JP4093619B2

JP4093619B2 - Ground fault indicator and short circuit ground fault detection circuit for power transmission and distribution lines

Info

Publication number: JP4093619B2
Application number: JP30763697A
Authority: JP
Inventors: 弘米井; 宏明斎藤
Original assignee: Nichiyu Giken Kogyo Co Ltd
Current assignee: NiGK Corp
Priority date: 1997-11-10
Filing date: 1997-11-10
Publication date: 2008-06-04
Anticipated expiration: 2017-11-10
Also published as: JPH11142463A

Description

【０００１】
【発明の属する技術分野】
本発明は、電力送配電線の地絡点を表示する表示器、およびその表示器に使用される短絡と地絡を判別する回路に関するものである。
【０００２】
【従来の技術】
発電所や変電所の間で高電力エネルギを給配電するために、支持体、例えば鉄塔、パンザマスト、コンクリート電柱等に支持されて電力送配電線が張られている。かかる電力送配電線で、電力線に雷撃があると、電力線の電位が大幅に上がり、碍子の絶縁能力を超えて雷サージ電流が電力線から支持体に流れ込む、いわゆる正閃絡が発生する。このような雷撃の予防策として電力線の上部に架空地線が張られているが、張られていない送配電線もある。架空地線の有無に拘わらず、支持体に雷が落ちたときには支持体の電位が大幅に上がり、やはり碍子の絶縁能力を超えると雷サージ電流が電力線に流れ込み、いわゆる逆閃絡が発生する。
【０００３】
このような閃絡で、一旦、放電路が形成されると、その放電路に沿って送配電線から電流が大地に流れ込む地絡故障が発生し、碍子を破損することも多い。また鳥獣が碍子の近傍に来て感電し、地絡故障が発生することもある。
【０００４】
従来、地絡故障の発生した支持体を知るため、例えば特開平１−２８２４７３号公報に、架空地線のある場合には電力線より上部の支持体と同じく下部の支持体とに変流器を取付け、支持体に分流する地絡電流を検出し、架空地線のない場合には電力線より下部に流れる地絡電流を検出し、その出力で微少火薬を発火させて表示体を表示する地絡点表示器が記載されている。
【０００５】
【発明が解決しようとしている課題】
同公報に記載の地絡点表示器は、架空地線のある電力送配電線では、地絡故障が発生した支持体だけを表示することが可能である。しかし架空地線のない電力送配電線で、図３（Ａ）に示す送電線１と２の間が短絡し数千アンペアの電流Ｉdが流れる短絡故障が発生すると、検出コイル６に誘起される二次側出力電圧が大きいため、故障点より電源側の支持体に取り付けた地絡点表示器７のすべてが動作してしまい、故障の発生箇所を特定できないという問題があった。
【０００６】
本発明は、前記のような従来の地絡点表示器の欠点を解消するためなされたもので、単独の電流センサにより、架空地線の有無に拘わらず短絡電流で誤動作することがなく、正確に地絡故障箇所を検出できる電力送配電線の地絡点表示器およびその表示器に使用される短絡地絡判別回路を提供することを目的とする。
【０００７】
【課題を解決するための手段】
電力の送配を司る発電所や変電所には設備保護のため、送配電線に発生する短絡故障があったときに作動する継電器（ブレーカー）と、地絡故障があったときに作動する継電器とが設置されている。通常、短絡故障の電流は地絡故障の電流に比べて大きいため、短絡用継電器は地絡用継電器よりも短時間で作動するようになっている。本発明の発明者はこの点に着目し、前記の目的を達成するための本発明を完成するに至った。本発明を適用する電力送配電線の地絡点表示器および短絡地絡判別回路を実施例に対応する図面により説明すると、以下のとおりである。
【０００８】
本発明の地絡点表示器は、支持体４（図３参照）に張架され、短絡発生時に電力供給を遮断する短絡用継電器（不図示）および地絡発生時に電力供給を遮断する地絡用継電器（不図示）を接続してある電力送配電線１・２・３の、各支持体位置における地絡を表示する表示器において、図１に示すように、短絡電流Ｉdまたは地絡電流Ｉeの磁界を検出する検出コイル６に生じた誘導電流を整流する整流回路１１と、整流回路１１の出力を定電流に抑える定電流回路１２と、定電流回路１２の出力により充電される時定数回路１３と、時定数回路１３の両端電圧を検出する電圧レベル検出回路１４とを有する判別回路部１０に、電圧レベル検出回路１４による検出電圧を動作トリガとする表示部７が接続されている。
時定数回路１３がＲＣ回路で構成され、その時定数は、定電流回路１２の出力により、短絡発生から電力供給が遮断されるまで充電しても設定電圧まで充電されないが、地絡発生から電力供給が遮断されるまでに充電するとその設定電圧に充電される値である。
【０００９】
また本発明の短絡地絡判別回路は、図１に示すように、短絡発生時に電力供給を遮断する短絡用継電器および地絡発生時に電力供給を遮断する地絡用継電器を接続してある電力送配電線１・２・３の、短絡電流Ｉdまたは地絡電流Ｉe（図３参照）の磁界を検出して誘導電流を生ずる検出コイル６と、その誘導電流を整流する整流回路１１と、整流回路１１の出力を定電流に抑える定電流回路１２と、定電流回路１２の出力により充電される時定数回路１３と、時定数回路１３の両端電圧を検出する電圧レベル検出回路１４とを有している。
該時定数回路１３がＲＣ回路で構成され、その時定数は、定電流回路１２の出力により、短絡発生から電力供給が遮断されるまで充電しても設定電圧まで充電されないが、地絡発生から電力供給が遮断されるまでに充電するとその設定電圧に充電される値である。
【００１０】
この短絡地絡判別回路の動作は以下のとおりである。短絡があると電力送配電線１と２の間に短絡電流Ｉdが流れ、地絡があると電力送配電線１と支持体４の間に地絡電流Ｉeが流れるから、検出コイル６はこれら短絡電流Ｉdまたは地絡電流Ｉeによる磁界により誘導電流が生ずる。検出コイル６に、短絡による誘導電流を生ずるのは短絡発生から短絡用継電器が遮断するまでの時間で相対的に短く、地絡による誘導電流を生ずるのは地絡発生から地絡用継電器が遮断するまでの時間で長い。この誘導電流は判別回路部１０に流入し、整流回路１１で整流されてから定電流回路１２により一定に抑えられ、時定数回路１３に充電される。このとき短絡による誘導電流は短時間であるから、時定数回路１３に充電される電気量が少ないので両端電圧は低い。地絡による誘導電流は長時間流れるから、時定数回路１３に充電される電気量が多いので、両端電圧は高くなる。この両端電圧を電圧レベル検出回路１４で検出することにより短絡故障と地絡故障の判別をすることができる。
【００１１】
短絡地絡判別回路が上記のとおり動作するので、判別回路部１０に表示部７が接続した本発明の地絡点表示器は、検出コイル６が地絡電流Ｉeの磁界を検出すると、その誘導電流により判別回路部１０が動作して、表示部７が動作する。しかし短絡電流Ｉdの磁界を検出コイル６が検出しても、その誘導電流によっては表示部７が動作しない。したがって地絡電流が流れたときだけ動作することになる。
【００１２】
時定数回路１３は、図２に示すとおり、抵抗２２とコンデンサー２１のＲＣ回路で構成することができる。その時定数は、定電流回路１２の出力により、短絡発生から電力供給が遮断されるまでの時間を充電しても設定電圧まで充電されないが、地絡発生から電力供給が遮断されるまでの時間を充電するとその設定電圧に充電される値であるように、抵抗２２とコンデンサー２１の値を定める。
【００１３】
【発明の実施の形態】
以下、本発明の実施例を図面により詳細に説明する。
【００１４】
図１は本発明を適用する電力送配電線の地絡点表示器および短絡地絡判別回路の実施例の全体ブロック図である。図２は同じく地絡点表示器および短絡地絡判別回路の実施例の要部の回路図である。図３は同じく地絡点表示器および短絡地絡判別回路の取り付け状態を示す図である。
【００１５】
図１に示すとおり本発明の短絡地絡判別回路は、検出コイル６に判別回路部１０が接続されている。同じく本発明の地絡点表示器は、検出コイル６に判別回路部１０が接続され、さらに表示部７が接続されている。判別回路部１０には、整流回路１１、定電流回路１２、時定数回路１３、および電圧レベル検出回路１４を有している。
【００１６】
検出コイル６は、図３に示すとおり、支持体４の脚に、地絡電流Ｉeによる磁界を検知できるように取り付けられる。表示部７は、ニクロム線など発熱抵抗体に接して火薬が配置してあり、その火薬が発火したガス圧により、折り畳んで収納されている表示布が広がって垂れ下がるような従来から知られたものである。この表示部７は、同じく支持体４の広範囲な遠方から視認できるような位置に取り付けられる。尚、判別回路部１０は、検出コイル６と表示部７との中間の任意の位置に取り付けることができるが、本例では表示部７に一体化してある。
【００１７】
判別回路部１０の整流回路１１は、従来知られた回路が使用される。同じく定電流回路１２は、図２に示すとおり、定電流ダイオード２０により構成される。このため整流回路１１の出力は波形を有する脈流であるが、整流回路１１の出力レベルが一定以上のところでは、定電流ダイオード２０のカソードから定電流が取り出される。時定数回路１３は、抵抗２２とコンデンサ２１からなるＲＣ回路である。このＲＣ回路の時定数は抵抗２２の抵抗値とコンデンサ２１の容量で定められ、コンデンサ２１が短絡発生から電力供給が遮断されるまでの時間内に設定電圧になるまで充電されず、地絡発生から電力供給が遮断されるまでの時間内に設定電圧になるまで充電される値にする。
【００１８】
電圧レベル検出回路１４は、サイリスタ２４が直列に挿入され、入力側であるアノードとゲートの間は抵抗２５とコンデンサ２６のＲＣ回路で連結されている。サイリスタ２４のゲートはツェナーダイオード２３のカソードが接続されている。このため電圧レベル検出回路１４に入力し抵抗２５を介してツェナーダイオード２３に加えられる電圧が、ツェナー電圧より低く維持されれば、ツェナーダイオード２３は遮断状態でサイリスタ２４のゲート電圧は降下しないから、サイリスタ２４はオフを維持する。同様にしてツェナーダイオード２３に加えられる電圧が、ツェナー電圧より高くなると、ツェナーダイオード２３は導通するから、抵抗２５によりサイリスタ２４のゲート電圧は降下してサイリスタ２４はオンとなる。したがってツェナーダイオード２３のツェナー電圧と抵抗２５の値は、電圧レベル検出回路１４の動作電圧を決定することになる。
【００１９】
上記した図１および図２に示す短絡地絡判別回路は、以下のように動作する。
【００２０】
短絡があると電力送配電線１と２の間に短絡電流Ｉdが流れる。検出コイル６は地絡電流Ｉeの磁界を検知できるように取り付けられてはいるが、短絡電流Ｉdの磁界も検出してしまい誘導電流を生ずる。この誘導電流は整流回路１１で整流されてから定電流ダイオード２０により一定電流以下となり、コンデンサ２１に蓄えられる。このとき短絡による誘導電流は短時間であるから、コンデンサ２１と抵抗２２の時定数により抵抗２２の両端電圧、すなわち電圧レベル検出回路１４に入力する電圧は低い。入力電圧が低いと、ツェナーダイオード２３は遮断状態のままであるから、サイリスタ２４はオフとなっており、電圧レベル検出回路１４から出力がない。
【００２１】
一方、地絡があると電力送配電線１と支持体４の間に地絡電流Ｉeが流れ、これによる磁界を検出してコイル６に誘導電流が生ずる。この誘導電流は整流回路１１で整流されてから定電流ダイオード２０により一定電流以下となり、コンデンサ２１に蓄えられる。このとき地絡による誘導電流は長時間であるから、コンデンサ２１と抵抗２２の時定数により抵抗２２の両端電圧、すなわち電圧レベル検出回路１４に入力する電圧は高い。入力電圧が高いと、ツェナーダイオード２３は導通するから、サイリスタ２４はオンとなって、電圧レベル検出回路１４から出力が得られる。このように短絡地絡判別回路は、地絡があると電圧レベル検出回路１４から出力が得られるが、短絡があっても前記のように出力がないので短絡と地絡の判別ができることになる。
【００２２】
上記した検出コイル６に判別回路部１０が接続された短絡地絡判別回路に、さらに表示部７が接続されている地絡点表示器は、短絡があっても電圧レベル検出回路１４から出力がないので、表示部７は動作しない。地絡があると電圧レベル検出回路１４から出力があるから、表示部７の発熱抵抗体に電流が流れて発熱し、火薬が発火しそのガス圧により、折り畳んで収納されている表示布が広がって垂れ下がり、広範囲な遠方からでも地絡があった支持体４を視認できる。
【００２３】
上記した構成の短絡地絡判別回路は、検出コイル６で検出した電流値が定電流回路１２で一定電流以下に抑えられて、短絡用継電器が遮断するまでの時間よりも、地絡発生から電圧レベル検出回路１４から出力が得られるまでの時間を長くできる。すなわち図４に示すように、検出コイル６が検出した電流値に対して、定電流回路１２のある短絡地絡判別回路の作動（実線示）の不感帯の時間Ｔ₁を、短絡用継電器の作動時間Ｔ₀より長くしかも一定にできる。したがって、短絡によって誤動作することがない。仮に定電流回路１２がない短絡地絡判別回路についてみると、その作動（点線示）の不感帯の時間Ｔ₂は短絡用継電器の動作より短く、短絡によって誤動作する可能性がある。
【００２４】
判別回路部１０の動作確認のため、図５に示す試験回路で試験した。試験回路は、交流電源ＡＣにスライドレギュレーター２７およびステップダウントランス２９が接続され、その出力にスイッチ２８、電流計３０を経て継電器３１が接続され閉回路になっている。その閉回路部分に検出コイル６が取り付けられ、継電器３１が接続されている。検出コイル６の出力はオシロスコープ３２に接続される一方で判別回路部１０に接続され、判別回路部１０の出力が同じくオシロスコープ３２に接続されている。前記のように、送配電線における短絡電流は地絡電流に比べて大きいため、短絡用継電器は地絡用継電器よりも短時間で作動するようになっているので、短絡電流を模擬して試験する場合の継電器３１は遮断動作時間が１００ｍｓのものを取り付け、地絡電流を模擬して試験する場合の継電器３１は遮断動作時間が３００ｍｓのものを取り付ける。
【００２５】
この試験回路で、先ず地絡の模擬電流について試験した。回路から継電器３１を外して短絡しておき、電流計３０が１０Ａ、１００Ａ、２００Ａになる電圧をスライドレギュレーター２７に記しておく。遮断動作時間が３００ｍｓの継電器３１を繋ぎ、スライドレギュレーター２７を通電電流が１０Ａになる位置に設定してからスイッチ２８を入れると、検出コイル６の出力および判別回路部１０の出力がオシロスコープ３２に表示される。このときの検出コイル６の出力時間はスイッチ２８を入れてから３００ｍｓ（継電器３１の遮断動作時間に同じ）であったが、判別回路部１０の出力はスイッチ２８を入れてから２００ｍｓ後に信号が現れた。同様に通電電流が１００Ａ、２００Ａについて調べたところ判別回路部１０の出力時間はともに１５０ｍｓとなった。
【００２６】
同様に短絡の模擬電流について試験した。遮断動作時間が１００ｍｓの継電器３１を繋ぎ、スライドレギュレーター２７を通電電流が５０Ａ、１００Ａ、２００Ａ、３００Ａについて調べた。検出コイル６の出力時間はスイッチ２８を入れてから１００ｍｓ（この時間で継電器３１が遮断）で、一方、判別回路部１０の出力は現れなかった。
【００２７】
上記の各試験からわかるように、地絡を模擬した電流を通電した場合、確実に判別回路部１０は動作し、動作に１５０ｍｓ以上の時間が必要なことがわかった。また短絡を模擬した電流を通電した場合、通電電流値が大きくても通電時間が短いため、判別回路部１０は動作せず、継電器３１が先に通電電流を遮断していることがわかった。
【００２８】
尚、前記した本発明の地絡点表示器の実施例では、電圧レベル検出回路１４は一定レベル以上の電圧を検出したとき導通するスイッチ回路となる構成で、検出コイル６の誘導電流を由来とし時定数回路１３に蓄えられたエネルギーがそのスイッチ回路を通って表示部７に供給される。すなわち電圧レベル検出回路１４の検出電圧は、動作トリガとして機能するとともに動作電圧そのものでもある。しかし、別途に独立の動作電源を設け、電圧レベル検出回路１４の検出電圧は信号としての動作トリガ機能をだけ持たせ、そのトリガ信号により動作電源からのエネルギーを表示部７に供給する構成でも実施できる。
【００２９】
【発明の効果】
以上、詳細に説明したように本発明を適用した電力送配電線の地絡点表示器は、装置がコンパクトかつ安価であるとともに、短絡故障で誤動作することがないので、確実かつ正確に地絡箇所を表示することができる。
【００３０】
また本発明を適用した電力送配電線の短絡地絡判別回路は、単独の電流センサにより、架空地線の有無に拘わらず短絡と地絡を判別することができ、誤判別することがない。
【図面の簡単な説明】
【図１】本発明を適用する電力送配電線の地絡点表示器および短絡地絡判別回路の実施例の全体ブロック図である。
【図２】本発明を適用する電力送配電線の地絡点表示器および短絡地絡判別回路の実施例の要部の回路図である。
【図３】電力送配電線の地絡点表示器および短絡地絡判別回路の取り付け状態を示す図である。
【図４】本発明を適用する電力送配電線の短絡地絡判別回路の作動時間を説明する図である。
【図５】本発明を適用する電力送配電線の短絡地絡判別回路の作動を試験する回路図である。
【符号の説明】
１・２・３は電力送配電線、４は支持体、６は検出コイル、７は表示部、１０は判別回路部、１１は整流回路、１２は定電流回路、１３は時定数回路、１４電圧レベル検出回路、２０は定電流ダイオード、２１はコンデンサ、２２は抵抗、２３はツェナーダイオード、２４はサイリスタ、２５は抵抗、２６はコンデンサ、２７はスライドレギュレーター、２８はスイッチ、２９はステップダウントランス、３０は電流計、３１は継電器、３２はオシロスコープ、Ｉdは短絡電流、Ｉeは地絡電流、Ｔ₀・Ｔ₁・Ｔ₂は作動までの不感帯の時間である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display that displays a ground fault point of a power transmission and distribution line, and a circuit that determines a short circuit and a ground fault used in the display.
[0002]
[Prior art]
In order to supply and distribute high power energy between power plants and substations, power transmission and distribution lines are stretched supported by a support, such as a steel tower, panza mast, concrete pole, and the like. In such a power transmission / distribution line, if there is a lightning strike on the power line, the potential of the power line is significantly increased, and a so-called positive flash is generated in which a lightning surge current flows from the power line to the support body, exceeding the insulation capacity of the insulator. As a preventive measure against such a lightning strike, an overhead ground wire is stretched above the power line, but there are also transmission and distribution lines that are not stretched. Regardless of the presence or absence of the overhead ground wire, when the lightning strikes on the support, the potential of the support rises significantly. If the insulation capacity of the insulator is exceeded, a lightning surge current flows into the power line and a so-called reverse flash occurs.
[0003]
Once a discharge path is formed by such a flashover, a ground fault occurs in which current flows from the power transmission / distribution line to the ground along the discharge path, and the insulator is often damaged. Birds and beasts may come near the lion and get an electric shock, resulting in a ground fault.
[0004]
Conventionally, in order to know the support in which a ground fault has occurred, for example, in Japanese Patent Application Laid-Open No. 1-282473, in the case of an aerial ground wire, a current transformer is installed on the lower support as well as the support above the power line. Install and detect ground fault current that shunts to the support. If there is no overhead ground wire, detect ground fault current that flows below the power line and ignite a small amount of explosives at the output to display the ground fault. A point indicator is described.
[0005]
[Problems to be solved by the invention]
The ground fault point indicator described in the publication can display only the support on which a ground fault has occurred in a power transmission / distribution line having an overhead ground wire. However, when a short-circuit fault occurs in a power transmission / distribution line having no overhead ground wire, the transmission lines 1 and 2 shown in FIG. Since the secondary side output voltage is large, all of the ground fault point indicators 7 attached to the support on the power source side from the failure point operate, and there is a problem that the location where the failure occurs cannot be specified.
[0006]
The present invention was made to eliminate the disadvantages of the conventional ground fault point indicator as described above. With a single current sensor, there is no malfunction due to a short-circuit current regardless of the presence of an overhead ground wire. An object of the present invention is to provide a ground fault point indicator for a power transmission and distribution line that can detect a ground fault fault location and a short-circuit ground fault determination circuit used for the indicator.
[0007]
[Means for Solving the Problems]
In order to protect equipment at power stations and substations that control power transmission and distribution, a relay that operates when there is a short-circuit fault that occurs in the transmission and distribution lines, and a relay that operates when there is a ground fault And are installed. Usually, since the short-circuit fault current is larger than the ground-fault fault current, the short-circuit relay operates in a shorter time than the ground-fault relay. The inventor of the present invention pays attention to this point and has completed the present invention for achieving the above object. A ground fault point indicator and a short-circuit ground fault determination circuit of a power transmission / distribution line to which the present invention is applied will be described below with reference to the drawings corresponding to the embodiments.
[0008]
The ground fault point indicator of the present invention is stretched over the support 4 (see FIG. 3), and is connected to a short-circuit relay (not shown) that cuts off power supply when a short circuit occurs, and a ground fault that cuts off power supply when a ground fault occurs. As shown in FIG. 1, the short-circuit current Id or the ground-fault current of the power transmission / distribution lines 1, 2, and 3 to which the power relays (not shown) are connected is displayed. A rectifier circuit 11 that rectifies the induced current generated in the detection coil 6 that detects the magnetic field Ie, a constant current circuit 12 that suppresses the output of the rectifier circuit 11 to a constant current, and a time constant that is charged by the output of the constant current circuit 12 A display unit 7 that uses a voltage detected by the voltage level detection circuit 14 as an operation trigger is connected to a determination circuit unit 10 that includes a circuit 13 and a voltage level detection circuit 14 that detects a voltage across the time constant circuit 13.
The time constant circuit 13 is constituted by an RC circuit, and the time constant is not charged up to the set voltage even if the power supply is cut off from the occurrence of a short circuit until the power supply is cut off by the output of the constant current circuit 12, but the power supply from the occurrence of the ground fault If the battery is charged before being shut off, it is charged to the set voltage.
[0009]
In addition, as shown in FIG. 1, the short-circuit ground fault determination circuit of the present invention has a power transmission connected to a short-circuit relay that shuts off power supply when a short-circuit occurs and a ground-fault relay that shuts off power supply when a ground fault occurs. Detecting coil 6 that generates an induced current by detecting the magnetic field of short circuit current Id or ground fault current Ie (see FIG. 3) of distribution lines 1, 2, and 3, rectifier circuit 11 that rectifies the induced current, and rectifier circuit 11 has a constant current circuit 12 that suppresses the output of 11 to a constant current, a time constant circuit 13 that is charged by the output of the constant current circuit 12, and a voltage level detection circuit 14 that detects a voltage across the time constant circuit 13. Yes.
The time constant circuit 13 is constituted by an RC circuit, and the time constant is not charged to the set voltage by the output of the constant current circuit 12 until the power supply is cut off from the occurrence of the short circuit, but the power from the occurrence of the ground fault It is a value that is charged to the set voltage when it is charged before the supply is cut off .
[0010]
The operation of this short-circuit ground fault determination circuit is as follows. When there is a short circuit, a short circuit current Id flows between the power transmission / distribution lines 1 and 2, and when there is a ground fault, a ground fault current Ie flows between the power transmission / distribution line 1 and the support 4, so that the detection coil 6 An induced current is generated by a magnetic field generated by the short-circuit current Id or the ground fault current Ie. An induction current caused by a short circuit in the detection coil 6 is relatively short in the time from the occurrence of a short circuit until the short circuit relay is cut off. An induced current caused by a ground fault is caused by the occurrence of a ground fault from the ground fault relay. It takes a long time to complete. The induced current flows into the determination circuit unit 10, is rectified by the rectifier circuit 11, is held constant by the constant current circuit 12, and is charged to the time constant circuit 13. At this time, since the induced current due to the short circuit is short, the amount of electricity charged in the time constant circuit 13 is small, so that the voltage across the terminals is low. Since the induced current due to the ground fault flows for a long time, the amount of electricity charged in the time constant circuit 13 is large, so that the voltage at both ends becomes high. By detecting the voltage between the both ends by the voltage level detection circuit 14, it is possible to discriminate between a short circuit fault and a ground fault.
[0011]
Since the short-circuit ground fault determination circuit operates as described above, the ground fault point indicator of the present invention in which the display unit 7 is connected to the determination circuit unit 10 is guided when the detection coil 6 detects the magnetic field of the ground fault current Ie. The discriminating circuit unit 10 operates by the current, and the display unit 7 operates. However, even if the detection coil 6 detects the magnetic field of the short-circuit current Id, the display unit 7 does not operate depending on the induced current. Therefore, it operates only when a ground fault current flows.
[0012]
As shown in FIG. 2, the time constant circuit 13 can be composed of an RC circuit including a resistor 22 and a capacitor 21. The time constant is not charged to the set voltage even if the time from the occurrence of a short circuit to the interruption of power supply is charged by the output of the constant current circuit 12, but the time from the occurrence of a ground fault to the interruption of the power supply is as it is charging value to be charged to the set voltage, determining the value of the resistor 22 and the condenser 2 1.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1 is an overall block diagram of an embodiment of a ground fault point indicator and a short-circuit ground fault determination circuit of a power transmission / distribution line to which the present invention is applied. FIG. 2 is a circuit diagram of a main part of an embodiment of the ground fault point indicator and the short circuit ground fault determination circuit. FIG. 3 is a view showing a state where the ground fault point indicator and the short-circuit ground fault discriminating circuit are attached.
[0015]
As shown in FIG. 1, in the short-circuit ground fault determination circuit of the present invention, a determination circuit unit 10 is connected to the detection coil 6. Similarly, in the ground fault point indicator of the present invention, the discrimination circuit unit 10 is connected to the detection coil 6, and the display unit 7 is further connected. The discrimination circuit unit 10 includes a rectifier circuit 11, a constant current circuit 12, a time constant circuit 13, and a voltage level detection circuit 14.
[0016]
As shown in FIG. 3, the detection coil 6 is attached to the leg of the support 4 so that a magnetic field due to the ground fault current Ie can be detected. The display unit 7 is conventionally known in which explosives are arranged in contact with a heating resistor such as a nichrome wire, and the display cloth stored in a folded manner spreads and hangs down due to the gas pressure ignited by the explosives. It is. Similarly, the display unit 7 is attached at a position where it can be seen from a wide range of the support 4. The discriminating circuit unit 10 can be attached to any position between the detection coil 6 and the display unit 7, but is integrated with the display unit 7 in this example.
[0017]
A conventionally known circuit is used as the rectifier circuit 11 of the determination circuit unit 10. Similarly, the constant current circuit 12 includes a constant current diode 20 as shown in FIG. For this reason, the output of the rectifier circuit 11 is a pulsating flow having a waveform, but when the output level of the rectifier circuit 11 is a certain level or higher, a constant current is taken out from the cathode of the constant current diode 20. The time constant circuit 13 is an RC circuit including a resistor 22 and a capacitor 21. The time constant of this RC circuit is determined by the resistance value of the resistor 22 and the capacitance of the capacitor 21, and is not charged until the capacitor 21 reaches the set voltage within the time from when the short circuit occurs until the power supply is cut off. The value is charged until the set voltage is reached within the time from when the power supply is cut off.
[0018]
In the voltage level detection circuit 14, a thyristor 24 is inserted in series, and the anode and gate on the input side are connected by an RC circuit of a resistor 25 and a capacitor 26. The gate of the thyristor 24 is connected to the cathode of the Zener diode 23. For this reason, if the voltage input to the voltage level detection circuit 14 and applied to the Zener diode 23 via the resistor 25 is kept lower than the Zener voltage, the Zener diode 23 is cut off and the gate voltage of the thyristor 24 does not drop. The thyristor 24 remains off. Similarly, when the voltage applied to the Zener diode 23 becomes higher than the Zener voltage, the Zener diode 23 becomes conductive, so that the gate voltage of the thyristor 24 is lowered by the resistor 25 and the thyristor 24 is turned on. Therefore, the Zener voltage of the Zener diode 23 and the value of the resistor 25 determine the operating voltage of the voltage level detection circuit 14.
[0019]
The short-circuit ground fault determination circuit shown in FIGS. 1 and 2 operates as follows.
[0020]
When there is a short circuit, a short circuit current Id flows between the power transmission and distribution lines 1 and 2. Although the detection coil 6 is mounted so as to detect the magnetic field of the ground fault current Ie, it also detects the magnetic field of the short-circuit current Id and generates an induced current. This induced current is rectified by the rectifier circuit 11, then becomes a constant current or less by the constant current diode 20, and is stored in the capacitor 21. At this time, since the induced current due to the short circuit is short, the voltage across the resistor 22, that is, the voltage input to the voltage level detection circuit 14 is low due to the time constant of the capacitor 21 and the resistor 22. When the input voltage is low, the Zener diode 23 remains cut off, so that the thyristor 24 is off and there is no output from the voltage level detection circuit 14.
[0021]
On the other hand, if there is a ground fault, a ground fault current Ie flows between the power transmission / distribution line 1 and the support 4, and a magnetic field due to this is detected to generate an induced current in the coil 6. This induced current is rectified by the rectifier circuit 11, then becomes a constant current or less by the constant current diode 20, and is stored in the capacitor 21. At this time, since the induced current due to the ground fault is a long time, the voltage across the resistor 22, that is, the voltage input to the voltage level detection circuit 14 is high due to the time constant of the capacitor 21 and the resistor 22. When the input voltage is high, the Zener diode 23 becomes conductive, so that the thyristor 24 is turned on and an output is obtained from the voltage level detection circuit 14. As described above, the short-circuit ground fault determination circuit can obtain an output from the voltage level detection circuit 14 when there is a ground fault, but even if there is a short circuit, since there is no output as described above, it is possible to distinguish between a short circuit and a ground fault. .
[0022]
Even if a short circuit is present, the output of the ground fault point indicator having the display unit 7 connected to the short circuit ground fault determination circuit in which the determination circuit unit 10 is connected to the detection coil 6 is output from the voltage level detection circuit 14. Since there is no, the display part 7 does not operate. When there is a ground fault, there is an output from the voltage level detection circuit 14, so a current flows through the heating resistor of the display unit 7 to generate heat, and the gunpowder is ignited, and the display cloth that is folded and stored is expanded by the gas pressure. The support body 4 having a ground fault can be visually recognized even from a wide distance.
[0023]
In the short-circuit ground fault determination circuit having the above-described configuration, the current value detected by the detection coil 6 is suppressed to a constant current or less by the constant current circuit 12 and the voltage from the occurrence of the ground fault is longer than the time until the short-circuit relay is cut off. The time until the output is obtained from the level detection circuit 14 can be lengthened. That is, as shown in FIG. 4, the dead time T ₁ of the operation (solid line) of the short-circuit ground fault determination circuit having the constant current circuit 12 with respect to the current value detected by the detection coil 6 is determined as the operation of the short-circuit relay. It can be longer than time T ₀ and constant. Therefore, no malfunction occurs due to a short circuit. If looking at the constant current circuit 12 is not short-circuited locations絡判filter circuit, the operation time T ₂ of the dead zone (dotted line shown) is shorter than the operation of the short-circuit relay, there is a possibility of malfunction by a short.
[0024]
In order to confirm the operation of the discriminating circuit unit 10, a test circuit shown in FIG. The test circuit is a closed circuit in which a slide regulator 27 and a step-down transformer 29 are connected to an AC power source AC, and a relay 31 is connected to the output via a switch 28 and an ammeter 30. The detection coil 6 is attached to the closed circuit portion, and the relay 31 is connected. The output of the detection coil 6 is connected to the oscilloscope 32 while being connected to the discrimination circuit unit 10, and the output of the discrimination circuit unit 10 is also connected to the oscilloscope 32. As mentioned above, since the short circuit current in the transmission and distribution lines is larger than the ground fault current, the short circuit relay is designed to operate in a shorter time than the ground fault relay. The relay 31 with a cutoff operation time of 100 ms is attached to the relay 31, and the relay 31 with a cutoff operation time of 300 ms is attached in the case of testing by simulating a ground fault current.
[0025]
In this test circuit, a ground fault simulated current was first tested. The relay 31 is removed from the circuit and short-circuited, and the voltage at which the ammeter 30 becomes 10 A, 100 A, and 200 A is recorded on the slide regulator 27. When the relay 31 having a cutoff operation time of 300 ms is connected and the slide regulator 27 is set to a position where the energizing current becomes 10 A and then the switch 28 is turned on, the output of the detection coil 6 and the output of the discrimination circuit unit 10 are displayed on the oscilloscope 32. Is done. At this time, the output time of the detection coil 6 was 300 ms after the switch 28 was turned on (same as the disconnection operation time of the relay 31), but the output of the discrimination circuit unit 10 appeared a signal 200 ms after the switch 28 was turned on. It was. Similarly, when the energization currents were examined for 100 A and 200 A, the output time of the discrimination circuit unit 10 was 150 ms.
[0026]
Similarly, a short circuit simulated current was tested. The relay 31 having a cut-off operation time of 100 ms was connected, and the slide regulator 27 was examined for energization currents of 50A, 100A, 200A, and 300A. The output time of the detection coil 6 was 100 ms after the switch 28 was turned on (the relay 31 was cut off at this time), while the output of the discrimination circuit unit 10 did not appear.
[0027]
As can be seen from the above tests, it was found that when a current simulating a ground fault was applied, the discriminating circuit unit 10 was surely operated, and it took 150 ms or more for the operation. In addition, it was found that when a current simulating a short circuit is applied, the determination circuit unit 10 does not operate because the energization time is short even if the energization current value is large, and the relay 31 previously cuts off the energization current.
[0028]
In the above-described embodiment of the ground fault point indicator of the present invention, the voltage level detection circuit 14 is a switch circuit that is turned on when a voltage of a certain level or higher is detected, and is derived from the induced current of the detection coil 6. The energy stored in the time constant circuit 13 is supplied to the display unit 7 through the switch circuit. That is, the detection voltage of the voltage level detection circuit 14 functions as an operation trigger and is an operation voltage itself. However, a separate operation power supply is provided, and the detection voltage of the voltage level detection circuit 14 has only an operation trigger function as a signal, and the energy from the operation power supply is supplied to the display unit 7 by the trigger signal. it can.
[0029]
【The invention's effect】
As described above in detail, the ground fault point indicator of the power transmission / distribution line to which the present invention is applied is compact and inexpensive and does not malfunction due to a short-circuit failure. The location can be displayed.
[0030]
Moreover, the short circuit ground fault determination circuit of the power transmission and distribution line to which the present invention is applied can determine a short circuit and a ground fault regardless of the presence or absence of an overhead ground wire by a single current sensor, and does not make a false determination.
[Brief description of the drawings]
FIG. 1 is an overall block diagram of an embodiment of a ground fault point indicator and a short-circuit ground fault determination circuit of a power transmission and distribution line to which the present invention is applied.
FIG. 2 is a circuit diagram of a main part of an embodiment of a ground fault point indicator and a short-circuit ground fault determination circuit of a power transmission and distribution line to which the present invention is applied.
FIG. 3 is a diagram showing an attachment state of a ground fault point indicator and a short-circuit ground fault determination circuit of a power transmission and distribution line.
FIG. 4 is a diagram for explaining the operation time of a short-circuit ground fault determination circuit for a power transmission and distribution line to which the present invention is applied.
FIG. 5 is a circuit diagram for testing the operation of a short-circuit ground fault determination circuit for a power transmission and distribution line to which the present invention is applied.
[Explanation of symbols]
1, 2, 3 are power transmission / distribution wires, 4 is a support, 6 is a detection coil, 7 is a display unit, 10 is a discrimination circuit unit, 11 is a rectifier circuit, 12 is a constant current circuit, 13 is a time constant circuit, 14 Voltage level detection circuit, 20 is a constant current diode, 21 is a capacitor, 22 is a resistor, 23 is a Zener diode, 24 is a thyristor, 25 is a resistor, 26 is a capacitor, 27 is a slide regulator, 28 is a switch, 29 is a step-down transformer , 30 is an ammeter, 31 is a relay, 32 is an oscilloscope, Id is a short-circuit current, Ie is a ground fault current, and T ₀ , T _1, and T ₂ are dead zone times until operation.

Claims

The ground at the position of each support of the power transmission / distribution line that is connected to the support and is connected to the short-circuit relay that shuts off the power supply when a short-circuit occurs and the ground-fault relay that shuts off the power supply when a ground fault occurs In the indicator that displays the
A rectifier circuit that rectifies an induced current generated in a detection coil that detects a magnetic field of a short circuit current or a ground fault current, a constant current circuit that suppresses the output of the rectifier circuit to a constant current, and a battery that is charged by the output of the constant current circuit A display unit that uses a detection voltage by the voltage level detection circuit as an operation trigger is connected to a determination circuit unit having a time constant circuit and a voltage level detection circuit that detects a voltage across the time constant circuit ,
The time constant circuit is composed of an RC circuit, and the time constant is not charged up to the set voltage even if it is charged until the power supply is cut off from the occurrence of a short circuit due to the output of the constant current circuit. There earth絡点indicator, wherein values der Rukoto charged when charging to the set voltage before being cut off.

Inducted current is detected by detecting the short-circuit current or ground-fault magnetic field of the power distribution line connected to the short-circuit relay that cuts off the power supply when a short circuit occurs and the ground fault relay that cuts off the power supply when a ground fault occurs , A rectifier circuit that rectifies the induced current, a constant current circuit that suppresses the output of the rectifier circuit to a constant current, a time constant circuit that is charged by the output of the constant current circuit, and the time constant circuit And a voltage level detection circuit for detecting a voltage between both ends of
The time constant circuit is composed of an RC circuit, and the time constant is not charged up to the set voltage even if it is charged until the power supply is cut off from the occurrence of a short circuit due to the output of the constant current circuit. It is a value that is charged to the set voltage if it is charged before it is shut off,
A short circuit ground fault determination circuit, wherein a short circuit or a ground fault is determined based on a voltage detected by the voltage level detection circuit.