JPH08152448A - Zero-phase-current measuring circuit of three-phase alternating current - Google Patents
Zero-phase-current measuring circuit of three-phase alternating currentInfo
- Publication number
- JPH08152448A JPH08152448A JP6316068A JP31606894A JPH08152448A JP H08152448 A JPH08152448 A JP H08152448A JP 6316068 A JP6316068 A JP 6316068A JP 31606894 A JP31606894 A JP 31606894A JP H08152448 A JPH08152448 A JP H08152448A
- Authority
- JP
- Japan
- Prior art keywords
- phase
- current
- magnetic field
- zero
- photosensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004020 conductor Substances 0.000 claims abstract description 35
- 230000003287 optical effect Effects 0.000 claims description 20
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 8
- 238000005259 measurement Methods 0.000 abstract description 6
- 239000000126 substance Substances 0.000 abstract description 6
- 230000004907 flux Effects 0.000 abstract description 2
- 238000006243 chemical reaction Methods 0.000 description 5
- 239000013307 optical fiber Substances 0.000 description 4
- 238000004804 winding Methods 0.000 description 4
- 230000005674 electromagnetic induction Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000000696 magnetic material Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000008054 signal transmission Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Landscapes
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Transformers For Measuring Instruments (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光ＣＴを用いた、三相
交流回路の零相電流測定回路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zero-phase current measuring circuit for a three-phase AC circuit using an optical CT.
【０００２】[0002]
【従来の技術】従来の零相電流測定回路は、零相変流器
ＺＣＴ一台または変流器ＣＴを三台使用することによ
り、三相交流の零相電流を測定している。以下図５によ
りＺＣＴを使用した三相交流の零相電流測定回路を説明
する。図５（ａ）に示す回路おいて、三相一次電流ベク
トルを図５（ｂ）のようなＩa 、Ｉb 、Ｉc とし、二次
の巻数をＮとすると、負担抵抗Ｒg には各一次電流の１
／Ｎのベクトル和Ｉ2 が流れる。式で表すと式（１）で
表すことができる。 Ｉ2 ＝（Ｉa ＋Ｉb ＋Ｉc ）／Ｎ ・・・（１） ここで、式（１）の（Ｉa ＋Ｉb ＋Ｉc ）は対称座標法
でいう零相電流３Ｉ0 だから、Ｉ2 は式（２）のように
なる。 Ｉ2 ＝（３Ｉ0 ）／Ｎ ・・・（２） 即ち、Ｉ2 の読みを（Ｎ／３）倍することにより、零相
電流を測定できる。また、三相電流に零相分が含まれて
いないときは、二次側には電流は流れない。最近、電磁
無誘導性、電気絶縁性、化学的安定性等を特徴とした光
ＣＴにより、一線の電流を測定することが知らされてい
るが、三相交流の零相電流を測定するための回路は、知
られていない。2. Description of the Related Art A conventional zero-phase current measuring circuit measures a zero-phase current of a three-phase alternating current by using one zero-phase current transformer ZCT or three current transformers CT. A zero-phase current measuring circuit for three-phase AC using ZCT will be described below with reference to FIG. In the circuit shown in FIG. 5A, assuming that the three-phase primary current vector is I a , I b , and I c as shown in FIG. 5B and the number of secondary turns is N, the burden resistance R g is 1 for each primary current
The vector sum I 2 of / N flows. When represented by a formula, it can be represented by formula (1). I 2 = (I a + I b + I c ) / N (1) Here, (I a + I b + I c ) in the equation (1) is the zero-phase current 3I 0 in the symmetrical coordinate method, so I 2 Becomes like the formula (2). I 2 = (3I 0 ) / N (2) That is, the zero-phase current can be measured by multiplying the reading of I 2 by (N / 3). When the three-phase current does not include the zero-phase component, no current flows on the secondary side. Recently, it has been known to measure a one-line current by optical CT, which is characterized by electromagnetic non-inductivity, electrical insulation, chemical stability, etc. The circuit is unknown.
【０００３】[0003]
【発明が解決しようとする課題】ところで、三相電流に
零相分が含まれていないとき、二次側には電流は流れな
いはずであるが、上記ＺＣＴによる計測では、若干の電
流が流れる。これは、一次導体と鉄心の幾何学的配置、
鉄心特性の不均一性により出力が発生するためである。
この二次側に流れる電流が残留電流である。残留電流を
少なく抑えるには、鉄心の材質を高透磁率のニッケル鋼
板とし、二次巻線を多くする（あまり多くすると零相電
流のレベルが低くなる）ことが必要である。また、二次
側の測定回路は電線のため、シールド等の対策を施して
一次回路をはじめその他の回路からの電磁誘導作用を防
いだり、鉄心と二次巻線を一次巻線に対して絶縁耐力を
もたせるとともに、銅・鉄・絶縁材料の酸化防止等の化
学的安定性を考慮して製作する必要がある。そこで、本
発明の目的は、簡単な装置構成で、残留電流の発生を抑
えるとともに、電磁誘導作用を受けず、高い絶縁耐力を
もち、化学的安定性に優れた、三相交流の零相電流測定
回路を提供することにある。By the way, when the three-phase current does not include the zero-phase component, the current should not flow to the secondary side, but in the measurement by the ZCT, some current flows. . This is the geometric arrangement of the primary conductor and the iron core,
This is because the output is generated due to the non-uniformity of the iron core characteristics.
The current flowing on the secondary side is the residual current. In order to suppress the residual current to a low level, it is necessary to use a high-permeability nickel steel plate as the material of the iron core and increase the number of secondary windings (if the amount is too large, the zero-phase current level decreases). Also, because the secondary side measurement circuit is an electric wire, measures such as shielding are taken to prevent electromagnetic induction from the primary circuit and other circuits, and the iron core and secondary winding are insulated from the primary winding. It is necessary to make it proof and to consider the chemical stability such as oxidation prevention of copper, iron and insulating material. Therefore, the object of the present invention is to suppress the generation of residual current with a simple device configuration, not to be affected by electromagnetic induction, have high dielectric strength, and have excellent chemical stability. It is to provide a measurement circuit.
【０００４】[0004]
【課題を解決するための手段】本発明は、軸中心線が正
三角形に配設された三相交流回路の導体と、これら導体
の正三角形の中心に、これら導体に流れる電流が作る磁
界に対して９０度の角度がもたれる方向を向きかつソー
スとドレインを結ぶ中心線がこれら導体と平行になるよ
うに配置することを、特徴とするものである。DISCLOSURE OF THE INVENTION The present invention is directed to conductors of a three-phase AC circuit whose axial center lines are arranged in an equilateral triangle, and a magnetic field generated by a current flowing through these conductors at the center of the equilateral triangles of these conductors. It is characterized by arranging so that the center line connecting the source and the drain is parallel to these conductors and facing the direction in which an angle of 90 degrees is given.
【０００５】[0005]
【作用】このようにすると、光センサーが配置される点
の磁界は、三相交流回路に流れる電流Ｉa 、Ｉb 、Ｉc
からの距離が等しいために、残留電流を抑えられると同
時に、一つの光センサーでＩa 、Ｉb 、Ｉc の和、即ち
（Ｉa ＋Ｉb ＋Ｉc ）＝３Ｉ0 を測定することができ
る。光ＣＴは、光センサーと信号伝送路に光ファイバー
を使用するので、ノイズ等の電磁誘導作用を受けず、ま
た高い絶縁性と化学的安定性確保できる。SUMMARY OF] Thus, the magnetic field of a point light sensor is disposed, the current I a flowing through the three-phase alternating current circuit, I b, I c
Since the distance from is equal, the residual current can be suppressed, and at the same time, the sum of I a , I b , and I c , that is, (I a + I b + I c ) = 3I 0 can be measured by one photosensor. . Since the optical CT uses an optical sensor and an optical fiber for a signal transmission path, it is not affected by an electromagnetic induction effect such as noise, and high insulation and chemical stability can be secured.
【０００６】[0006]
【実施例】先ず、光ＣＴは、どのようにして導体を流れ
る電流を計測しているか、説明する。導体に電流が流れ
ることによって生じる磁界の強さは、電流の大きさに比
例し、電流からの距離に反比例すると知られている。ア
ンペアの周回積分の法則によれば、電流Ｉが作る磁界Ｈ
は、電流Ｉと距離ｒ上の円周上ではどこでも磁界の大き
さは一定である。式で表すと式（３）のようになる。 電流Ｉ＝（２πｒ）Ｈ ・・・（３） ここで、距離ｒは電流センサーを設置したときに決まる
値であるから、磁界Ｈを光ファイバー磁界センサーによ
り計測すれば、電流Ｉを求めることができる。即ち、光
ＣＴのセンサーは、磁界を測定しているが、光電変換部
でこの磁界の値と設置したときの距離を演算して、電流
を求めている。これが、光ＣＴの動作原理である。EXAMPLES First, how the optical CT measures the current flowing through the conductor will be described. It is known that the strength of a magnetic field generated by a current flowing through a conductor is proportional to the magnitude of the current and inversely proportional to the distance from the current. According to Ampere's law of circular integration, the magnetic field H created by the current I
Has a constant magnitude of magnetic field everywhere on the circumference of the current I and the distance r. When expressed by a formula, it becomes like a formula (3). Current I = (2πr) H (3) Here, since the distance r is a value determined when the current sensor is installed, the current I can be obtained by measuring the magnetic field H with the optical fiber magnetic field sensor. . That is, the sensor of the optical CT measures the magnetic field, but the photoelectric conversion unit calculates the value of this magnetic field and the distance when it is installed to obtain the current. This is the operating principle of optical CT.
【０００７】また、三本の導体を図４に示すように、任
意の位置に配設した場合、点ｘでの磁界Ｈを考える。そ
れぞれ導体には三相交流の電流Ｉa 、Ｉb 、Ｉc が流れ
ている。Ｉa が流れることによって点ｘに生ずる磁界Ｈ
a は、Ｉa とｘの距離をｒaとすると Ｈa ＝Ｉa ／（２πｒa ） ・・・（４） となる。Ｉb が流れることによって点ｘに生ずる磁界Ｈ
b は、Ｉb とｘの距離をｒb とすると Ｈb ＝Ｉb ／（２πｒb ） ・・・（５） となる。Ｉc が流れることによって点ｘに生ずる磁界Ｈ
c は、Ｉc とｘの距離をｒc とすると Ｈc ＝Ｉc ／（２πｒc ） ・・・（６） となる。点ｘでの磁界Ｈは、 Ｈ＝Ｈa ＋Ｈb ＋Ｈc ・・・（７） ＝ Ｉa ／（２πｒa ） ＋Ｉb ／（２πｒb ） ＋Ｉc ／（２πｒc ） ・・・（８） となる。When the three conductors are arranged at arbitrary positions as shown in FIG. 4, the magnetic field H at the point x will be considered. Three-phase alternating currents I a , I b , and I c are flowing in the conductors. Magnetic field H generated at point x by the flow of I a
a becomes H a = I a / (2πr a ) ... (4), where r a is the distance between I a and x. Magnetic field H generated at point x by flowing I b
b is H b = I b / (2πr b ) ... (5) where r b is the distance between I b and x. Magnetic field H generated at point x by the flow of I c
c is a and the distance I c and x and r c H c = I c / (2πr c) ··· (6). The magnetic field H at point x, H = H a + H b + H c ··· (7) = I a / (2πr a) + I b / (2πr b) + I c / (2πr c) ··· (8) Becomes
【０００８】以下本発明の一実施例を図１と図２を参照
して説明する。図１は、導体の斜め方向から見た図で、
図２は、導体の軸線に垂直な断面図である。三本の導体
配置は互いに平行にかつそれらの軸線が正三角形に配設
されていて、その中心に光センサーが設けてある。光セ
ンサーの据え付け方向は、導体に流れる電流が作る磁束
と９０度の角度がもたれる方向を向き、なおかつソース
とドレインを結ぶ中心線が導体と平行になるように光セ
ンサーを配置する。即ち、導体の軸と光センサーの軸を
同じ向きにする。光電変換部は、光センサーからの光信
号を電気信号に変換している。光電変換部と光センサー
は光ファイバーケーブルにより信号伝送している。図４
で示される三本の導体を、正三角形に配置し、光センサ
ーを導体の中心に設け、この距離を式（９）の如くｒと
すれば、導体の中心点の磁界Ｈは式（８）から式（１
０）のようになる。 ｒ＝ｒa ＝ｒb ＝ｒc ・・・（９） Ｈ＝（Ｉa ＋Ｉb ＋Ｉc ）／（２πｒ）・・・（１０） このように、零相電流に比例した磁界を得ることができ
る。この磁界を光センサーで受け取り、光ファイバーに
より光電変換部へ信号伝送する。光電変換部では、光信
号から電気信号に変換するとともに、磁界と距離から零
相電流をを算出している。An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a view of the conductor as viewed from an oblique direction,
FIG. 2 is a sectional view perpendicular to the axis of the conductor. The three conductor arrangements are arranged parallel to each other and their axes are equilateral triangles, and the optical sensor is provided at the center thereof. The optical sensor is installed so that the magnetic flux generated by the current flowing through the conductor is oriented at an angle of 90 degrees, and the optical sensor is arranged such that the center line connecting the source and the drain is parallel to the conductor. That is, the axis of the conductor and the axis of the optical sensor are oriented in the same direction. The photoelectric conversion unit converts an optical signal from the optical sensor into an electric signal. The photoelectric conversion unit and the optical sensor transmit signals via an optical fiber cable. FIG.
If three conductors shown by are arranged in an equilateral triangle, the optical sensor is provided at the center of the conductor, and this distance is r as shown in equation (9), the magnetic field H at the center point of the conductor is given by equation (8). From the formula (1
It becomes like 0). r = r a = r b = r c (9) H = (I a + I b + I c ) / (2πr) (10) Thus, obtaining a magnetic field proportional to the zero-phase current You can This magnetic field is received by an optical sensor, and a signal is transmitted to a photoelectric conversion unit by an optical fiber. The photoelectric conversion unit converts an optical signal into an electric signal and calculates a zero-phase current from the magnetic field and the distance.
【０００９】以上の結果より、電流Ｉa 、Ｉb 、Ｉc と
中心点の磁気的結合は、鉄心等の磁性体を使用していな
いので、製作時に生じる鉄心の据え付け誤差や、磁気特
性のばらつきの影響がなく、また光センサーは非磁性体
材料のため、電流が作る磁界を乱すことがないため、残
留電流を抑え、誤差の少ない測定をすることができる。From the above results, the magnetic coupling between the currents I a , I b , and I c and the center point does not use a magnetic material such as an iron core. There is no influence of variations, and since the optical sensor is a non-magnetic material, it does not disturb the magnetic field created by the current. Therefore, residual current can be suppressed and measurement with less error can be performed.
【００１０】また、図３のように、導体の軸を三角錘の
形に配設した場合であっても、電流Ｉa 、Ｉb 、Ｉc か
らの距離が等しいため零相電流に比例した磁界を得るこ
とができるため、この磁界と距離から零相電流の算出は
可能である。Even when the conductor shafts are arranged in the shape of a triangular pyramid as shown in FIG. 3, since the distances from the currents I a , I b , and I c are equal, they are proportional to the zero-phase current. Since the magnetic field can be obtained, the zero-phase current can be calculated from this magnetic field and the distance.
【００１１】[0011]
【発明の効果】以上述べてきたように、本発明によれ
ば、極めて容易な導体配置、光センサー配置で三相回路
の零相電流を誤りなく測定できるとともに、従来の零相
ＣＴやＣＴ三台に比べ小型軽量化され、実用的には極め
て有効である。As described above, according to the present invention, the zero-phase current of a three-phase circuit can be measured without error with an extremely easy conductor arrangement and optical sensor arrangement, and the conventional zero-phase CT or CT It is smaller and lighter than a stand, and is extremely effective in practice.
【図１】本発明の実施例の零相電流回路を、導体の斜め
方向からみた斜視図である。FIG. 1 is a perspective view of a zero-phase current circuit according to an embodiment of the present invention as seen from an oblique direction of a conductor.
【図２】本発明の実施例の零相電流回路を、導体の軸方
向からみた平面図である。FIG. 2 is a plan view of the zero-phase current circuit according to the embodiment of the present invention as viewed from the axial direction of the conductor.
【図３】本発明の実施例の零相電流回路を、導体の軸を
三角錘の形に配設した場合の斜視図である。FIG. 3 is a perspective view of the zero-phase current circuit according to the embodiment of the present invention in which the shaft of the conductor is arranged in the shape of a triangular pyramid.
【図４】三本の導体を任意の位置に配設した状態を、導
体の軸方向からみた平面図である。FIG. 4 is a plan view of a state in which three conductors are arranged at arbitrary positions as viewed from the axial direction of the conductors.
【図５】従来の零相電圧検出回路を示す回路図である。FIG. 5 is a circuit diagram showing a conventional zero-phase voltage detection circuit.
Ｉa Ａ相電流ベクトル Ｉb Ｂ相電流ベクトル Ｉc Ｃ相電流ベクトル Ｉ2 Ｉa とＩb とＩc のベクトル和 Ｎ 零相変流器の二次巻数 Ｒg 負担抵抗 ｒ 導体とセンサーとの距離I a A-phase current vector I b B-phase current vector I c C-phase current vector I 2 Ia and vector sum of I b and I c N Secondary winding number of zero-phase current transformer R g Burden resistance r Conductor and sensor The distance
Claims (1)
流回路の導体と、これら導体の正三角形の中心に、これ
ら導体に流れる電流が作る磁界に対して９０度の角度が
もたれる方向を向きかつソースとドレインを結ぶ中心線
がこれら導体と平行になるように配置された光ＣＴのセ
ンサーと、からなる三相交流の零相電流測定回路。1. A conductor of a three-phase AC circuit whose axial center line is arranged in an equilateral triangle, and the center of the equilateral triangle of these conductors has an angle of 90 degrees with respect to a magnetic field generated by a current flowing through these conductors. A zero-phase current measuring circuit for three-phase alternating current, which comprises an optical CT sensor that is oriented so that the center line connecting the source and drain is parallel to these conductors.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6316068A JPH08152448A (en) | 1994-11-28 | 1994-11-28 | Zero-phase-current measuring circuit of three-phase alternating current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6316068A JPH08152448A (en) | 1994-11-28 | 1994-11-28 | Zero-phase-current measuring circuit of three-phase alternating current |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08152448A true JPH08152448A (en) | 1996-06-11 |
Family
ID=18072912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6316068A Pending JPH08152448A (en) | 1994-11-28 | 1994-11-28 | Zero-phase-current measuring circuit of three-phase alternating current |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08152448A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE112017001954T5 (en) | 2016-05-16 | 2019-01-03 | Hitachi Automotive Systems, Ltd. | Current detection device and power conversion device equipped therewith |
| JP2022021850A (en) * | 2020-07-22 | 2022-02-03 | 株式会社Soken | Current sensor |
-
1994
- 1994-11-28 JP JP6316068A patent/JPH08152448A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE112017001954T5 (en) | 2016-05-16 | 2019-01-03 | Hitachi Automotive Systems, Ltd. | Current detection device and power conversion device equipped therewith |
| US10564187B2 (en) | 2016-05-16 | 2020-02-18 | Hitachi Automotive Systems, Ltd. | Current detection device including a current sensor to detect magnetic field vectors |
| JP2022021850A (en) * | 2020-07-22 | 2022-02-03 | 株式会社Soken | Current sensor |
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