JPH06140264A - Current detector - Google Patents

Abstract

PURPOSE:To provide a current detector which is able to accurately detect the zero-phase current of a cable restraining a pseudo-output from being generated without offset adjustment. CONSTITUTION:A gap is provided to a nearly elliptical ring-shaped core 12, a magnetic sensor 4 is inserted into the gap, a magnetic field generated in the core 12 by a three-phase current flowing through cables 8, 9, and 10 which penetrate through the core 12 is measured by a detector 7 to detect the current, wherein the sectional area of the core 12 nearly in parallel with its major axis is set smaller than other sectional areas.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は電流検出、殊に三相交流
電線の零相電流の検出に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to current detection, and more particularly to zero-phase current detection in a three-phase AC line.

【０００２】[0002]

【従来の技術】現代社会に於いては、安定的な電力供給
が必要不可欠な要素となっており、これを確保すべく配
電システムの中に所定数の計測手段を具備せしめ配電線
管理を行うと云う重要な役割が電力の供給者に課されて
いる。2. Description of the Related Art In modern society, stable power supply is an indispensable element, and in order to secure this, the power distribution system is equipped with a predetermined number of measuring means to manage the distribution line. An important role is called the power supplier.

【０００３】従来より、配電線に対する電気絶縁性、或
いは耐電磁ノイズ性、防爆性に優れ、しかも小型軽量性
をも実現した光式零相電流検出器が注目され実用化され
つつある。図３は光式零相電流検出器の構成を示す図で
ある。同図に於いて１は被測定電路であって、該電路１
がほぼ中央を貫通するよう円形の環状コア２を配置する
ことによって前記電路１を流れる電流値に対応した磁界
Ｈが前記コア２内に発生する。この磁界Ｈを検出するた
め、予め前記コア２に形成したギャップ部３に、印加さ
れた磁界の大きさ即ち磁束密度の量に応じて光線の光量
を変化する光磁気センサ４を挿入すると共に該光磁気セ
ンサ４に光ファイバ５を介して光線を供給するための発
光部と光磁気センサ４からの出力光を光ファイバ６を介
して受光し電気信号に変換した後、該電気信号より前記
電路１に流れる電流値を求めるための制御部とを有する
計測装置７にて電路１を流れる電流値を検出するもので
ある。Conventionally, an optical zero-phase current detector, which is excellent in electrical insulation against a distribution line, electromagnetic noise resistance, and explosion proof, and is compact and lightweight, has been attracting attention and put into practical use. FIG. 3 is a diagram showing the configuration of the optical zero-phase current detector. In the figure, 1 is a circuit to be measured,
By arranging the circular annular core 2 so as to penetrate substantially the center, a magnetic field H corresponding to the value of the current flowing through the electric path 1 is generated in the core 2. In order to detect this magnetic field H, a magneto-optical sensor 4 that changes the light amount of a light beam according to the magnitude of the applied magnetic field, that is, the amount of magnetic flux density is inserted into the gap portion 3 formed in advance in the core 2, and A light emitting portion for supplying a light beam to the magneto-optical sensor 4 through the optical fiber 5 and output light from the magneto-optical sensor 4 are received through the optical fiber 6 and converted into an electric signal, and then the electric path is converted from the electric signal. The value of the current flowing through the electric circuit 1 is detected by the measuring device 7 having a control unit for obtaining the value of the current flowing through 1.

【０００４】更に、この原理を利用して三相交流電線を
流れる三相交流の零相電流を検出するため図４の如き構
成の光式零相電流検出器が提案されており、一列に並ん
だ３本の電路８、９及び１０には夫々三相交流のｕ相、
ｖ相及びｗ相の電流が流れているものとし、これら３本
の電路８、９及び１０が貫通するようトラック型の環状
コア１１を配置したもので、該コア１１のギャップには
図３と同様の光磁気センサ４が挿入されている。尚、こ
の電流検出器は、各電路が比較的離れて配設されている
送電経路に於いてはコアの実現が困難であるため、コア
が形成可能な大きさとなる開閉器近傍に設置するのが一
般的である。Further, in order to detect the zero-phase current of the three-phase alternating current flowing through the three-phase alternating current wire by utilizing this principle, an optical zero-phase current detector having a structure as shown in FIG. 4 has been proposed and arranged in a line. The three electric lines 8, 9 and 10 are u-phases of three-phase alternating current,
It is assumed that currents of v-phase and w-phase are flowing, and a track-type annular core 11 is arranged so that these three electric paths 8, 9 and 10 penetrate, and the gap of the core 11 is as shown in FIG. A similar magneto-optical sensor 4 is inserted. Since it is difficult to realize a core in a power transmission path in which the electric paths are arranged relatively distant from each other, this current detector is installed near the switch where the core can be formed. Is common.

【０００５】しかしながら、周知の通り、コアに発生す
る磁界は電路を流れる電流値によって変化するのはもち
ろん、電路とコアとの距離によっても変化するから、図
４に於いて両端に配置された電路８及び１０については
コアとの距離の条件はほぼ同等であるが、中央に配置さ
れた電路９は前記２本の電路と明らかに条件が異なり、
他の２本よりコア１１への影響が大きく、３本の電路
８、９及び１０に三相平衡電流を流した場合であっても
残留電流が存在するかの如き疑似出力が検出されるとい
う欠陥があった。However, as is well known, the magnetic field generated in the core varies depending not only on the value of the current flowing through the electric path but also on the distance between the electric path and the core. Therefore, the electric paths arranged at both ends in FIG. Regarding 8 and 10, the condition of the distance from the core is almost the same, but the condition of the electric path 9 arranged in the center is obviously different from the above two electric paths,
The influence on the core 11 is larger than the other two, and even if a three-phase balanced current is applied to the three electric paths 8, 9 and 10, a pseudo output as if there is a residual current is detected. There was a flaw.

【０００６】例えば、３本の電路を夫々正三角形の頂点
の位置に配列する或いは撚線とし、コアを円形にするこ
とでコアと各電路との距離の関係は同等となりこの欠点
を解決できるものの、実際には、配電線の開閉器の小型
化及び各電路間の絶縁を確実にすべく開閉器内へ導入す
る電路を開閉器の小型化に支障のない程度の間隙を隔し
て一列に配置するのが一般的であって、必然的にコアの
形状も小型化を損なわないようトラック型或いは比較的
偏平な略楕円形とすることが要求されている。For example, by arranging the three electric paths at the positions of the vertices of an equilateral triangle or forming a twisted wire and making the core circular, the relationship between the distance between the core and each electric path becomes equal, and this drawback can be solved. Actually, in order to downsize the switch of the distribution line and ensure the insulation between each electric line, the electric lines to be introduced into the switch should be arranged in a line with a gap that does not hinder the downsizing of the switch. In general, they are arranged, and inevitably, the shape of the core is required to be a track type or a relatively flat elliptical shape so as not to impair the miniaturization.

【０００７】又、図４の如き光式零相電流検出器に於い
て、前述の疑似出力分を打ち消すように光磁気センサ４
からの出力値を調整するオフセット設定機能を前記計測
部７に具備させてもよいが、実際にはその調整工程が極
めて煩雑であり、現場での設置、保守作業が容易ではな
いという問題点があった。Further, in the optical zero-phase current detector as shown in FIG. 4, the magneto-optical sensor 4 is arranged so as to cancel the above pseudo output.
Although the measuring unit 7 may be provided with an offset setting function for adjusting the output value from, the adjustment process is actually very complicated, and there is a problem that on-site installation and maintenance work is not easy. there were.

【０００８】[0008]

【発明の目的】本発明は上述した如き従来の電流検出器
の欠陥を除去するためになされたものであって、オフセ
ット調整なしに疑似出力の発生を抑圧し、高精度に被測
定電路の零相電流を検出すること可能な電流検出器を提
供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the defects of the conventional current detector as described above, and suppresses the generation of the pseudo output without adjusting the offset, and with a high accuracy, the zero of the measured electric circuit. It is an object to provide a current detector capable of detecting a phase current.

【０００９】[0009]

【発明の概要】上述の目的を達成するため本発明に係る
電流検出器は、略楕円形の環状コアにギャップを設ける
と共に該ギャップに磁気センサを挿入し、前記コアを貫
通する被測定電路を流れる三相交流電流によって前記コ
アに発生する磁界を測定することにより前記電流を検出
するものに於いて、前記コアの長軸方向とほぼ平行な部
分の断面積を他の部分のそれに比して小さくしたことに
より、疑似出力の発生を抑圧したものである。SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a current detector according to the present invention is provided with a gap in a substantially elliptical annular core, a magnetic sensor is inserted in the gap, and a measured electric circuit passing through the core is provided. In the one for detecting the current by measuring the magnetic field generated in the core by the flowing three-phase alternating current, the cross-sectional area of the portion substantially parallel to the long axis direction of the core is compared with that of other portions. By making it small, the generation of pseudo output is suppressed.

【００１０】[0010]

【実施例】以下、本発明を実施例を示す図面に基づいて
詳細に説明する。図１は本発明に係る光式零相電流検出
器の一実施例の構成を示す図であって、夫々三相交流の
ｕ相、ｖ相及びｗ相の電流が流れている３本の電路８、
９及び１０が貫通するようトラック型の環状コア１２を
配置し、コア１２のギャップに磁界の大きさに応じて光
線の光量を変化する光磁気センサ４を挿入し、該光磁気
センサ４を光ファイバ５及び６を介して計測装置７と結
合したものに於いて、前記トラック型の環状コア１２の
２つの弧状部を２本の直線状部に比して太く即ち断面積
が大きくなるよう構成したものである。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a diagram showing a configuration of an embodiment of an optical zero-phase current detector according to the present invention, in which three electric paths in which u-phase, v-phase, and w-phase currents of a three-phase alternating current flow, respectively. 8,
A track-shaped annular core 12 is arranged so that 9 and 10 penetrate therethrough, and a magneto-optical sensor 4 that changes the amount of light according to the magnitude of the magnetic field is inserted in the gap of the core 12, and the magneto-optical sensor 4 In the case of being connected to the measuring device 7 via the fibers 5 and 6, the two arc-shaped portions of the track-shaped annular core 12 are made thicker, that is, the cross-sectional area is larger than the two linear portions. It was done.

【００１１】コアに発生する磁界は電路を流れる電流値
によって変化するのはもちろん、電路とコアとの距離に
よっても変化するから、従来の如く断面積がすべて一定
なコアを用いた場合、例えば電路８或いは１０を流れる
電流によるコアへの影響は夫々図中左側或いは右側の弧
状部のみに及ぶのに対し、ほぼ中央に位置する電路９を
流れる電流によるそれは２本の直線状部の双方に比較的
広く及ぶことは明らかであり、電路に三相平衡電流を流
したにも拘わらず残留電流が存在するかの如き疑似出力
が検出されるという欠陥があったこと前述の通りであ
る。The magnetic field generated in the core varies depending not only on the value of current flowing through the electric path but also on the distance between the electric path and the core. The influence of the current flowing through 8 or 10 on the core extends only to the left or right side arcuate portion in the figure, respectively, whereas that due to the current flowing through the electric path 9 located at the center is compared to both of the two linear portions. It is obvious that the range is extremely wide, and as described above, there is a defect that a pseudo output is detected as if a residual current exists even though a three-phase balanced current is applied to the electric path.

【００１２】そこで、コアに発生する磁界はコアの断面
積によっても変化することに着目し、電路８或いは１０
を流れる電流による影響が少なかったコア両端の弧状部
について断面積を直線状部のそれに比して大きくなるよ
う構成したのである。この断面積の差異を適当な値、例
えば、図１の線路８、１０をコアの弧状部両端を結ぶ直
線上に配置する場合は断面積の比を概ね１：２に選択す
ればよい。Therefore, paying attention to the fact that the magnetic field generated in the core also changes depending on the cross-sectional area of the core, the electric circuit 8 or 10
The cross-sectional area of the arcuate portion at both ends of the core, which was less affected by the current flowing through the core, was made larger than that of the linear portion. This difference in cross-sectional area is set to an appropriate value, for example, when the lines 8 and 10 in FIG. 1 are arranged on a straight line connecting both ends of the arcuate portion of the core, the cross-sectional area ratio may be selected to be approximately 1: 2.

【００１３】図２は本発明に係る光式零相電流検出器の
第２の実施例を示す図であり、コア１３が比較的偏平な
即ち長軸と短軸の差異が大きい略楕円形状をしたもので
あって、コアの長軸とほぼ平行な部分の断面積を最小と
して曲率が大きくなるに従って断面積が漸増するよう構
成したものであり、図１と同等の動作をする。上述した
如きやや複雑な形状のコアであっても、予め型を作成し
ておくことにより何等格別の困難なしに成型することが
可能であり、又、電算機による磁気回路解析を行うこと
により試作による実験を繰り返すことなくコアの寸法を
決定することも可能である。FIG. 2 is a diagram showing a second embodiment of the optical zero-phase current detector according to the present invention, in which the core 13 has a relatively flat shape, that is, a substantially elliptical shape having a large difference between the major axis and the minor axis. It is configured such that the cross-sectional area gradually increases as the curvature increases with the cross-sectional area of the portion substantially parallel to the long axis of the core being the minimum, and operates in the same manner as in FIG. Even if the core has a slightly complicated shape as described above, it can be molded without any particular difficulty by creating a mold in advance.Also, by conducting a magnetic circuit analysis with a computer, a prototype is produced. It is also possible to determine the dimensions of the core without repeating the experiment according to.

【００１４】尚、以上本発明を光磁気センサを用いた光
式零相電流検出器を例として説明したが、本発明はこれ
のみに限定されるものではなく、コアをギャップなしの
閉リングとし、これにコイルを巻いてコアに発生する磁
界を抽出する等、他の磁気検出センサを用いたものであ
ってもよいこと明白である。Although the present invention has been described by taking the optical zero-phase current detector using the magneto-optical sensor as an example, the present invention is not limited to this, and the core may be a closed ring having no gap. It is obvious that another magnetic detection sensor may be used, such as winding a coil around this to extract the magnetic field generated in the core.

【００１５】[0015]

【発明の効果】本発明は、以上説明した如く構成するも
のであるから、環状のコアの形状を変更するのみで、格
別の調整なしに疑似出力の発生を抑圧し、高精度に被測
定電路の零相電流を検出すること可能な電流検出器を構
成する上で著しい効果を奏する。Since the present invention is configured as described above, it is possible to suppress the generation of pseudo output without special adjustment by simply changing the shape of the annular core and to accurately measure the electric circuit under test. It has a remarkable effect in constructing a current detector capable of detecting the zero-phase current.

【００１６】[0016]

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明に係る光式零相電流検出器の一実施例の
構成を示す図。FIG. 1 is a diagram showing the configuration of an embodiment of an optical zero-phase current detector according to the present invention.

【図２】本発明に係る光式零相電流検出器の第２の実施
例を示す図。FIG. 2 is a diagram showing a second embodiment of the optical zero-phase current detector according to the present invention.

【図３】従来の光式零相電流検出器の構成を示す図。FIG. 3 is a diagram showing a configuration of a conventional optical zero-phase current detector.

【図４】従来の光式零相電流検出器の構成を示す図。FIG. 4 is a diagram showing a configuration of a conventional optical zero-phase current detector.

【符号の説明】[Explanation of symbols]

４・・・光磁気センサ ５，６・・・光ファイバ ７・・・計測部 ８，９，１０・・・電路 １２，１３・・・コア 4 ... Magneto-optical sensor 5, 6 ... Optical fiber 7 ... Measuring unit 8, 9, 10 ... Electrical path 12, 13 ... Core

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】環状のコアを貫通する被測定電路を流れる
電流によって前記コアに発生する磁界を磁気センサにて
測定することにより前記電流を検出する電流検出器に於
いて、前記コアを略楕円形とし、その長軸とほぼ平行な
部分の断面積を他の部分のそれに比して小さくしたこと
を特徴とする電流検出器。1. A current detector for detecting a current by measuring a magnetic field generated in the core by a current flowing through an electric circuit to be measured passing through an annular core by a magnetic sensor to detect the current. A current detector characterized by having a shape and a cross-sectional area of a portion substantially parallel to its long axis made smaller than that of other portions. 【請求項２】前記コアの形状をトラック型とし、その直
線部分の断面積を弧状部分のそれに比して小さくしたこ
とを特徴とする請求項１記載の電流検出器。2. The current detector according to claim 1, wherein the shape of the core is a track type, and the cross-sectional area of the linear portion is smaller than that of the arc-shaped portion. 【請求項３】前記被測定電路が三相交流電線であって、
その零相電流を検出することを特徴とする請求項１或い
は請求項２記載の電流検出器。3. The measured electric circuit is a three-phase AC electric wire,
The current detector according to claim 1 or 2, wherein the zero-phase current is detected.