接続して分圧比を変更し、絶縁抵抗側と分圧抵
抗側に強制的に電圧差を発生させ、夫々変更したときに流れる夫々の電流を電流検出手段
で検出し、この検出した夫々の電流と電路間電圧から演算手段によって正極電路と大地間
、負極電路と大地間の絶縁抵抗値を算出し、算出した値を基に計測表示手段に表示及び又
は警報手段で警報するようにしたことを特徴とする直流非接地式電路の絶縁監視方法。
A switching means is provided to divide the voltage of the DC ungrounded circuit with a voltage dividing resistor and switch the voltage dividing ratio between the voltage dividing point of the voltage dividing resistor and the ground, and the voltage dividing point between the switching means and the ground. Detecting means for detecting the current flowing between the ground and the ground, and the switching means alternately connects the auxiliary voltage dividing resistors to the voltage dividing resistors on the positive electrode side and the negative electrode side to change the voltage dividing ratio, A voltage difference is forcibly generated on the voltage dividing resistor side, and each current flowing when each is changed is detected by the current detection means, and between the detected current and the voltage between the electric circuits, the calculation means calculates the current between the positive circuit and the ground. An insulation monitoring method for a DC non-grounded circuit characterized in that an insulation resistance value between the negative electrode circuit and the ground is calculated and displayed on the measurement display means and / or alarmed by the alarm means based on the calculated value.
請求項2における絶縁抵抗値の演算は、分圧用抵抗体をR1、R3、補助
分圧抵抗体R6及び検出用抵抗体をR5とし、正極電路と大地間の絶縁抵抗をR2、負極電路
と大地間の絶縁抵抗をR4としたとき次の演算式で求めることを特徴とする請求項2記載
の直流非接地式電路の絶縁監視方法。
R2=(V4a−V4b)×V/(V4b×I5a−V4a×I5b)
R4=(V2b−V2a)×V/(V2b×I5a−V2a×I5b)
但し、Vは電路電圧、R1、R3は分圧用抵抗体、R6は補助分圧抵抗体、R5は電流検出手
段に有する検出用抵抗体でこれらの値は既知。V2、V4は電圧で、これに付されている数字
の抵抗体の電圧、Iは電流を示しこれに付されている数字の抵抗に流れる電流。a,bは
切替手段での切り替えオン接点を示す。なお、V4aは、V3a−V5a、V4bは、V3b−V5b、V
2aは、V1a+V5a、V2bは、V1b+V5bで求まる。
The calculation of the insulation resistance value in claim 2 is as follows: R1 and R3 are voltage dividing resistors, R5 is an auxiliary voltage dividing resistor R6, and R5 is a detection resistor; R2 is an insulation resistance between the positive electrode circuit and the ground; 3. A method for monitoring insulation of a DC non-grounded circuit according to claim 2, wherein the insulation resistance between the two is determined by the following calculation formula when R4 is R4.
R2 = (V4a−V4b) × V / (V4b × I5a−V4a × I5b)
R4 = (V2b-V2a) x V / (V2b x I5a-V2a x I5b)
However, V is a circuit voltage, R1 and R3 are voltage dividing resistors, R6 is an auxiliary voltage dividing resistor, and R5 is a detection resistor included in the current detection means, and these values are known. V2 and V4 are voltages, the voltage of the numerical resistor attached thereto, and I is the current flowing through the numerical resistor attached thereto. a and b indicate switching-on contacts in the switching means. V4a is V3a-V5a, V4b is V3b-V5b, V
2a is obtained by V1a + V5a, and V2b is obtained by V1b + V5b.
JP2012007602A 2012-01-18 2012-01-18 Insulation monitoring device and monitoring method for DC ungrounded circuit Expired - Fee Related JP5514842B2 (en)

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