JP3639192B2 - Neutral point grounding resistance device - Google Patents

Description

【０００７】
となる。このように、図４に示す抵抗装置Ａにおいては、各抵抗器３間の電位差が非常に大きく、この結果、抵抗器３間の間隔を大きくすることはもとより、抵抗器３間に介在する支持碍子４や、抵抗器３と接地間に介在する支持碍子９においても、必然的に絶縁耐力に優れた大形のものを準備しなければならないので、設置スペースが少しばかり減少したとしても、抵抗装置Ａ自体の小形化を図ることが難しいため、抵抗装置Ａを小形で簡易に、かつ、経済的に製造することは困難であった。
【０００８】
その上、各抵抗器３は図４に示すように、抵抗素体２とケース１とが電気的に接続されているので、即ち、各抵抗器３には電位が与えられていることになる結果、ケース１自体が充電部となっているため、抵抗装置Ａの活線中に人が充電部に近づいたりすることによって、感電事故等を誘発するのを防ぐために、抵抗装置Ａの周囲には周囲柵１０が設置されている。
【０００９】
前記周囲柵１０の設置場所は、抵抗装置Ａの充電部との間の距離が、公称電圧階級によって異なるが、例えば、前記７７ｋＶ級の公称電圧においては、安全対策上充電部（ケース１）と周囲柵１０との最小水平距離は、１．５ｍ、周囲柵１０の高さは１．２ｍ以上とするように要求されている。
【００１０】
このように、抵抗装置Ａは自体の設置スペースの他に、人体が充電部に触れないように保護するためには、充電部（ケース１）から、例えば、最低１．５ｍ離れた位置（離隔距離）に周囲柵１０を施設することが基められていたので、結果的に設置スペースを低減することは難しく、抵抗装置Ａを設置するためにはある程度広いスペースが必要となるため、この種の抵抗装置Ａは市街地の狭隘な変電所等に設置することが難しく、結果的に市街地においても、変電所のスペースは必然的に広く必要とし、非常に不経済であった。
【００１１】
前記の問題を解消するために、最近では、抵抗素体をケースに収容して形成した抵抗器を、それぞれタンク内に支持碍子を介して必要段数積層して収容・固定し、この後、タンク内に絶縁用の六フッ化イオウガス（ＳＦ₆ ガス）等の絶縁ガスを充填・封入して構成した、所謂絶縁ガス封入形の中性点接地抵抗装置が使用されている。
【００１２】
前記絶縁ガス封入形の中性点接地抵抗装置においては、充電部となっている抵抗器とタンクとの間の空間に絶縁ガスを介在させることにより、充電部の露呈を防ぐように構成されているので、前記のように、充電部の露呈に伴う弊害を防止するための周囲柵を特別に設ける必要がないため、抵抗装置の設置スペースは相当節約することが可能となり、例えば、市街地の狭隘な地上、あるいは、地下式の変電所においても良好に設置することができ、至便である。
【００１３】
前記絶縁ガス封入形の抵抗装置は、絶縁ガスを使用する関係上、抵抗装置を施設するための離隔距離を大幅に低減して設置することができるという利便性が存在する反面、次のような問題があった。即ち、第１に抵抗器自体は、これまでと同様に抵抗素体をそれぞれケースに収納して１個づつ製造していたので、製作に手間と時間を要することはもとより、コスト高を招く要因となっていた。第２に抵抗器を複数台段積みにして収容するタンクは、絶縁ガスを充填している関係上、絶縁ガスが漏洩しないように気密性と耐圧力性を具備させて製造しなければならないので、タンクを製造する場合においても、抵抗器の製造と相まって抵抗装置の製造コストを必然的に高くするという問題があった。
【００１４】
更に、絶縁ガスは抵抗器に地絡電流が流れることによって生ずる熱により熱分解され、絶縁性能が大幅に劣化するため、絶縁ガスを定期的に点検し補充しなければならない等、抵抗装置の維持・管理に伴うメンテナンス業務も必要とする結果、それに伴う人手、費用等を必要とするという問題もあった。
【００１５】
本発明は、前記の種々な問題点に鑑み、簡素な構成で製造コストを低減させ、かつ、狭隘な設置スペースに良好に施設してメンテナンスフリーを実現した、簡易な構成の中性点接地抵抗装置を提供することにある。
【００１６】
【課題を解決するための手段】
本発明の中性点接地抵抗装置は、抵抗素体を抵抗取付枠体に所定の形状に配設して形成した抵抗器を上下方向に所定の絶縁間隔を保って複数段に積層し、前記各段の抵抗器を各段毎に接続導体を介して直列に接続し、かつ、各段の前記抵抗器を、各抵抗器間に介在させた絶縁碍子にて支持・固定することにより、前記各抵抗器を縦方向に所定段数積層して抵抗体を構成し、この抵抗体を接地電位のケースに所定数収容・施設して、気中絶縁方式の抵抗装置を構成するようにしたことを特徴とする。
【００１７】
又、本発明において前記抵抗体を所定数収容した接地電位のケースは、下部周縁に外気の流入口を、上部には流入した外気を排出する排出口をそれぞれ形成し、前記外気の流入口と排出口とによって接地電位ケース内に外気の流通路を形成するようにしたことを特徴とする。
【００１８】
本発明は、抵抗素体を直列に配列して抵抗取付枠体に取付けた抵抗器を縦方向に所定段数積層して抵抗体を形成し、この抵抗体を接地電位のケースに常時外気と接触させた状態で所定数収容・施設して気中絶縁方式の中性点接地抵抗装置を構成したので、抵抗装置は簡易な構成で大形化することなく、製造コストを良好に低減して製造することを可能とした。
【００１９】
即ち、本発明においては、各抵抗器を従来の抵抗器に比べてその分割数を増して、分割した各抵抗器間の電位差を小さくするとともに、各抵抗器を構成する抵抗素体は開放形の抵抗取付枠体に取付けるようにしたので、抵抗器自体は各抵抗器間の絶縁距離が縮小でき、これにより、抵抗器間の絶縁距離を維持する絶縁碍子の小形化が可能となり、結果的に前記抵抗器を所要数段積みして形成した抵抗体の小形・軽量化を容易とした。
【００２０】
前記抵抗体の小形化に伴い、これを複数台収容して抵抗装置を構成する接地電位ケースも必然的に小形化でき、しかも、前記各抵抗体は接地電位ケースに収容されているので、即ち、抵抗体を構成する充電部を露呈させた各抵抗器は接地電位ケースに収容することにより、従来のように、充電部を露呈させた抵抗器に比べ、接地場所における安全な離隔距離をあらかじめ設ける必要は全くない。又、前記充電部とケースとの間の絶縁距離は、前記離隔距離と一概に比較できないが、約半分程度に抑えることができる。
【００２１】
この場合、ケース内に絶縁ガスを封入した抵抗装置と比較すると、本発明は、気中絶縁方式を採用しているので、前記絶縁距離はやや長くなるものの、設置スペースにおいては大差ない。その上、本発明においては、気中絶縁方式の採用により、抵抗素体自体は接地電位ケースに収容されているものの、常時外気と接触させてあるので、抵抗素体に地絡電流が流れて発熱したとしても、抵抗素体は接地電位ケース内を流通する外気により、迅速・良好に冷却することができ利便である。
【００２２】
この結果、本発明においては、これまでの絶縁ガスを封入した抵抗装置に比べ、絶縁ガスを使用しない点、絶縁ガスを充填するためにケースの気密性を高める点、更に、絶縁ガスの定期的な補充が不要な点等、絶縁ガス封入方式の抵抗装置に対して著しく簡素な構成で、かつ、設置スペースにおいても大差なく低コストで製造することができる等優れた効果を有する。しかも、従来の気中絶縁方式の抵抗装置の如く、充電部を外部に露呈した場合に比べ、充電部が被覆されているので、設置スペースにおいても、安全を維持するための離隔距離を全く必要としないため、設置スペースが良好に低減することができ至便である。
【００２３】
【発明の実施の形態】
以下、本発明の実施例を図１ないし図３によって説明する。図１において、１１は鉄板等の金属板を建屋風に板金加工して形成した後述する抵抗体収容用の床面開放形の接地電位ケース（以下、ケースという）で、１２，１２ａは前記ケース１１内に所要数立設して収容した抵抗体で、本発明の中性点接地抵抗装置（以下抵抗装置という）Ｂは、大別すると前記ケース１１と抵抗体１２，１２ａによって構成されている。
【００２４】
次に前記抵抗体１２の構成について説明する。最初に耐熱性に優れた磁器材料からなる図示しない絶縁支持棒に、例えば、フェライト系の特殊鋼等からなる平角状に形成した線材を前記絶縁支持棒に設けた嵌合溝に螺旋状に巻回して抵抗素体１３（本例では４本）を形成し、この抵抗素体１３を、図１，３に示すように、金属板を断面凹字形に曲成した抵抗取付枠体１４に、一定の間隔を保って平行に並べてから、支持金具１５を用いて前記取付枠体１４に固定する。この後、各抵抗素体１３を接続板１６にて４本の抵抗素体１３を直列に接続して抵抗器１７を形成する。
【００２５】
つづいて、前記抵抗器１７を図１に示すように、ケース１１内で縦方向に段状に積層する。この場合は、ケース１１の開放された床面側に横梁１８を横架し、この横梁１８上に垂直に直立して取付けた第１の径大な絶縁碍子１９に、抵抗器１７を乗載して固定し、各抵抗器１７の抵抗取付枠体１４，１４間には、小径な第２の絶縁碍子２０をそれぞれ介在させて、抵抗器１７を所定段数積層して固定する。
【００２６】
前記のように、抵抗器１７を第２の絶縁碍子２０を用いて順次積層・固定することにより、前述した抵抗体１２を形成するものである。本例では、図１に示すように、抵抗器１７を６段に積層することにより第１の抵抗体１２を設ける。そして、前記抵抗体１２を構成する各抵抗器１７群は、それぞれ接続導体２１にて直列状態に接続する。なお、図２に示す１２ａは、前記第１の抵抗体１２と同様にして構成した第２の抵抗体であり、その構成は第１の抵抗体１２と全く同じであるため、説明は省略する。
【００２７】
前記第１，第２の抵抗体１２，１２ａは、図２で示すように、それぞれ最下段の抵抗器１７，１７同士を第２の接続導体２１ａにより電気的に接続されている。そして、前記第１の抵抗体１２は、最上段の抵抗器１７の入力側が、ケース１１上に樹立した中性点側ブッシング２２から導出されて図示しない変圧器巻線の中性点に接続する接続線２３と接続されており、又、第２の抵抗体１２ａは、その最上段に位置する抵抗器１７の出力側が、ケース１１上に樹立した接地側ブッシング２４から導出されてケース１１の側壁に取付けた変流器２５の入力端と接続する引出線２６と接続されている。
【００２８】
なお、前記変流器２５の出力端は接地線２７に接続されている。又、図１において、２８はケース１１の下部側壁に開口した横長な外気（空気）の流入口である。２９はケース１１の外側から流入口２８内に雨水が浸入するのを防ぐ防雨板であり、３０はケース１１内において流入口２８に被着した塵埃や害虫の侵入を防ぐフィルターである。
【００２９】
更に、図１に示す３１はケース１１の上面（屋根部分）に開口したケース１１内の空気を排出する排出口で、この排出口３１はその上部に被着した雨水避体３２により、雨水が排出口３１からケース１１内に流入するのを防ぎ、排出口３１のケース１１内に位置する内側には、流入口２８と同様に害虫等の侵入を防ぐフィルター３３が取付けられている。図２に示す３４はケース１１に設けた接地端子であり、図示しないアース線が接続されている。
【００３０】
次に動作について説明する。配電系統において、例えば、１線地絡事故等が発生し、図示しない変圧器の中性点に大きな地絡電流が流れると、この大電流は、接続線２３→抵抗体１２→第２の接続導体２１ａ→第２の抵抗体１２ａ→引出線２６→変流器２５→接地線２７に流れ、前記変圧器が地絡電流によって損傷するのを防止する。
【００３１】
そして、前記第１，第２の抵抗体１２，１２ａに大電流が流れると、抵抗体１２，１２ａを構成する各抵抗器１７内に組込まれている抵抗素体１３は、その抵抗分又は電力量に応じて発熱する。前記各抵抗素体１３に発生した熱は、抵抗素体１３の外部に放散される。即ち、ケース１１内に放散されることになる。
【００３２】
前記ケース１１内に放散された熱はそのままケース１１内を上昇し、ケース１１上部の排出口３１からケース１１外に排出される。一方、前記大電流によって発熱した抵抗素体１３はもとより、この抵抗素体１３から伝熱されて隣接する抵抗取付枠体１４等の部材も当然発熱するが、抵抗素体１３，抵抗取付枠体１４等抵抗装置Ｂを構成する各部材は、ケース１１の流入口２８から流入してケース１１上部の排出口３１から排出される外気にさらされることになる。
【００３３】
従って、前記抵抗素体１３等に残存している熱は、前記ケース１１内を流通する外気によって良好に発散が増長されてケース１１外に排除され、抵抗体１２，１２ａを迅速に冷却し、抵抗素体１３の発熱による劣化を抑制し、抵抗器１７の長期使用を可能とする。
【００３４】
次に、本発明の抵抗装置Ｂは、図２に示すように、抵抗器１７が１２分割されたものが例示されており、これは、７７ｋＶ級の配電線に抵抗装置Ｂを設置した場合、抵抗器１７間の電位差は、
【００３５】
【数２】

【００３６】
となる。これは従来の４分割した場合の１１ｋＶに比較すると電位差は約１／３となる。
【００３７】
各抵抗器１７間における前記電位差は、抵抗器１７を細かく分割すれば小さくすることは可能である。この場合、従来の抵抗器においても当然実施することは可能であるが、従来の各抵抗器は電位差を小さくしても充電部は依然として外部に露出しているため、抵抗器の動作時における安全性を考慮すれば、設置場所における離隔距離は必ず必要となり、抵抗器を細分化しても設置スペースを低減することは難しい。
【００３８】
然るに、本発明においては、例えば、抵抗器１７を、従来の４分割した抵抗器に対して１２分割することにより、抵抗器１７間の電位差が大幅に低減できるため、抵抗器１７間の絶縁距離が小さくでき、それに伴い抵抗器１７間を支持する絶縁碍子２０も必然的に小形化することが可能となる。しかも、各抵抗器１７群からなる抵抗体１２，１２ａは、接地電位のケース１１に収容設置されているので、安全性は十分確保することができるとともに、充電部となっている各抵抗器１７とケース１１壁面との間の絶縁距離は、種々テストを繰り返した結果、本例の７７ｋＶ級における機器の絶縁距離を設定するために、規格等により定められている安全対策上の寸法（７５０ｍｍ）は充分クリアすることができた。
【００３９】
即ち、従来の抵抗器を外部に直接設置した場合に比べ、人体への安全性を確保するための設置スペースを約半分程度に縮小して設置することが可能となり、抵抗装置Ｂの設置におけるコストの大幅低減が可能となる。更に、本発明においては、抵抗体１２，１２ａを収容したケース１１内に常に外気が流通するように形成されているので、抵抗装置Ｂの作動時において、抵抗体１２，１２ａの発熱処理が良好に行い得、抵抗体１２，１２ａを構成する抵抗素体１３の冷却を迅速・確実に行うことができる。
【００４０】
【発明の効果】
本発明は、以上説明したように、抵抗素体を直列に配列して抵抗取付枠体に取付けた抵抗器を縦方向に所定段数積層して抵抗体を形成し、この抵抗体を、底面を開放した接地電位のケースに常時外気と接触させた状態で所定数収容・施設して気中絶縁方式の中性点接地抵抗装置を構成したので、中性点抵抗装置を簡易な構成で大形化することなく、設置スペース及び製造コストを良好に低減して製造することを可能とした。
【００４１】
又、本発明は、各抵抗器を従来の抵抗器に比べてその分割数を増して、各抵抗器間の電位差を小さくし、かつ、各抵抗器を構成する抵抗素体を開放形の抵抗取付枠体に取付けるように構成したので、各抵抗器間の絶縁距離が縮小でき、この結果、抵抗器間の絶縁を維持する絶縁碍子の小形・軽量化が可能となり、前記抵抗器を所要数段積みして形成する抵抗体の小形・軽量化を良好に促進することができる。
【００４２】
更に、前記抵抗体の小形化に伴い、これを複数個収容して中性点接地抵抗装置を構成するために使用する接地電位ケースも必然的に小形化でき、しかも、前記各抵抗体を接地電位ケースに収容するように構成したので、従来のように、充電部を露呈させた抵抗器に比べ、設置場所における安全な離隔距離を設定する必要は全くないので、中性点接地抵抗装置の設置スペースを約半分程度に抑えることができる。
【００４３】
その上、本発明においては、気中絶縁方式の採用により、抵抗素体自体は接地電位ケースに収容されているものの、常時外気と接触するように構成されているので、抵抗素体に地絡電流が流れて発熱したとしても、抵抗素体は接地電位ケース内を流通する外気により、迅速・良好に冷却することができ利便である。
【図面の簡単な説明】
【図１】本発明の中性点接地抵抗装置の一部を切欠いて示す正面図である。
【図２】同じく本発明の中性点接地抵抗装置の一部を切欠いて示す側面図である。
【図３】本発明の中性点接地抵抗装置に用いる抵抗体の結線状態を説明する説明図である。
【図４】従来の中性点接地抵抗装置の設置状態を示す概略正面図である。
【図５】同じく概略側面図である。
【符号の説明】
１１ 接地電位ケース
１２，１２ａ 抵抗体
１３ 抵抗素体
１４ 抵抗取付枠体
１７ 抵抗器
１９，２０ 絶縁碍子
２８ 流入口
３１ 排出口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a neutral grounding resistance device for electric power that grounds a neutral point of a transformer winding through a resistance device.
[0002]
[Prior art]
As shown in FIG. 4, for example, a conventionally known neutral point grounding resistance device is configured by a plurality of resistors 3 formed by arranging resistor elements 2 in a grid in a case 1. Yes. When installing the resistors 3, due to the installation space, for example, as shown in FIG. 4, the resistors 3 are connected in series, stacked in two stages via the support insulators 4, and arranged in two rows. The resistor device A is configured in such a manner that the resistor device A is arranged in the transformer winding (not shown) via the insulator 5 and the connection line 6. 4 is connected to the ground line 8 via the ground-side bushing 7. Since each resistor 3 constituting the resistance device A is generally only insulated and cooled by the air insulation method, when the ground potential at the neutral point rises, the case 1 itself is a high voltage. As a result, a surrounding fence 10 such as a protective fence is generally provided around the installation place because of safety measures.
[0003]
[Problems to be solved by the invention]
However, since the resistance device A generally employs an air insulation system, the problem that the resistance device A itself is increased in size cannot be avoided. In addition, even if each resistor 3 is installed, it can be easily installed if it is in a horizontal single row state. However, in this case, since a considerable installation space is required, it is realistic. It wasn't.
[0004]
Therefore, as shown in FIG. 4, the installation space problem has been solved to some extent by stacking a predetermined number of resistors 3 from the horizontal one row state, but the resistance device A itself adopts an air insulation system. For this reason, the increase in size was inevitable, and this was a major factor that caused production costs to rise.
[0005]
That is, as shown in FIGS. 4 and 5, the resistor device A is configured by arranging the resistors 3 divided into four in two rows in the horizontal direction, each of which is stacked in two stages. For example, when the resistance device A is placed on a distribution line having a nominal voltage of 77 kV,
[0006]
[Expression 1]

[0007]
It becomes. As described above, in the resistance device A shown in FIG. 4, the potential difference between the resistors 3 is very large. As a result, not only the interval between the resistors 3 is increased, but also the support interposed between the resistors 3 is supported. Since the insulator 4 and the supporting insulator 9 interposed between the resistor 3 and the ground must inevitably be prepared with a large one having excellent dielectric strength, even if the installation space is slightly reduced, the resistance Since it is difficult to reduce the size of the device A itself, it has been difficult to manufacture the resistance device A in a small, simple and economical manner.
[0008]
In addition, as shown in FIG. 4, each resistor 3 is electrically connected to the resistor element 2 and the case 1, that is, each resistor 3 is given a potential. As a result, since the case 1 itself is a charging part, in order to prevent a person from approaching the charging part in the live line of the resistance device A and inducing an electric shock or the like around the resistance device A, A surrounding fence 10 is installed.
[0009]
The distance between the surrounding fence 10 and the charging unit of the resistance device A differs depending on the nominal voltage class. For example, in the 77 kV class nominal voltage, the charging unit (case 1) is used for safety measures. The minimum horizontal distance with the surrounding fence 10 is required to be 1.5 m, and the height of the surrounding fence 10 is 1.2 m or more.
[0010]
In this way, in addition to the installation space of the resistance device A, in order to protect the human body from touching the charging unit, for example, a position (separation) at least 1.5 m away from the charging unit (case 1). This is because it is difficult to reduce the installation space as a result, and a large space is required to install the resistance device A. It is difficult to install the resistance device A in a narrow substation or the like in an urban area. As a result, even in an urban area, the space for the substation is inevitably necessary and very uneconomical.
[0011]
In order to solve the above-described problem, recently, resistors formed by housing a resistor element in a case are respectively stacked and accommodated and fixed in tanks via supporting insulators, and then the tank There is used a so-called insulating gas-filled neutral point grounding resistance device in which an insulating gas such as sulfur hexafluoride gas (SF ₆ gas) for insulation is filled and sealed.
[0012]
In the neutral point grounding resistance device enclosed with the insulating gas, the insulating portion is interposed in the space between the resistor and the tank serving as the charging portion, thereby preventing the charging portion from being exposed. Therefore, as described above, it is not necessary to provide a special surrounding fence to prevent the harmful effects caused by the exposure of the live parts, so that the installation space for the resistance device can be saved considerably. It is convenient because it can be installed well even on the ground or underground substation.
[0013]
The insulating gas-sealed resistance device has the convenience that the separation distance for installing the resistance device can be greatly reduced due to the use of the insulating gas, but the following is present. There was a problem. That is, firstly, the resistors themselves are manufactured one by one by storing the resistor elements in the case as before, so that it takes time and effort to manufacture, and causes high costs. It was. Secondly, a tank that houses a plurality of resistors stacked must be manufactured with airtightness and pressure resistance so that the insulating gas does not leak because it is filled with insulating gas. Even when the tank is manufactured, there is a problem that the manufacturing cost of the resistor device is inevitably increased in combination with the manufacture of the resistor.
[0014]
In addition, the insulation gas is thermally decomposed by the heat generated by the ground fault current flowing through the resistor, and the insulation performance is greatly deteriorated. Therefore, the insulation gas must be regularly checked and replenished.・ As a result of the need for maintenance work accompanying management, there was also a problem that manpower and costs associated therewith were required.
[0015]
In view of the above-mentioned various problems, the present invention reduces the manufacturing cost with a simple configuration, and has a simple configuration with a good configuration in a narrow installation space and realizes maintenance-free. To provide an apparatus.
[0016]
[Means for Solving the Problems]
In the neutral point grounding resistance device of the present invention, a resistor formed by arranging a resistor element in a predetermined shape on a resistor mounting frame is stacked in a plurality of stages while maintaining a predetermined insulation interval in the vertical direction. By connecting the resistors of each stage in series via connecting conductors for each stage, and supporting and fixing the resistors of each stage with an insulator interposed between the resistors, A resistor is formed by stacking a predetermined number of resistors in the vertical direction, and a predetermined number of these resistors are accommodated and installed in a ground potential case to form a resistance device of the air insulation type. Features.
[0017]
In the present invention, a ground potential case containing a predetermined number of the resistors is formed with an outside air inlet at the lower periphery and an outlet for discharging the outside air at the top, An outside air flow path is formed in the ground potential case by the discharge port.
[0018]
The present invention forms a resistor by arranging a predetermined number of resistors in a vertical direction by arranging resistors arranged in series in a resistor mounting frame, and this resistor is always in contact with outside air in a case of a ground potential. Since a neutral point grounding resistance device with an air insulation system is configured by accommodating and installing a predetermined number of devices in a state of being allowed to operate, the resistance device can be manufactured with a simple structure and reduced in manufacturing cost without being increased in size. Made it possible to do.
[0019]
That is, in the present invention, each resistor is increased in the number of divisions as compared with the conventional resistors, the potential difference between the divided resistors is reduced, and the resistor element constituting each resistor is an open type. Because the resistor itself can be reduced in the insulation distance between each resistor, this makes it possible to reduce the size of the insulator that maintains the insulation distance between the resistors. Further, it is possible to easily reduce the size and weight of the resistor formed by stacking the required number of resistors.
[0020]
Along with the downsizing of the resistors, a ground potential case that accommodates a plurality of resistors to form a resistance device can inevitably be reduced in size, and each resistor is accommodated in a ground potential case. Each resistor that exposes the charging part that constitutes the resistor is housed in a ground potential case, so that a safe separation distance at the grounding location can be increased in advance as compared with a resistor that exposes the charging part as in the past. There is no need to provide it. Also, the insulation distance between the charging part and the case cannot be compared with the separation distance, but can be reduced to about half.
[0021]
In this case, compared with a resistance device in which an insulating gas is sealed in the case, the present invention employs an air insulation system, so the insulation distance is slightly longer, but the installation space is not much different. In addition, in the present invention, the resistance element itself is accommodated in the ground potential case by adopting the air insulation system, but since it is always in contact with the outside air, a ground fault current flows through the resistance element. Even if heat is generated, the resistor element can be conveniently and quickly cooled by the outside air flowing through the ground potential case.
[0022]
As a result, in the present invention, compared to conventional resistance devices encapsulating the insulating gas, the insulating gas is not used, the case is hermetically sealed to fill the insulating gas, and the insulating gas is periodically added. It has an excellent effect that it can be manufactured at a low cost without much difference in the installation space, with a remarkably simple configuration compared to the resistance device of the insulating gas sealing system, such as no need for replenishment. Moreover, compared to the case where the charging unit is exposed to the outside, as in the case of a conventional air-insulated resistance device, the charging unit is covered, so that a separation distance is required to maintain safety even in the installation space. Therefore, the installation space can be reduced well, which is convenient.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 11 denotes a ground potential case (hereinafter referred to as a case) for opening a resistor, which will be described later, which is formed by processing a metal plate such as an iron plate into a building style, and 12 and 12 a are the cases. The neutral point grounding resistance device (hereinafter referred to as a resistance device) B according to the present invention is composed of the case 11 and the resistors 12 and 12a. .
[0024]
Next, the configuration of the resistor 12 will be described. First, a rectangular wire made of, for example, ferritic special steel or the like, is spirally wound around a fitting groove provided on the insulating support rod. As shown in FIGS. 1 and 3, the resistor element 13 is formed on a resistor attachment frame 14 formed by bending a metal plate into a concave shape as shown in FIGS. After arranging them in parallel at a constant interval, they are fixed to the mounting frame 14 using the support fitting 15. Thereafter, each resistor element 13 is connected to the four resistor elements 13 in series by a connection plate 16 to form a resistor 17.
[0025]
Subsequently, as shown in FIG. 1, the resistor 17 is stacked in a step shape in the vertical direction in the case 11. In this case, a resistor 17 is mounted on a first large-sized insulator 19 that is mounted on a horizontal beam 18 on the floor surface of the case 11 that is open and mounted vertically upright on the horizontal beam 18. The resistor 17 is laminated by a predetermined number of stages and fixed between the resistance mounting frames 14 and 14 of the resistors 17 with the small-diameter second insulator 20 interposed therebetween.
[0026]
As described above, the resistor 17 is sequentially laminated and fixed using the second insulator 20 to form the resistor 12 described above. In this example, as shown in FIG. 1, the first resistor 12 is provided by stacking resistors 17 in six stages. Each group of resistors 17 constituting the resistor 12 is connected in series by a connection conductor 21. Note that 12a shown in FIG. 2 is a second resistor configured in the same manner as the first resistor 12, and since the configuration is exactly the same as that of the first resistor 12, description thereof is omitted. .
[0027]
As shown in FIG. 2, in the first and second resistors 12, 12a, the lowermost resistors 17, 17 are electrically connected to each other by a second connection conductor 21a. In the first resistor 12, the input side of the uppermost resistor 17 is led out from a neutral point side bushing 22 established on the case 11 and connected to a neutral point of a transformer winding (not shown). The second resistor 12 a is connected to the connection line 23, and the output side of the resistor 17 located at the uppermost stage of the second resistor 12 a is led out from the ground side bushing 24 established on the case 11, and the side wall of the case 11 It connects with the lead-out line 26 connected with the input end of the current transformer 25 attached to.
[0028]
The output terminal of the current transformer 25 is connected to the ground line 27. In FIG. 1, 28 is a laterally long outside air (air) inlet opening in the lower side wall of the case 11. Reference numeral 29 denotes a rainproof plate for preventing rainwater from entering the inflow port 28 from the outside of the case 11, and 30 is a filter for preventing intrusion of dust and pests attached to the inflow port 28 in the case 11.
[0029]
Further, reference numeral 31 shown in FIG. 1 is a discharge port for discharging air in the case 11 opened on the upper surface (roof portion) of the case 11, and this discharge port 31 receives rainwater by a rainwater escape body 32 attached to the upper portion. A filter 33 that prevents intrusion of pests and the like is attached to the inside of the discharge port 31 in the case 11 so as to prevent intrusion of pests and the like, as in the case of the inflow port 28. Reference numeral 34 shown in FIG. 2 denotes a ground terminal provided on the case 11, and a ground wire (not shown) is connected thereto.
[0030]
Next, the operation will be described. In the power distribution system, for example, when a one-line ground fault occurs and a large ground fault current flows through the neutral point of a transformer (not shown), this large current is connected to the connection line 23 → resistor 12 → second connection. The current flows through the conductor 21a → second resistor 12a → leader line 26 → current transformer 25 → ground line 27 to prevent the transformer from being damaged by a ground fault current.
[0031]
When a large current flows through the first and second resistors 12 and 12a, the resistor element 13 incorporated in each resistor 17 constituting the resistors 12 and 12a has its resistance or power. It generates heat according to the amount. The heat generated in each resistor element 13 is dissipated to the outside of the resistor element 13. That is, it is dissipated in the case 11.
[0032]
The heat dissipated in the case 11 rises as it is in the case 11 and is discharged out of the case 11 through the discharge port 31 at the top of the case 11. On the other hand, not only the resistance element 13 that has generated heat due to the large current but also the members such as the adjacent resistance attachment frame 14 that are transferred from the resistance element 13 naturally generate heat. Each member constituting the 14 equiresistance device B is exposed to outside air that flows in from the inlet 28 of the case 11 and is discharged from the outlet 31 at the top of the case 11.
[0033]
Therefore, the heat remaining in the resistor element 13 and the like is favorably increased by the outside air flowing through the case 11 and is removed from the case 11 to quickly cool the resistors 12 and 12a. Deterioration due to heat generation of the resistor element 13 is suppressed, and the resistor 17 can be used for a long time.
[0034]
Next, as shown in FIG. 2, the resistor device B of the present invention is illustrated in which the resistor 17 is divided into 12 parts. This is because when the resistor device B is installed on a 77 kV class distribution line, The potential difference between the resistors 17 is
[0035]
[Expression 2]

[0036]
It becomes. This is about 1/3 of the potential difference compared to 11 kV in the case of the conventional four division.
[0037]
The potential difference between the resistors 17 can be reduced by dividing the resistors 17 finely. In this case, the conventional resistor can naturally be implemented. However, since each of the conventional resistors is exposed to the outside even if the potential difference is reduced, safety during operation of the resistor is not possible. In consideration of the characteristics, the separation distance at the installation location is absolutely necessary, and it is difficult to reduce the installation space even if the resistors are subdivided.
[0038]
However, in the present invention, for example, by dividing the resistor 17 into 12 parts with respect to the conventional four-divided resistor, the potential difference between the resistors 17 can be greatly reduced. Accordingly, the insulator 20 that supports the resistor 17 can be inevitably reduced in size. In addition, since the resistors 12 and 12a made up of each group of the resistors 17 are accommodated and installed in the case 11 having the ground potential, safety can be sufficiently ensured and each resistor 17 serving as a charging unit can be secured. As a result of repeating various tests, the insulation distance between the wall of the case 11 and the case 11 is a dimension for safety measures (750 mm) determined by the standard to set the insulation distance of the equipment in the 77 kV class of this example. Was clear enough.
[0039]
That is, compared to the case where a conventional resistor is directly installed outside, the installation space for securing safety to the human body can be reduced to about half, and the cost for installing the resistor device B can be reduced. Can be greatly reduced. Further, in the present invention, since the outside air is always circulated in the case 11 containing the resistors 12, 12a, the heat generation processing of the resistors 12, 12a is good when the resistor device B is operated. Therefore, the resistor element 13 constituting the resistors 12 and 12a can be cooled quickly and reliably.
[0040]
【The invention's effect】
As described above, the present invention forms a resistor by arranging a predetermined number of resistors in a vertical direction by arranging resistors in series and arranging the resistors on the resistor mounting frame. A neutral grounding resistance device is configured with a simple structure because it is configured to accommodate and install a predetermined number of open ground potential cases that are always in contact with the outside air, and has an air insulation type neutral point grounding resistance device. Without making it possible, the installation space and the manufacturing cost can be reduced well.
[0041]
Further, the present invention increases the number of divisions of each resistor as compared with the conventional resistor, reduces the potential difference between the resistors, and opens the resistor element constituting each resistor to an open-type resistor. Since it is configured to be mounted on the mounting frame, the insulation distance between the resistors can be reduced. As a result, it is possible to reduce the size and weight of the insulator that maintains the insulation between the resistors. It is possible to favorably promote reduction in size and weight of resistors formed by stacking.
[0042]
Further, as the resistors are miniaturized, a ground potential case used to construct a neutral point grounding resistance device by accommodating a plurality of the resistors can be inevitably reduced in size, and each resistor is grounded. Since it is configured to be accommodated in the potential case, it is not necessary to set a safe separation distance at the installation location as compared with a resistor that exposes a charged part as in the conventional case. Installation space can be reduced to about half.
[0043]
In addition, in the present invention, since the resistance element itself is accommodated in the ground potential case by adopting the air insulation system, it is configured so as to be always in contact with the outside air. Even if current flows and heat is generated, the resistor element can be conveniently and quickly cooled by the outside air flowing through the ground potential case.
[Brief description of the drawings]
FIG. 1 is a front view showing a neutral point grounding resistance device according to the present invention with a part thereof cut away.
FIG. 2 is a side view of the neutral grounding resistance device according to the present invention, partly cut away.
FIG. 3 is an explanatory diagram for explaining a connection state of a resistor used in a neutral point grounding resistance device of the present invention.
FIG. 4 is a schematic front view showing an installation state of a conventional neutral point grounding resistance device.
FIG. 5 is a schematic side view of the same.
[Explanation of symbols]
11 Ground potential case 12, 12a Resistor 13 Resistor element 14 Resistor mounting frame 17 Resistor 19, 20 Insulator 28 Inlet 31 Inlet 31

Claims (2)

Resistors formed by arranging resistor elements in a predetermined shape on the resistor mounting frame are stacked in multiple stages with a predetermined insulation interval in the vertical direction, and the resistors at each stage are connected to each stage. The resistors are stacked in series in a vertical direction by connecting and connecting the resistors in series via conductors and supporting and fixing the resistors at each stage with an insulator interposed between the resistors. A neutral point grounding resistance device comprising a resistor, and a predetermined number of the resistors are accommodated and installed in a ground potential case to form an air insulation type resistance device. The ground potential case containing a predetermined number of resistors has an inlet for outside air at the lower periphery and an outlet for discharging the outside air at the upper part, and is grounded by the inlet and outlet of the outside air. A neutral grounding resistance device characterized in that a flow path for outside air is formed in a potential case.

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