JP3725408B2

JP3725408B2 - Low wind pressure insulated wire

Info

Publication number: JP3725408B2
Application number: JP2000240346A
Authority: JP
Inventors: 鉄男松本; 栄二白松; 直志菊池; 均竹内; 俊朗松村
Original assignee: THE FURUKAW ELECTRIC CO., LTD.; Kansai Electric Power Co Inc
Current assignee: THE FURUKAW ELECTRIC CO., LTD.; Kansai Electric Power Co Inc
Priority date: 1999-08-09
Filing date: 2000-08-08
Publication date: 2005-12-14
Anticipated expiration: 2020-08-08
Also published as: JP2001118434A

Description

【０００１】
【発明の属する技術分野】
本発明は、架空布設される低風圧絶縁電線及び難着雪性能を有する低風圧絶縁電線に関するものである。
【０００２】
【従来の技術】
架空配電線には一般に、銅又はアルミ導体に、ポリ塩化ビニル、ポリエチレン又は架橋ポリエチレン等の絶縁被覆（シースを含む）を施した絶縁電線が用いられている。従来の絶縁電線は、断面円形で、外周面が平滑であり、風圧を低減する対策は特にとられていなかった。
【０００３】
一方、電線の風圧荷重を低減する一つの手段として、特開平３−７４００９号公報には、電線の外周面に周方向に間隔をおいて多数の山部とそれらの山部に挟まれた多数の谷部を設けるとよいことが開示されている。一般に、表面に凹凸のない通常の絶縁電線を風の中に風向きに対し直角においた場合、図３（イ）に示すように空気の流れの剥離点Ｐが絶縁電線の風上側に生じ、絶縁電線の風下側に大きな後流領域ができるため風圧が高くなる。これに対し、絶縁電線の外周面に多数の凹凸を設けた場合は、図３（ロ）に示すように凹凸の存在によりＰ点で剥離した空気の流れがＱ点で再付着するような現象が生じ、後流領域が小さくなるため、風圧が低くなると考えられている。このことは実験によっても確かめられている。
【０００４】
【発明が解決しようとする課題】
しかしながら従来の風圧低減手段は、架空配電線のような外径が例えば９〜40mm程度の絶縁電線に適用した場合に、実用的な風速域（40ｍ／ｓ：「電気設備の技術基準」の架空電線路の設計条件甲種）で十分な風圧低減効果が得られないという問題があった。
また、風圧荷重低減効果が得られる電線としても、降雪時には電線表面に雪が付着するために、風圧荷重低減効果が得られない場合がある。
【０００５】
本発明の第一の目的は、上記のような問題を解決し、実用的な風速域で風圧荷重の小さい低風圧絶縁電線を提供することにある。
本発明の第二の目的は、さらに難着雪性能を有する低風圧絶縁電線を提供することにある。
【０００６】
【課題を解決するための手段】
上記第一の目的を達成するため本発明は、導体の外周に絶縁被覆を設けた架空布設される絶縁電線において、前記絶縁被覆の外周面に周方向に所定の間隔をおいて多数の山部とそれらの山部に挟まれた多数の谷部を設け、前記山部を外凸の曲面、前記谷部を外凹の曲面とし、かつ山部の曲面と谷部の曲面は滑らかに連なるものとし、谷部の内接円の半径をｒ、山部の高さをｈ（谷部の深さと同じ）、隣り合う山部の開き角をθ（隣り合う谷部の間の開き角と同じ）としたとき、ｒが4.5mm〜20mm、θが10°〜22.5°、ｈ／ｒが0.05〜0.2の範囲にあることを特徴とするものである。
【０００７】
また上記第二の目的を達成するため本発明は、上記のような低風圧絶縁電線において、山部と谷部を電線長手方向に直線状に設け、山部の外接円の半径をＲとしたとき、ｈ≧0.5 ×Ｒ×sin(θ／２) なる関係にあることを特徴とするものである。
このようにすると、電線表面に雪が付着しにくい難着雪効果も得ることができる。
【０００８】
【発明の実施の形態】
以下、本発明の実施形態を図面を参照して詳細に説明する。
図１は本発明による絶縁電線の一実施形態を示す。図において、１は導体、２は絶縁被覆（シースを含む）、３は絶縁被覆の外周面に形成された山部、４は山部３の間の谷部である。各山部３は丸みのある外凸の曲面とし、各谷部４は丸みのある外凹の曲面とし、山部３の曲面と谷部４の曲面は滑らかに連なっている（例えば山部３の曲面と谷部４の曲面が共通接線で連なっている）。また山部３と谷部４は、電線長手方向に直線状又はらせん状に形成されている。
【０００９】
そしてこの絶縁電線の特徴は、谷部３の内接円の半径をｒ、山部３の高さをｈ、隣り合う山部３の間の開き角をθとしたとき、ｒが4.5 mm〜20mm、θが10°〜22.5°、ｈ／ｒが0.05〜0.2 の範囲に設定されていることである。なおｒの範囲は、一般的に使用される架空配電用の 600Ｖ〜33ｋＶクラスの絶縁電線の半径に対応している。
【００１０】
このような範囲で風圧低減効果が得られることは次のような検討結果から見いだされたものである。
電線等の空力特性は一般に、抗力係数Ｃd とレイノルズ数Ｒe との関係で評価される。レイノルズ数Ｒe は次式で表される。
【００１１】
【数１】

【００１２】
図２に、図１の形状の絶縁電線について抗力係数Ｃd とレイノルズ数Ｒe の関係を測定した結果を示す。このデータによると例えばレイノルズ数Ｒe ＝30000 で抗力係数Ｃd が最も低下しているので、このレイノルズ数Ｒe で風圧低減効果がもっとも大きいといえる。ここでのレイノルズ数Ｒe を数１式から、各種サイズの電線外径においてどの風速に相当するか算出すると、外径９mmで風速49ｍ／ｓ、外径16mmで風速28ｍ／ｓ、外径20mmで風速22ｍ／ｓ、外径40mmで風速11ｍ／ｓに相当する。
【００１３】
また抗力係数Ｃd が増加し始めるのはレイノルズ数Ｒe ＝50000 であるので、この値で同様な換算を行うと、外径９mmで風速82ｍ／ｓ、外径16mmで風速46ｍ／ｓ、外径20mmで風速36ｍ／ｓ、外径40mmで風速19ｍ／ｓとなる。
【００１４】
したがって各々の電線において、風圧低減効果が得られる風速域は、外径９mmで風速49〜82ｍ／ｓ、外径16mmで風速28〜46ｍ／ｓ、外径20mmで風速22〜36ｍ／ｓ、外径40mmで風速11〜19ｍ／ｓとなる。このように同じ形状の電線でも、外径が異なると風圧低減効果が得られる風速域が違ってくるため、適用する電線サイズにおいて、風速40ｍ／ｓで効果が得られる形状を選定する必要がある。
【００１５】
そこで、ｒ、Ｒ、θ、ｈ／ｒ、レイノルズ数Ｒe が異なる種々の形状の電線について、実験を繰り返した結果、θが大きくなると、図２の曲線全体が高レイノルズ数側へシフトする傾向があり、ｈ／ｒが小さくなりレイノルズ数Ｒe が大きくなると、最低抗力係数の値が大きくなりながら高レイノルズ数側へシフトする（曲線全体が凹みが小さくなりつつ右上に移動する）傾向のあることが判明した。
【００１６】
このような傾向から、架空配電用の絶縁電線に相当するｒ＝4.5 mm〜20mmの範囲において、実用風速域（40ｍ／ｓ）で風圧低減効果が得られる形状をもとめた結果、θが10°〜22.5°好ましくは10°〜18°、ｈ／ｒが0.05〜0.2 好ましくは0.05〜0.10の範囲であることを見いだし、本発明を完成するに至ったものである。
【００１７】
さらに、風圧荷重低減効果とあわせて難着雪効果が得られる形状について、着雪実験を繰り返した結果、前記の条件にさらに、山部と谷部を電線長手方向に直線状に設け、山部の外接円の半径をＲとしたとき、山部の高さｈを、ｈ≧0.5 ×Ｒ×sin(θ／２) なる範囲にするという条件を加えることにより、難着雪効果が得られることを見いだしたものである。
【００１８】
従来の難着雪絶縁電線は、電線表面にヒレを設けることにより、電線表面に付着した雪の回転成長を防止するものであるが、本発明の絶縁電線は風圧荷重低減効果を得るために表面に山部と谷部を設けており、この山部と谷部が雪の回転成長を防止して、雪を落下させる効果を有しているものである。実験の結果、難着雪効果は、山部の高さｈと山部の開き角度θとの相関関係により得られることが判明し、山部の高さｈを、ｈ≧0.5 ×Ｒ×sin(θ／２) なる範囲に設定することにより難着雪効果が得られることを見いだしたものである。
【００１９】
【実施例】
図１のような絶縁電線で、絶縁被覆２のｒ、Ｒ、θ、ｈ／ｒ、0.5 ×Ｒ×sin(θ／２) の値を変えて、次のような絶縁電線を製造した。なお山部と谷部は電線長手方向に直線状に形成した。
〔実施例１〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝5.1mm 、θ＝18°、ｈ／ｒ＝0.14、ｈ＝0.63mm、0.5 ×Ｒ×sin(θ／２) ＝0.40mmの絶縁電線を得た。
〔実施例２〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝4.9mm 、θ＝18°、ｈ／ｒ＝0.09、ｈ＝0.41mm、0.5 ×Ｒ×sin(θ／２) ＝0.38mmの絶縁電線を得た。
〔実施例３〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝4.9mm 、θ＝12°、ｈ／ｒ＝0.08、ｈ＝0.36mm、0.5 ×Ｒ×sin(θ／２) ＝0.25mmの絶縁電線を得た。
〔実施例４〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.2mm 、θ＝10°、ｈ／ｒ＝0.05、ｈ＝0.39mm、0.5 ×Ｒ×sin(θ／２) ＝0.36mmの絶縁電線を得た。
〔実施例５〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.3mm 、θ＝12°、ｈ／ｒ＝0.06、ｈ＝0.47mm、0.5 ×Ｒ×sin(θ／２) ＝0.43mmの絶縁電線を得た。
〔実施例６〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.8mm 、θ＝18°、ｈ／ｒ＝0.13、ｈ＝1.01mm、0.5 ×Ｒ×sin(θ／２) ＝0.69mmの絶縁電線を得た。
〔実施例７〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.5mm 、θ＝18°、ｈ／ｒ＝0.09、ｈ＝0.70mm、0.5 ×Ｒ×sin(θ／２) ＝0.67mmの絶縁電線を得た。
〔実施例８〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.7mm 、θ＝22.5°、ｈ／ｒ＝0.11、ｈ＝0.86mm、0.5 ×Ｒ×sin(θ／２) ＝0.84mmの絶縁電線を得た。
〔実施例９〕
130mm²の銅より線にポリエチレンを押出被覆し、ｒ＝9.45mm、Ｒ＝10.8mm、θ＝18°、ｈ／ｒ＝0.14、ｈ＝1.32mm、0.5 ×Ｒ×sin(θ／２) ＝0.84mmの絶縁電線を得た。
〔実施例１０〕
500mm²の銅より線にポリエチレンを押出被覆し、ｒ＝18.0mm、Ｒ＝21.2mm、θ＝22.5°、ｈ／ｒ＝0.18、ｈ＝3.24mm、0.5 ×Ｒ×sin(θ／２) ＝2.07mmの絶縁電線を得た。
〔実施例１１〕
500mm²の銅より線にポリエチレンを押出被覆し、ｒ＝18.0mm、Ｒ＝20.0mm、θ＝22.5°、ｈ／ｒ＝0.11、ｈ＝1.98mm、0.5 ×Ｒ×sin(θ／２) ＝1.95mmの絶縁電線を得た。
〔実施例１２〕
500mm²の銅より線にポリエチレンを押出被覆し、ｒ＝18.0mm、Ｒ＝19.3mm、θ＝15°、ｈ／ｒ＝0.07、ｈ＝1.26mm、0.5 ×Ｒ×sin(θ／２) ＝1.26mmの絶縁電線を得た。
【００２０】
〔比較例１〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝5.1mm 、θ＝30°、ｈ／ｒ＝0.13、ｈ＝0.59mm、0.5 ×Ｒ×sin(θ／２) ＝0.66mmの絶縁電線を得た。
〔比較例２〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.8mm 、θ＝９°、ｈ／ｒ＝0.13、ｈ＝1.01mm、0.5 ×Ｒ×sin(θ／２) ＝0.35mmの絶縁電線を得た。
〔比較例３〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mmの、表面に凹凸のない通常の絶縁電線を得た。
〔比較例４〕
130mm²の銅より線にポリエチレンを押出被覆し、ｒ＝9.45mmの、表面に凹凸のない通常の絶縁電線を得た。
〔比較例５〕
500mm²のアルミより線にポリエチレンを押出被覆し、ｒ＝18.0mmの、表面に凹凸のない通常の絶縁電線を得た。
〔比較例６〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝4.9mm 、θ＝18°、ｈ／ｒ＝0.08、ｈ＝0.36mm、0.5 ×Ｒ×sin(θ／２) ＝0.38mmの絶縁電線を得た。
〔比較例７〕
外径５mmの銅単線にポリエチレンを押出被覆し、ｒ＝4.5 mm、Ｒ＝4.7mm 、θ＝12°、ｈ／ｒ＝0.05、ｈ＝0.23mm、0.5 ×Ｒ×sin(θ／２) ＝0.25mmの絶縁電線を得た。
〔比較例８〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.2mm 、θ＝12°、ｈ／ｒ＝0.05、ｈ＝0.39mm、0.5 ×Ｒ×sin(θ／２) ＝0.43mmの絶縁電線を得た。
〔比較例９〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.4mm 、θ＝18°、ｈ／ｒ＝0.08、ｈ＝0.62mm、0.5 ×Ｒ×sin(θ／２) ＝0.66mmの絶縁電線を得た。
〔比較例１０〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.3mm 、θ＝22.5°、ｈ／ｒ＝0.06、ｈ＝0.47mm、0.5 ×Ｒ×sin(θ／２) ＝0.81mmの絶縁電線を得た。
〔比較例１１〕
80mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.8 mm、Ｒ＝8.58mm、θ＝22.5°、ｈ／ｒ＝0.1 、ｈ＝0.78mm、0.5 ×Ｒ×sin(θ／２) ＝0.84mmの絶縁電線を得た。
〔比較例１２〕
500mm²の銅より線にポリエチレンを押出被覆し、ｒ＝18.0mm、Ｒ＝19.8mm、θ＝22.5°、ｈ／ｒ＝0.1 、ｈ＝1.8 mm、0.5 ×Ｒ×sin(θ／２) ＝1.93mmの絶縁電線を得た。
〔比較例１３〕
500mm²の銅より線にポリエチレンを押出被覆し、ｒ＝18.0mm、Ｒ＝19.1mm、θ＝15°、ｈ／ｒ＝0.06、ｈ＝1.08mm、0.5 ×Ｒ×sin(θ／２) ＝1.25mmの絶縁電線を得た。
〔比較例１４〕
60mm²の銅より線にポリエチレンを押出被覆し、ｒ＝7.5 mmの、表面に難着雪ヒレ以外の凹凸のない通常の難着雪絶縁電線を得た。
【００２１】
これらの絶縁電線について風洞実験を行い、レイノルズ数Ｒe と抗力係数Ｃd の関係を調べた。その結果を表１に示す。
【００２２】
【表１】

【００２３】
この結果によれば、実施例の電線は、いずれも風速40ｍ／ｓにおいて、通常の電線（比較例３、４、５）よりも大幅に抗力係数Ｃd が低下しているので、風圧低減効果があることが分かる。また、さらに好ましくは、θを10°〜18°、かつｈ／ｒを0.05〜0.10とすると、抗力係数Ｃd がさらに低下することが分かる。
よって、このような構成にすることにより、外径９〜40mm程度の電線においても風圧低減効果を著しく向上させることができる。
【００２４】
また、同じ絶縁電線について、図４に示すような難着雪特性評価装置を用いて、難着雪特性を評価した。この装置は、雪５を加振機６で振動させながら、ふるい７を通して落下させ、その雪に噴霧器８により水分を含ませて、ファン９からの送風により湿った雪を電線10に吹き付け、電線表面に付着させるものである。評価は、降雪10分間で電線表面に付着した雪が落下する回数をカウントし、これを５回繰り返して、平均値をとり、平均の落下回数が多いものほど難着雪効果が高いと判定する。この難着雪特性評価試験の結果を表１に併せて記載した。
【００２５】
実施例の、山部の高さｈをｈ≧0.5 ×Ｒ×sin(θ／２) とした電線は、いずれも２回以上雪が落下し、これは従来の難着雪絶縁電線（比較例１４、ヒレ付き）の難着雪効果より優れていることが分かる。
また表面にヒレも凹凸もない通常の絶縁電線（比較例３、４、５）は雪が落下せず、難着雪効果がないことが分かる。また表面に凹凸はあるが、ｈ＜0.5 ×Ｒ×sin(θ／２) である絶縁電線（比較例６〜１３）はいずれも0.2 〜0.4 回の落下であり、これは従来の難着雪絶縁電線（比較例１４、ヒレ付き）の難着雪効果より劣るものであることが分かる。
【００２６】
【発明の効果】
以上説明したように本発明によれば、比較的外径の小さい絶縁電線において、実用的な風速域（40ｍ／ｓ）で風圧荷重の小さい低風圧絶縁電線を得ることができる。また従来の難着雪絶縁電線と同等以上の難着雪性能を有する低風圧絶縁電線を得ることができる。
【図面の簡単な説明】
【図１】本発明による低風圧絶縁電線の一実施形態を示す断面図。
【図２】図１の形態の絶縁電線の、レイノルズ数Ｒe と抗力係数Ｃd の関係を示すグラフ。
【図３】（イ）、（ロ）は絶縁電線の周囲の風の流れの状態を示す説明図。
【図４】難着雪特性評価装置の説明図。
【符号の説明】
１：導体
２：絶縁被覆
３：山部
４：谷部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a low wind pressure insulated electric wire installed in an aerial manner and a low wind pressure insulated electric wire having a difficult snow landing performance.
[0002]
[Prior art]
In general, an insulated electric wire in which a copper or aluminum conductor is coated with an insulating coating (including a sheath) such as polyvinyl chloride, polyethylene, or cross-linked polyethylene is used as an overhead distribution line. Conventional insulated wires have a circular cross section and a smooth outer peripheral surface, and no particular measures have been taken to reduce wind pressure.
[0003]
On the other hand, as one means for reducing the wind pressure load of an electric wire, Japanese Patent Laid-Open No. 3-74009 discloses a large number of ridges and a large number of ridges sandwiched between the ridges at intervals in the circumferential direction on the outer peripheral surface of the electric wire. It is disclosed that it is good to provide the trough part. In general, when a normal insulated wire having no irregularities on the surface is placed in the wind at a right angle to the wind direction, an air flow separation point P occurs on the windward side of the insulated wire as shown in FIG. Since a large wake area is formed on the leeward side of the electric wire, the wind pressure increases. On the other hand, when a large number of irregularities are provided on the outer peripheral surface of the insulated wire, a phenomenon in which the air flow separated at the point P due to the presence of the irregularities is reattached at the point Q as shown in FIG. Is generated, and the wake area is reduced, so that the wind pressure is considered to be reduced. This has been confirmed by experiments.
[0004]
[Problems to be solved by the invention]
However, conventional wind pressure reduction means can be applied to practical wind speed ranges (40 m / s: “technical standards for electrical equipment”) when applied to insulated wires with an outer diameter of about 9 to 40 mm, such as overhead distribution lines. There was a problem that a sufficient wind pressure reduction effect could not be obtained under the design condition class A).
Moreover, even if the electric wire has a wind pressure load reduction effect, it may not be possible to obtain the wind pressure load reduction effect because snow adheres to the wire surface during snowfall.
[0005]
The first object of the present invention is to solve the above-described problems and provide a low wind pressure insulated electric wire with a small wind pressure load in a practical wind speed range.
The second object of the present invention is to provide a low wind pressure insulated electric wire having further difficult snow accretion performance.
[0006]
[Means for Solving the Problems]
In order to achieve the first object, the present invention provides an insulated wire in which an insulation coating is provided on the outer periphery of a conductor, and a plurality of crests at predetermined intervals in the circumferential direction on the outer periphery of the insulation coating. And a plurality of valleys sandwiched between the peaks, the peaks are outwardly convex curved surfaces, the valleys are outwardly concave curved surfaces, and the peaks and valleys are smoothly connected. And the radius of the inscribed circle of the valley is r, the height of the peak is h (the same as the depth of the valley), and the opening angle of the adjacent peaks is θ (the same as the opening angle between the adjacent valleys) ), R is 4.5 mm to 20 mm, θ is 10 ° to 22.5 °, and h / r is 0.05 to 0.2.
[0007]
In order to achieve the second object, in the low wind pressure insulated electric wire as described above, the present invention provides a crest and a trough in a straight line in the longitudinal direction of the electric wire, and the radius of the circumscribed circle of the crest is R. The relationship is h ≧ 0.5 × R × sin (θ / 2).
In this way, it is possible to obtain a snowfalling effect that makes it difficult for snow to adhere to the surface of the electric wire.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of an insulated wire according to the present invention. In the figure, 1 is a conductor, 2 is an insulating coating (including a sheath), 3 is a crest formed on the outer peripheral surface of the insulating coating, and 4 is a trough between the crests 3. Each crest 3 is a rounded convex surface, each trough 4 is a rounded concave surface, and the curved surface of the crest 3 and the curved surface of the trough 4 are smoothly connected (for example, crest 3 And the curved surface of the valley 4 are connected by a common tangent) . Moreover, the peak part 3 and the trough part 4 are formed in the linear form or the spiral form in the electric wire longitudinal direction.
[0009]
And this insulated wire is characterized by the fact that r is 4.5 mm when r is the radius of the inscribed circle of the valley 3, h is the height of the peak 3, and θ is the opening angle between the adjacent peaks 3. 20 mm, θ is set to 10 ° to 22.5 °, and h / r is set to a range of 0.05 to 0.2. The range of r corresponds to the radius of insulated wires of 600 V to 33 kV class generally used for overhead power distribution.
[0010]
The fact that the wind pressure reduction effect can be obtained in such a range has been found from the following examination results.
The aerodynamic characteristics of electric wires and the like are generally evaluated by the relationship between the drag coefficient Cd and the Reynolds number Re. The Reynolds number Re is expressed by the following equation.
[0011]
[Expression 1]

[0012]
FIG. 2 shows the results of measuring the relationship between the drag coefficient Cd and the Reynolds number Re for the insulated wire having the shape of FIG. According to this data, for example, since the drag coefficient Cd is the lowest at Reynolds number Re = 30000, it can be said that the effect of reducing the wind pressure is the largest at this Reynolds number Re. The Reynolds number Re here is calculated from the equation (1) by calculating which wind speed corresponds to the outer diameter of various sizes of wires. When the outer diameter is 9 mm, the wind speed is 49 m / s, when the outer diameter is 16 mm, the wind speed is 28 m / s, and the outer diameter is 20 mm. It corresponds to a wind speed of 11 m / s with a wind speed of 22 m / s and an outer diameter of 40 mm.
[0013]
The drag coefficient Cd begins to increase when the Reynolds number Re is 50000. If the same conversion is performed with this value, the wind speed is 82 m / s at an outer diameter of 9 mm, the wind speed is 46 m / s at an outer diameter of 16 mm, and the outer diameter is 20 mm. The wind speed is 36 m / s, the outer diameter is 40 mm, and the wind speed is 19 m / s.
[0014]
Therefore, in each electric wire, the wind speed range where the wind pressure reduction effect can be obtained is the wind speed 49-82m / s at the outer diameter 9mm, the wind speed 28-46m / s at the outer diameter 16mm, the wind speed 22-36m / s at the outer diameter 20mm, the outer The wind speed is 11 to 19 m / s at a diameter of 40 mm. Thus, even with the same shape of the electric wire, the wind speed range where the effect of reducing the wind pressure is different if the outer diameter is different. Therefore, it is necessary to select a shape that can obtain the effect at a wind speed of 40 m / s in the applied wire size. .
[0015]
Therefore, as a result of repeating the experiment on various shapes of electric wires having different r, R, θ, h / r, and Reynolds number Re, when θ increases, the entire curve in FIG. 2 tends to shift toward the high Reynolds number. Yes, when h / r decreases and the Reynolds number Re increases, the value of the minimum drag coefficient increases and the value tends to shift to the higher Reynolds number (the entire curve moves to the upper right while the dent becomes smaller). found.
[0016]
From this tendency, as a result of seeking a shape that can reduce the wind pressure in the practical wind speed range (40 m / s) in the range of r = 4.5 mm to 20 mm, which corresponds to an insulated wire for overhead power distribution, θ is 10 ° It has been found that ˜22.5 °, preferably 10 ° to 18 ° and h / r is in the range of 0.05 to 0.2, preferably 0.05 to 0.10, and the present invention has been completed.
[0017]
Further, as a result of repeating the snow accumulating experiment on the shape that can obtain the difficult snow accretion effect in combination with the wind pressure load reducing effect, the mountain portion and the valley portion are provided in a straight line in the longitudinal direction of the electric wire in addition to the above conditions, and the mountain portion When the radius of the circumscribed circle of R is R, by adding the condition that the height h of the ridge is in the range of h ≧ 0.5 × R × sin (θ / 2), it is possible to obtain a difficult snow accretion effect It was something that was found.
[0018]
Conventional hard-to-snow insulated electric wires are designed to prevent the rotational growth of snow attached to the surface of the wires by providing fins on the surface of the wires. The ridges and valleys are provided, and the ridges and valleys have the effect of preventing the snow from falling and preventing the snow from falling. As a result of experiments, it has been found that the effect of difficult snow accretion is obtained by the correlation between the height h of the mountain portion and the opening angle θ of the mountain portion, and the height h of the mountain portion is expressed as h ≧ 0.5 × R × sin. It has been found that a snowfall effect can be obtained by setting in the range of (θ / 2).
[0019]
【Example】
With the insulated wires as shown in FIG. 1, the following insulated wires were manufactured by changing the values of r, R, θ, h / r, and 0.5 × R × sin (θ / 2) of the insulation coating 2. In addition, the peak part and the trough part were formed linearly in the electric wire longitudinal direction.
[Example 1]
Polyethylene is extrusion coated on a copper single wire with an outer diameter of 5 mm, r = 4.5 mm, R = 5.1 mm, θ = 18 °, h / r = 0.14, h = 0.63 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.40 mm was obtained.
[Example 2]
Polyethylene is extrusion coated on a copper single wire with an outer diameter of 5 mm, r = 4.5 mm, R = 4.9 mm, θ = 18 °, h / r = 0.09, h = 0.41 mm, 0.5 × R × sin (θ / 2) = A 0.38 mm insulated wire was obtained.
Example 3
Polyethylene is extrusion coated on a copper single wire with an outer diameter of 5 mm, r = 4.5 mm, R = 4.9 mm, θ = 12 °, h / r = 0.08, h = 0.36 mm, 0.5 × R × sin (θ / 2) = A 0.25 mm insulated wire was obtained.
Example 4
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.2 mm, θ = 10 °, h / r = 0.05, h = 0.39 mm, 0.5 × R × sin (θ / 2) = A 0.36 mm insulated wire was obtained.
Example 5
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.3 mm, θ = 12 °, h / r = 0.06, h = 0.47 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.43 mm was obtained.
Example 6
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.8 mm, θ = 18 °, h / r = 0.13, h = 1.01 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.69 mm was obtained.
Example 7
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.5 mm, θ = 18 °, h / r = 0.09, h = 0.70 mm, 0.5 × R × sin (θ / 2) = A 0.67 mm insulated wire was obtained.
Example 8
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.7 mm, θ = 22.5 °, h / r = 0.11, h = 0.86 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.84 mm was obtained.
Example 9
130 mm ² copper strand is extrusion coated with polyethylene, r = 9.45 mm, R = 10.8 mm, θ = 18 °, h / r = 0.14, h = 1.32 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.84 mm was obtained.
Example 10
500 mm ² copper strand is extrusion coated with polyethylene, r = 18.0 mm, R = 21.2 mm, θ = 22.5 °, h / r = 0.18, h = 3.24 mm, 0.5 × R × sin (θ / 2) = A 2.07 mm insulated wire was obtained.
Example 11
500 mm ² copper strand is extrusion coated with polyethylene, r = 18.0 mm, R = 20.0 mm, θ = 22.5 °, h / r = 0.11, h = 1.98 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 1.95 mm was obtained.
Example 12
500 mm ² copper strand is extrusion coated with polyethylene, r = 18.0 mm, R = 19.3 mm, θ = 15 °, h / r = 0.07, h = 1.26 mm, 0.5 × R × sin (θ / 2) = A 1.26 mm insulated wire was obtained.
[0020]
[Comparative Example 1]
Polyethylene is extrusion coated on a copper single wire with an outer diameter of 5 mm, r = 4.5 mm, R = 5.1 mm, θ = 30 °, h / r = 0.13, h = 0.59 mm, 0.5 × R × sin (θ / 2) = A 0.66 mm insulated wire was obtained.
[Comparative Example 2]
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.8 mm, θ = 9 °, h / r = 0.13, h = 1.01 mm, 0.5 × R × sin (θ / 2) = A 0.35 mm insulated wire was obtained.
[Comparative Example 3]
An 80 mm ² copper strand was extrusion coated with polyethylene to obtain a normal insulated wire with r = 7.8 mm and no irregularities on the surface.
[Comparative Example 4]
A 130 mm ² copper stranded wire was extrusion coated with polyethylene to obtain a normal insulated wire with r = 9.45 mm and no irregularities on the surface.
[Comparative Example 5]
A 500 mm ² aluminum strand wire was extrusion coated with polyethylene to obtain a normal insulated wire with r = 18.0 mm and no irregularities on the surface.
[Comparative Example 6]
Polyethylene is extrusion coated on a copper single wire having an outer diameter of 5 mm, r = 4.5 mm, R = 4.9 mm, θ = 18 °, h / r = 0.08, h = 0.36 mm, 0.5 × R × sin (θ / 2) = A 0.38 mm insulated wire was obtained.
[Comparative Example 7]
Polyethylene is extrusion coated on a copper single wire having an outer diameter of 5 mm, r = 4.5 mm, R = 4.7 mm, θ = 12 °, h / r = 0.05, h = 0.23 mm, 0.5 × R × sin (θ / 2) = A 0.25 mm insulated wire was obtained.
[Comparative Example 8]
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.2 mm, θ = 12 °, h / r = 0.05, h = 0.39 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.43 mm was obtained.
[Comparative Example 9]
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.4 mm, θ = 18 °, h / r = 0.08, h = 0.62 mm, 0.5 × R × sin (θ / 2) = A 0.66 mm insulated wire was obtained.
[Comparative Example 10]
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.3 mm, θ = 22.5 °, h / r = 0.06, h = 0.47 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.81 mm was obtained.
[Comparative Example 11]
80 mm ² copper strand is extrusion coated with polyethylene, r = 7.8 mm, R = 8.58 mm, θ = 22.5 °, h / r = 0.1, h = 0.78 mm, 0.5 × R × sin (θ / 2) = An insulated wire of 0.84 mm was obtained.
[Comparative Example 12]
500 mm ² copper strand is extrusion coated with polyethylene, r = 18.0 mm, R = 19.8 mm, θ = 22.5 °, h / r = 0.1, h = 1.8 mm, 0.5 × R × sin (θ / 2) = A 1.93 mm insulated wire was obtained.
[Comparative Example 13]
A 500 mm ² copper strand is extrusion coated with polyethylene, r = 18.0 mm, R = 19.1 mm, θ = 15 °, h / r = 0.06, h = 1.08 mm, 0.5 × R × sin (θ / 2) = A 1.25 mm insulated wire was obtained.
[Comparative Example 14]
A 60 mm ² copper strand was extrusion-coated with polyethylene to obtain a normal snow-insulated insulated wire with r = 7.5 mm and no irregularities other than difficult snow fins on the surface.
[0021]
Wind tunnel experiments were conducted on these insulated wires, and the relationship between Reynolds number Re and drag coefficient Cd was examined. The results are shown in Table 1.
[0022]
[Table 1]

[0023]
According to this result, since the drag coefficient Cd of each of the electric wires in the examples is significantly lower than that of a normal electric wire (Comparative Examples 3, 4, and 5) at a wind speed of 40 m / s, the effect of reducing the wind pressure is obtained. I understand that there is. More preferably, when θ is 10 ° to 18 ° and h / r is 0.05 to 0.10, the drag coefficient Cd is further reduced.
Therefore, with such a configuration, the effect of reducing the wind pressure can be remarkably improved even in an electric wire having an outer diameter of about 9 to 40 mm.
[0024]
Further, for the same insulated wire, the hard snow arrival characteristics were evaluated using a hard snow arrival characteristic evaluation apparatus as shown in FIG. This device drops snow 5 through a sieve 7 while vibrating it with a vibrator 6, adds moisture to the snow by a sprayer 8, and blows wet snow by blowing air from a fan 9 onto an electric wire 10. It is attached to the surface. In the evaluation, the number of times the snow attached to the surface of the electric wire falls within 10 minutes of snowfall is counted, and this is repeated five times to obtain an average value. The results of the difficult snow accretion characteristic evaluation test are also shown in Table 1.
[0025]
In each of the electric wires in which the height h of the mountain portion is h ≧ 0.5 × R × sin (θ / 2), the snow falls twice or more, which is a conventional snow-resistant insulated wire (Comparative Example 14). It can be seen that it is superior to the hard snowfall effect of (with fins).
Moreover, it turns out that a normal insulated wire (Comparative Examples 3, 4, and 5) which has neither a fin nor an unevenness | corrugation on the surface does not fall snow, and there is no effect of difficult snowfall. In addition, although the surface is uneven, the insulated wires (Comparative Examples 6 to 13) with h <0.5 × R × sin (θ / 2) all fall 0.2 to 0.4 times, which is the conventional difficulty in snowing. It turns out that it is inferior to the hard snowfall effect of an insulated wire (Comparative example 14, with a fin).
[0026]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain a low wind pressure insulated wire with a small wind pressure load in a practical wind speed range (40 m / s) in an insulated wire having a relatively small outer diameter. Moreover, the low wind pressure insulated electric wire which has the snow-resistant performance equivalent to or more than the conventional snow-insulated insulated wire can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of a low wind pressure insulated electric wire according to the present invention.
FIG. 2 is a graph showing the relationship between the Reynolds number Re and the drag coefficient Cd of the insulated wire in the form of FIG.
FIGS. 3A and 3B are explanatory diagrams showing the state of wind flow around the insulated wires. FIGS.
FIG. 4 is an explanatory diagram of a difficult snow landing characteristic evaluation apparatus.
[Explanation of symbols]
1: Conductor 2: Insulation coating 3: Mountain part 4: Valley part

Claims

In an insulated wire provided with an insulation coating on the outer periphery of the conductor, a large number of crests and a plurality of troughs sandwiched between the crests at predetermined intervals in the circumferential direction on the outer peripheral surface of the insulation coating The ridge is an outwardly convex curved surface, the valley is an outwardly concave curved surface, and the curved surface of the ridge and the curved surface of the valley are smoothly connected, and the radius of the inscribed circle of the valley is r, When the height of the peak is h and the opening angle of the adjacent peak is θ, r is in the range of 4.5 mm to 20 mm, θ is in the range of 10 ° to 22.5 °, and h / r is in the range of 0.05 to 0.2. Low wind pressure insulated wire.

The crest and trough are provided in a straight line in the longitudinal direction of the electric wire, and the radius of the circumscribed circle of the crest is R, h ≧ 0.5 × R × sin (θ / 2). Item 2. The low wind pressure insulated electric wire according to Item 1.