JP4354898B2 - Magnetic shield structure for AC power single wire cable - Google Patents
Magnetic shield structure for AC power single wire cable Download PDFInfo
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- JP4354898B2 JP4354898B2 JP2004323109A JP2004323109A JP4354898B2 JP 4354898 B2 JP4354898 B2 JP 4354898B2 JP 2004323109 A JP2004323109 A JP 2004323109A JP 2004323109 A JP2004323109 A JP 2004323109A JP 4354898 B2 JP4354898 B2 JP 4354898B2
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Description
本発明は、交流電力ケーブルから発生する磁気ノイズを遮蔽する磁気シールド構造に関するものである。 The present invention relates to a magnetic shield structure that shields magnetic noise generated from an AC power cable.
電力ケーブルの回りには電流により磁場が発生するが、ケーブルが磁場の被曝を気にする場所から遠く離れている場合は、磁場の距離減衰が期待できるためにそれほど重大な問題はない。しかし近年、ケーブルの地中埋設が実施されることが多くなり、しかもその埋設深さは浅くなる傾向にある。また、電力送電の各相のケーブルが近接していたり、撚り線構造となっていたりする場合は磁場の距離減衰が大きいので問題は少ないが、ジョイント部では、各相のケーブルが離れて存在する場合があり、ここからの磁場が問題となることがある。ケーブル間の距離が大きくなるほど、磁場の距離減衰が小さくなるからである。さらに、最近は磁場の人体への影響が懸念され始めており、許容される磁場の強さも小さくなる傾向にある。 A magnetic field is generated by the current around the power cable. However, when the cable is far away from the place where the exposure to the magnetic field is concerned, there is no serious problem because the distance attenuation of the magnetic field can be expected. In recent years, however, cables are often buried underground, and the depth of the cables tends to be shallow. In addition, if the cables of each phase of power transmission are close or have a stranded structure, there is little problem because the distance attenuation of the magnetic field is large. In some cases, magnetic fields from here can be a problem. This is because the distance attenuation of the magnetic field decreases as the distance between the cables increases. Furthermore, recently, there is a concern about the influence of the magnetic field on the human body, and the allowable strength of the magnetic field tends to decrease.
電力ケーブルからの磁場をシールドする方法のひとつとして、ケーブル内の心線が電磁鋼板と電磁軟鉄のテープで覆われた構造を持つ磁気遮蔽ケーブル（特許文献１）が提案されている。そこではケーブルからの磁場漏洩を小さくすることを目的としている。また、電源ケーブルを電磁鋼板で囲う磁気シールド用配管（特許文献２、特許文献３）も提案されている。さらに、ケーブル群を磁性体で囲うことを特徴とする磁気シールドピット（特許文献４）も提案されている。
上記の特許文献１〜３の特徴は、電流が流れる導体を同心円状に磁性体で覆うことで磁気シールドするものである。しかしながらこのような構成では、磁気シールド効果が十分に得られないという問題があった。また単線ケーブル同士の間隔が大きくなってくると、特許文献４の技術を用いても磁気シールド効果が不足する場合がある。
以上のように交流ケーブルの磁場の磁気シールドについて、特にケーブルの間隔が開いた場合には、シールド効果を得るための技術的な確立はなされていない。本発明はこのような課題に対して優れた磁気シールド性能を持つ磁気シールド構造を提案することを目的としている。
The features of the
As described above, regarding the magnetic shield of the magnetic field of the AC cable, especially when the distance between the cables is wide, technical establishment for obtaining the shielding effect has not been made. An object of the present invention is to propose a magnetic shield structure having excellent magnetic shielding performance against such problems.
本発明は、上記のように単線ケーブル同士の間隔が開いているときに、ケーブル１本毎を磁気シールドし、全体として磁場漏洩を遮蔽しようとするものである。
本発明の最大の特徴は、１本のケーブルだけを、欠落部を設けた筒状の磁性体で包囲することである。ケーブルを磁性体で、欠落部なしに完全に包囲しても、磁気シールド効果はまったく得られない。それは、以下の理由による。電流源を囲うように磁場要素を積分すると、その積分値は内部の電流に等しくなることはマックスウェルの方程式が教えるところである。電流が流れている１本のケーブルを磁性体で囲ったときは、内部の電流は有限の値であるから、磁場要素の積分も有限の値になる。従って、包囲している磁性体からその電流に応じた磁場が発生することになる。すなわち、原理的にシールドすることはできない。
しかしながら、磁性体にスリット状の欠落部を設けることによって、欠落部を設けた方向と反対側は、漏洩する磁場を小さくすることができることがわかった。
In the present invention, when the distance between the single-wire cables is open as described above, each cable is magnetically shielded so as to shield magnetic field leakage as a whole.
The greatest feature of the present invention is that only one cable is surrounded by a cylindrical magnetic body provided with a missing portion. Even if the cable is completely surrounded by a magnetic material without a missing portion, no magnetic shielding effect can be obtained. The reason is as follows. Maxwell's equations teach that integrating a magnetic field element around a current source results in an integral value equal to the internal current. When a single cable carrying a current is surrounded by a magnetic material, the internal current has a finite value, so the integral of the magnetic field element also has a finite value. Therefore, a magnetic field corresponding to the current is generated from the surrounding magnetic body. That is, it cannot be shielded in principle.
However, it has been found that by providing a slit-like missing portion in the magnetic body, the leakage magnetic field can be reduced on the side opposite to the direction in which the missing portion is provided.
本発明の磁気シールド構造を用いることによって、電力ケーブルからの不要な磁場を効率よく遮蔽することができる。 By using the magnetic shield structure of the present invention, an unnecessary magnetic field from the power cable can be efficiently shielded.
本発明は、間隔が開いた単線ケーブル全体を磁気シールドする交流電力単線ケーブル用磁気シールド構造であって、前記単線ケーブルが挿入される筒状体は方向性電磁鋼板からなり、かつ断面形状が円又は多角形であり、該筒状体の軸に垂直な断面の周上の一部に欠落部を設け、その欠落部が筒状体表面に軸方向にスリット状に存在し、その磁化容易方向が筒状体の周方向に向くようにして、単線ケーブル毎に磁気シールドしたことを特徴とする交流電力単線ケーブル用磁気シールド構造である。胴体の軸方向にスリット状の欠落部を作ることによって、磁場分布を変化させることができる。欠落部のある側の磁場は大きくなるので、磁場を小さくしたい方向には、欠落部のない面を配置し磁気シールドすることができる。欠落部の大きさは状況によって変化させることができ、これを特定するものではない。以上の形状の例を図１に示す。図１（ａ）は断面形状が円の筒状体の例を示し、同図（ｂ）は断面形状が矩形の筒状体の例を示しており、いずれも胴部の軸方向にスリット状の欠落部を形成している。 The present invention is a magnetic shield structure for an AC power single-wire cable that magnetically shields the entire single-wire cable with an interval, wherein the cylindrical body into which the single-wire cable is inserted is made of a directional electromagnetic steel sheet and has a circular cross-sectional shape or a polygon, the lack penetration point provided on part of the circumference of the cross section perpendicular to the axis of the cylindrical body, there axially slit shape is cylindrical surface thereof missing portion, the easy magnetization The magnetic shield structure for an AC power single-wire cable is characterized in that each single-wire cable is magnetically shielded such that the direction is directed to the circumferential direction of the cylindrical body . The magnetic field distribution can be changed by creating a slit-like missing portion in the axial direction of the trunk. Since the magnetic field on the side with the missing portion becomes larger, a surface without the missing portion can be arranged and magnetically shielded in the direction in which the magnetic field is desired to be reduced. The size of the missing portion can be varied depending on the situation, it name intended to identify it. Figure 1 shows examples of the shape of the following. 1 (a) shows an example of a cylinder with a cross-sectional shape circular, FIG. (B) is a cross-sectional shape shows an example of a rectangular tubular body, both slit-shaped in the axial direction of the barrel The missing part is formed.
軟磁性体としては、鉄系の軟磁性材料が加工もしやすく優れているが、特に電磁鋼板を用いることによって、磁気シールド性能は格段に上昇する。さらに、方向性電磁鋼板を用いてその磁化容易方向（圧延方向）を筒の胴体の周方向に一致させると、さらに磁気シールド性能は向上する。
このような磁気シールド構造を適用した電力ケーブル用配管は、洞道などの狭い場所にも配置することができる。
As the soft magnetic material, an iron-based soft magnetic material is easy to process and is excellent, but the magnetic shielding performance is remarkably improved by using an electromagnetic steel sheet in particular. Furthermore, when the direction of easy magnetization (rolling direction) is made to coincide with the circumferential direction of the cylinder body using a grain-oriented electrical steel sheet, the magnetic shielding performance is further improved.
The power cable piping to which such a magnetic shield structure is applied can be arranged in a narrow place such as a cave.
本発明の実施例を示す。
胴体に幅３５ｍｍのスリットを設けた内径２００ｍｍ、外形２２０ｍｍ、長さ１ｍの円筒シールド体を無方向性電磁鋼板および方向性電磁鋼板で作製した。比較のためにスリットのない同じサイズの円筒シールド体も無方向性電磁鋼板で作製した。３０ｍｍφの３相ケーブルのうち１本だけを円筒の中に通した。ケーブルと円筒の中心は同じになるように配置した。他の２本のケーブルからの磁場の影響をなくすため、それらは試験するケーブルから約５ｍ離して設置した。１本のケーブルに４００Ａが流れるように５０Ｈｚ、３相の送電をし、電流中心から半径方向の実効値磁場の変化を測定した。本発明（スリットの反対側）、比較例およびシールド体のない場合について、半径方向の磁場の変化を図２に示す。
The Example of this invention is shown.
A cylindrical shield body having an inner diameter of 200 mm, an outer diameter of 220 mm, and a length of 1 m provided with a slit having a width of 35 mm on the body was made of a non-oriented electrical steel sheet and a directional electrical steel sheet. For comparison, a cylindrical shield body of the same size without slits was also made of a non-oriented electrical steel sheet. Only one of the 30 mmφ three-phase cables was passed through the cylinder. The cable and the center of the cylinder were arranged to be the same. In order to eliminate the influence of the magnetic field from the other two cables, they were placed about 5 m away from the cable to be tested. Three-phase power transmission was performed at 50 Hz so that 400 A would flow through one cable, and the change in the effective magnetic field in the radial direction from the current center was measured. FIG. 2 shows the change in the magnetic field in the radial direction for the present invention (opposite side of the slit), the comparative example, and the case without the shield body.
図２において、（Ａ）は本発明を無方向性電磁鋼板で構成した場合、（Ｂ）は本発明を方向性電磁鋼板で構成した場合、（Ｃ）は比較例のスリットのない円筒形シールド体、（Ｄ）はシールド体を設置しない場合を、それぞれ示している。図２から本発明の（Ａ）（Ｂ）の場合が比較例の（Ｃ）（Ｄ）に比較して、磁場がシールドされていること、特に（Ｂ）の方向性電磁鋼板を用いた例が最も有効であることが分かる。 In FIG. 2, (A) is a non-oriented electrical steel sheet of the present invention, (B) is a non-oriented electrical steel sheet of the present invention, (C) is a cylindrical shield without slits of a comparative example. The body, (D) shows the case where the shield body is not installed. FIG. 2 shows that the magnetic field is shielded in the case of (A) and (B) of the present invention compared to (C) and (D) of the comparative example, in particular, an example using the grain-oriented electrical steel sheet of ( B ). Is the most effective.
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| Application Number | Priority Date | Filing Date | Title |
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| JP2004323109A JP4354898B2 (en) | 2004-11-08 | 2004-11-08 | Magnetic shield structure for AC power single wire cable |
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| JP2004323109A JP4354898B2 (en) | 2004-11-08 | 2004-11-08 | Magnetic shield structure for AC power single wire cable |
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| JP2006135116A JP2006135116A (en) | 2006-05-25 |
| JP4354898B2 true JP4354898B2 (en) | 2009-10-28 |
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| JP5558923B2 (en) * | 2010-05-28 | 2014-07-23 | 株式会社竹中工務店 | Magnetic shield body and method of adjusting relative permeability of magnetic shield body |
| JP6417214B2 (en) * | 2014-12-26 | 2018-10-31 | 川崎重工業株式会社 | Magnetic shielding structure for railway vehicles |
| JP6628404B2 (en) * | 2016-01-31 | 2020-01-08 | 鹿島建設株式会社 | Shaking type open magnetic shield structure |
| JP6599258B2 (en) * | 2016-01-31 | 2019-10-30 | 鹿島建設株式会社 | Shaking type open magnetic shield structure |
| KR102672743B1 (en) * | 2020-09-10 | 2024-06-07 | 한국전력공사 | Structure for shielding magnetic field having dissimilar composite material |
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| JP2003133780A (en) * | 2001-10-24 | 2003-05-09 | Kitagawa Ind Co Ltd | Noise absorbing device |
| JP2003258478A (en) * | 2002-02-28 | 2003-09-12 | Fujita Corp | Magnetic shielding structure |
| JP2004170091A (en) * | 2002-11-15 | 2004-06-17 | Aichi Micro Intelligent Corp | Current sensor |
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