JP3469759B2 - Method of cross-linking reinforcing insulation layer at mold connection of cross-linked polyethylene cable - Google Patents
Method of cross-linking reinforcing insulation layer at mold connection of cross-linked polyethylene cableInfo
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- JP3469759B2 JP3469759B2 JP30551797A JP30551797A JP3469759B2 JP 3469759 B2 JP3469759 B2 JP 3469759B2 JP 30551797 A JP30551797 A JP 30551797A JP 30551797 A JP30551797 A JP 30551797A JP 3469759 B2 JP3469759 B2 JP 3469759B2
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- insulating layer
- temperature
- cross
- reinforcing insulating
- heater
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Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は架橋ポリエチレンケ
ーブルにおけるモールド接続部補強絶縁層の架橋方法に
関し、特に本発明は架橋工程において加熱温度コントロ
ールを行うことにより、接続部の熱融着をより良くし絶
縁性能の安定化、信頼性の向上を図ることができるモー
ルド接続部補強絶縁層の架橋方法に関するものである。
【０００２】
【従来の技術】従来から、電力架橋ポリエチレンケーブ
ルの接続部を形成するにあたって種々の工法が知られて
いる。特に、超高圧ケーブルにおいては電気的性能をよ
り高めるために、ＥＭＪ（押し出しモールド・ジョイン
ト）、ＢＭＪ（ブロックモールド・ジョイント）といっ
たモールド方式の接続部が用いられている。一般に、Ｅ
ＭＪでは、ケーブル端末を段剥ぎし導体を接続した後、
内部半導電層を取り付ける前処理工程を行い、押出し機
を用いて電力ケーブル導体接続部上に設けた押出し金型
内に架橋剤入りポリエチレン樹脂を補強絶縁体として充
填し、金型を取り外し補強絶縁体を切削・整形した後、
収縮性チューブ等で保護し、更に加熱用ヒータを巻き付
けた後、架橋金型内に収め、窒素等のガスを用いて外部
より加圧を行い架橋を行う。
【０００３】ＢＭＪでは、予め工場等で成形された未架
橋の筒状の補強絶縁体ブロックに、その両端から端末を
段剥ぎし、導体部分に接続子が圧着された接続しようと
する２本の電力架橋ポリエチレンケーブルを挿入し、こ
の補強絶縁ブロックを高圧下に保った架橋金型内にて窒
素等のガスを用いて加圧し、補強絶縁ブロックをヒータ
で加熱し架橋を行う。
【０００４】本発明者らは、架橋ポリエチレン・ケーブ
ルのモールド接続における上記補強絶縁体の加熱に関し
て先に特願平４−１９１０６３号（特開平６−３８３３
３号公報）により次の技術を提案した。未架橋のポリエ
チレンからなる補強絶縁層を接続部上に形成した後に、
これを架橋処理するにあたり、少なくとも接続部長手方
向に３分割された面状ヒータで接続部全体を被覆ないし
囲繞して２つ割りの密閉型架橋管内に収納し、面状ヒー
タによる高温加熱により、各層を架橋、融着させてい
る。
【０００５】
【発明が解決しようとする課題】上記した従来技術で施
工された接続部でも、ケーブル絶縁体と補強絶縁層の界
面が存在している。図６はケーブル接続部の構造を示す
図であり、同図はケーブル接続部の上半分の断面構造を
示している。同図において、１はケーブル絶縁体、２は
補強絶縁層、３はモールド外部半導電層、４はモールド
内部半導電層である。架橋工程において、図６に示すケ
ーブル絶縁体１と補強絶縁層２との接着が進行するが、
ケーブル絶縁体１は架橋剤が完全に分解した架橋ポリエ
チレンであることから、ケーブル絶縁体１や補強絶縁層
２と比べ界面にはミクロボイドが生成し易い。
【０００６】特に、２７５ｋＶを越える超高圧電力ケー
ブル接続部においは補強絶縁層２の体積が大きく、界面
全体において、融着、架橋が進行する時間にバラツキが
存在する。例えば、架橋工程のある時点において、接続
部端部に近い界面では補強絶縁層とケーブル絶縁体の融
着が完了し該界面付近の補強絶縁層の架橋が進行する一
方、接続部中央付近の界面では融着すら進行していない
といった状況が存在している。このように、界面全体に
わたり完全な融着が進行していない状況において、ある
界面付近の補強絶縁層の架橋が進行した場合、界面にミ
クロボイドが発生したり気泡が残ってしまう。
【０００７】本発明は上記した従来技術の問題点に鑑み
なされたものであって、その目的とするところは、２７
５ｋＶを越える超高圧電力ケーブル接続部に適用するに
好適な、界面にミクロボイドが生成せず、また気泡が残
存することがない、電気的に優れた性能を有する電力Ｃ
Ｖケーブルモールド接続部補強絶縁層の架橋方法を提供
することである。
【０００８】
【課題を解決するための手段】上記課題を解決するた
め、本発明においては、架橋を行う接続部の長手方向に
沿って複数に分割されたヒータの制御において、接続部
中央を分担するヒータの架橋のための目標温度に至る時
刻を、接続部の右端と左端を分担するヒータの架橋のた
めの目標温度に至る時刻より３時間以上先んじさせ、そ
の間、前記右端と左端を分担するヒータをケーブル絶縁
体と補強絶縁層の界面が上記補強絶縁層の融点より高い
温度になるような温度に維持させる。これにより、ケー
ブル絶縁体と補強絶縁層界面全体の融着を、該界面のま
だ補強絶縁層の架橋が進行していない状況において完了
させかつ架橋の終了を補強絶縁層中央から端部へ進行さ
せることができる。ところで、上記接続部の右端と左端
を分担するヒータの昇温の途中で、右端と左端を分担す
るヒータをケーブル絶縁体と補強絶縁層の界面が上記補
強絶縁層の融点より高い温度になるように維持させる温
度としては１００℃〜１３０℃が望ましい。
【０００９】
【発明の実施の形態】本発明においては、前記したよう
に架橋を行う接続部の長手方向に沿って複数に分割され
たヒータの接続部中央を分担するヒータの架橋のための
目標温度に至る時刻を、接続部の右端と左端を分担する
ヒータの架橋のための目標温度に至る時刻より３時間以
上先んじさせ、その間、前記右端と左端を分担するヒー
タをケーブル絶縁体と補強絶縁層の界面が上記補強絶縁
層の融点より高い温度になるような温度に維持させる。
このため、上記接続部の右端と左端を分担するヒータの
昇温の途中で、上記ヒータの温度を架橋のための目標値
よりも低く、上記補強絶縁層の融点より高い温度で又は
融点温度で一定時間保持させる。ここで、補強絶縁層と
ケーブル絶縁体をどこでも均一に融着させるためには、
肉厚の厚い補強絶縁層中央を分担するヒータを早く昇温
させ、中央部分が融着するのを待ってから、補強絶縁層
の薄い両端部を融着させねばならない。そして、接続部
の右端部、左端部を分担するヒータを架橋のための目標
温度より低い温度で保持する時間は、少なくとも２時間
以上必要であり、これより短時間では、中央部融着が終
了しないうちに、両端の架橋が進行してしまう。
【００１０】図３（ａ）は、本発明の方法と従来方法
（複数の分割したヒータを同時にオンとし、目標温度に
至る時刻を同じにした場合）における架橋昇温時の温度
履歴の一例を示す図であり、同図中の白丸、白三角は本
発明の方法、黒丸、黒三角は従来方法の温度履歴を示
し、白丸、黒丸はケーブル絶縁体の平坦中央部の界面
〔図３（ｂ）におけるＡ点〕、白三角、黒三角は、鉛筆
部肩部〔ケーブル絶縁体が先細に成っている部分の肩
部：図３（ｂ）におけるＢ点〕の界面の温度履歴を示し
ている。
【００１１】同図から、昇温初期においては平坦部中央
の温度が鉛筆肩部の温度より高いのであるが、本発明の
加熱方法を用いた場合、樹脂融点以下においてそれらの
温度は逆転している。一方、従来方法では、それらの温
度は融点以上において逆転している。つまり、平坦部中
央の温度が先に上昇し、後から鉛筆肩部の温度が追いか
けているので、補強絶縁層端から溶けていた。このた
め、補強絶縁層とケーブル絶縁体界面に存在する残留ガ
スは、そのまま界面に取り残され、界面にミクロボイド
が発生することになる。
【００１２】
【実施例】以下、本発明の接続部補強絶縁層の架橋方法
の実施例について説明する。まず、接続すべき２本のケ
ーブルを各々段剥ぎし、露呈した導体を接続した上に内
部半導電層を施工した後、未架橋ポリエチレン押出用の
金型を設置し、押出金型内の上記半導電層上に押出機を
用いて未架橋ポリエチレンを補強絶縁層として充填する
押し出しを行った。未架橋ポリエチレン押し出し後、押
出金型を取り外し補強絶縁層を所定の形状の切削整形
し、次いで窒素ガス等により外部より加圧しながら、接
続部の長手方向に沿って接続部両端部１／６ずつおよび
中央２／３に長さ方向を互いに分担したヒータで加熱し
た。
【００１３】図１は上記のように３分割されたヒータを
補強絶縁層の上に装着し、架橋管を取り付けた状態を示
す図であり、同図はケーブル接続部の上半分の断面構造
を示している。同図において、１はケーブル絶縁体、２
は補強絶縁層、３は外部半導電層、４は内部半導電層、
５は導体接続管、６は架橋管、７は保護層であり、架橋
管６の内部には窒素ガスが封入され加圧されている。ま
た、Ｈ１〜Ｈ３はヒータであり、ヒータＨ１〜Ｈ３はケ
ーブル接続部の中央、左端部、および、右端部の加熱用
に３分割されている。
【００１４】図２は上記ヒータと温度制御装置との接続
態様を示す図である。同図に示すように、補強絶縁層２
の中央部分、右端部、左端部を加熱するヒータＨ１〜Ｈ
３の温度を計測するセンサＳ１〜Ｓ３を取り付け、セン
サＳ１〜Ｓ３および上記ヒータＨ１〜Ｈ３からの引出し
線を架橋管５を貫通させて外部に引き出し、温度制御器
Ｃｎ１〜Ｃｎ３に接続した。温度制御器Ｃｎ１〜Ｃｎ３
は、センサＳ１〜Ｓ３の検出出力に基づき、各ヒータＨ
１〜Ｈ３の温度を所定の温度パターンで制御する。
【００１５】本実施例では、上記ヒータＨ１〜Ｈ３の
内、補強絶縁層２の中央部を加熱するヒータＨ２の架橋
のための目標温度に至る時刻を、補強絶縁層２の右端
部、左端部を加熱するヒータＨ１，Ｈ３の架橋のための
目標温度に至る時刻より３時間以上先んじさせた。ま
た、補強絶縁層２の右端部、左端部を加熱するヒータＨ
１，Ｈ３の昇温の途上で、補強絶縁層２の温度が補強絶
縁層２の融点以上で、架橋が進行しない温度以下の一定
温度になるように、ヒータＨ１，Ｈ３の温度を一定値に
保持した。上記補強絶縁層２の中央部を加熱するヒータ
Ｈ２の制御温度は例えば２２０°であり、補強絶縁層２
の右端部、左端部を加熱するヒータＨ１，Ｈ３の架橋の
ための制御温度は例えば１８０°である。
【００１６】本実施例における温度制御条件を図４
（ａ）〜（ｃ）に示し、また、比較例として、本発明の
条件から外れた条件で施工した場合の温度制御条件を図
５（ａ）〜（ｃ）に示す。なお、図４、図５の施工例で
は、温度制御条件以外の条件は同一とした。図４、図５
において、太線は補強絶縁層の中央部を加熱するヒータ
の温度を示し、点線は補強絶縁層の右端部、左端部を加
熱するヒータの温度を示しており、横軸は時間、縦軸は
温度である。
【００１７】図４、図５に示す温度制御条件で施工した
モールド接続部から、ケーブル絶縁体と補強絶縁層界面
を図１のＡの位置より切り出し、４００倍の光学顕微鏡
にて界面のボイドを、面積２５ｍｍ２の範囲にわたって
調査し、界面のボイドの有無を調べた。表１は図４、図
５の温度制御条件で施工したモールド接続部のボイドの
有無を示す表であり、表１から次のことが明らかとなっ
た。
【００１８】
【表１】【００１９】実施例１〜３については、前記したよう
に、補強絶縁層２の中央部を加熱するヒータＨ２の架橋
のための目標温度に至る時刻を、補強絶縁層２の右端
部、左端部を加熱するヒータＨ１，Ｈ３の架橋のための
目標温度に至る時刻より３時間以上先んじさせた。ま
た、補強絶縁層２の右端部、左端部を加熱するヒータＨ
１，Ｈ３の昇温の途上で、補強絶縁層２の温度が補強絶
縁層２の融点以上で、架橋が進行しない温度以下の一定
温度になるように、ヒータＨ１，Ｈ３の温度を一定値に
保持した。
【００２０】その結果、表１に示すように界面に全くボ
イドが発生しなかった。これは、補強絶縁層２の右端
部、左端部の架橋が進行する前に、ケーブル絶縁体と補
強絶縁層界面全体の融着が均一かつ十分に進行し、その
後架橋が進行したためと考えられる。これに対して、図
５の比較例１〜３では、ケーブル絶縁体と補強絶縁層界
面にボイドが発生した。
【００２１】比較例１については、補強絶縁層端部を加
熱するヒータＨ２が早く高くなってしまったため、架橋
のための目標温度に至る時刻が早くなり、補強絶縁層中
央部にボイドが発生したものと考えられる。比較例２に
ついては、補強絶縁層右端部、左端部を加熱するヒータ
Ｈ１，Ｈ３をその昇温の途上において一定に保持する
際、保持する温度が低すぎることから、補強絶縁層右端
部、左端部の界面の融着が十分進行しなかったためにボ
イドが発生したものと考えられる。
【００２２】比較例３については、補強絶縁層右端部、
左端部を加熱するヒータＨ１，Ｈ３をその昇温の途上に
おいて一定に保持する際、保持する温度が高すぎること
から、補強絶縁層中央部の界面の融着が進行する前に、
補強絶縁層右端部、左端部の融着が進行したため、ボイ
ドが発生したものと考えられる。なお、上記実施例で
は、ＥＭＪ方式のモールド接続部の場合について説明し
たが、ＢＭＪ方式を用いた場合も同様に実施することが
でき、同様の効果が期待される。
【００２３】
【発明の効果】以上説明したように本発明においては、
ケーブル絶縁体と補強絶縁層界面を均一に融着させてか
ら架橋を進行させることができるので、界面にボイドが
ほとんど発生せず、電気的特性の優れたモールド接続部
を施工することができ、その産業上の利用価値は極めて
大きい。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cross-linking a reinforcing layer of a mold connecting portion in a cross-linked polyethylene cable, and more particularly to a method of controlling a heating temperature in a cross-linking step. The present invention relates to a method for cross-linking a mold-connecting-portion reinforcing insulating layer, which can improve the thermal fusion of a connecting portion, stabilize insulating performance, and improve reliability. Conventionally, various methods have been known for forming a connection portion of a power crosslinked polyethylene cable. In particular, in the ultra-high voltage cable, in order to further improve the electrical performance, a connection part of a molding method such as EMJ (extrusion molding joint) and BMJ (block molding joint) is used. In general, E
In MJ, after stripping off the cable end and connecting the conductor,
Perform a pretreatment step of attaching the internal semiconductive layer, and use an extruder to fill the extrusion mold provided on the power cable conductor connection with polyethylene resin containing a cross-linking agent as a reinforcing insulator, remove the mold, and perform reinforcement insulation After cutting and shaping the body,
After being protected by a shrinkable tube or the like, and further wrapped with a heater for heating, it is placed in a cross-linking mold and cross-linked by externally applying pressure using a gas such as nitrogen. [0003] In BMJ, terminals are peeled off from both ends of an uncrosslinked tubular reinforcing insulator block formed in advance at a factory or the like, and a connector is crimped to a conductor portion to connect the two. A power cross-linked polyethylene cable is inserted, and the reinforcing insulating block is pressurized using a gas such as nitrogen in a cross-linking mold maintained at a high pressure, and the reinforcing insulating block is heated by a heater to perform cross-linking. The inventors of the present invention have previously disclosed in Japanese Patent Application No. Hei 4-19063 (Japanese Patent Application Laid-Open No. Hei 6-3833) the heating of the reinforcing insulator in the mold connection of a crosslinked polyethylene cable.
No. 3) proposed the following technology. After forming a reinforcing insulating layer made of uncrosslinked polyethylene on the connection part,
At the time of the crosslinking treatment, the entire connecting portion is covered or surrounded by at least a planar heater divided into three portions in the longitudinal direction of the connecting portion and housed in a two-piece closed bridge tube. Each layer is crosslinked and fused. [0005] Even in the connection portion constructed by the above-described conventional technique, there is an interface between the cable insulator and the reinforcing insulating layer. FIG. 6 is a diagram showing the structure of the cable connection portion, and FIG. 6 shows a cross-sectional structure of the upper half of the cable connection portion. In the figure, 1 is a cable insulator, 2 is a reinforcing insulating layer, 3 is a mold outer semiconductive layer, and 4 is a mold inner semiconductive layer. In the cross-linking step, the adhesion between the cable insulator 1 and the reinforcing insulating layer 2 shown in FIG.
Since the cable insulator 1 is a cross-linked polyethylene in which the cross-linking agent is completely decomposed, microvoids are easily generated at the interface as compared with the cable insulator 1 and the reinforcing insulating layer 2. In particular, in the connection portion of an ultra-high-voltage power cable exceeding 275 kV, the volume of the reinforcing insulating layer 2 is large, and there is variation in the time required for fusion and crosslinking to proceed at the entire interface. For example, at a certain point in the cross-linking step, fusion of the reinforcing insulating layer and the cable insulator is completed at the interface near the end of the connecting portion and bridging of the reinforcing insulating layer near the interface progresses, while the interface near the center of the connecting portion advances. There is a situation where even fusion has not progressed. As described above, in a situation where complete fusion has not progressed over the entire interface, if the bridging of the reinforcing insulating layer near a certain interface progresses, microvoids are generated at the interface or bubbles remain. The present invention has been made in view of the above-mentioned problems of the prior art.
An electric power C which is suitable for application to an ultra-high voltage power cable connection exceeding 5 kV and has excellent electrical performance without generating microvoids at the interface and leaving no bubbles.
An object of the present invention is to provide a method for cross-linking a V-cable mold connection reinforcing insulating layer. According to the present invention, in order to solve the above-mentioned problems, in the control of the heater divided into a plurality of portions along the longitudinal direction of the connecting portion to be bridged, the center of the connecting portion is shared. the time to reach the target temperature for the heater crosslinking, 3 hours allowed ahead more than the time to reach the target temperature for the crosslinking of the heater to share the right and left of the connection part, its
Insulation of the heater sharing the right and left ends
The interface between the body and the reinforcing insulating layer is higher than the melting point of the reinforcing insulating layer
Ru is maintained at a temperature such that the temperature. Thereby, the fusion of the entire interface between the cable insulator and the reinforcing insulating layer is completed in a state where the bridging of the reinforcing insulating layer has not yet progressed at the interface, and the end of the bridging proceeds from the center of the reinforcing insulating layer to the end. be able to. By the way , in the course of raising the temperature of the heater sharing the right end and the left end of the connection portion, the heater sharing the right end and the left end is set so that the interface between the cable insulator and the reinforcing insulating layer has a temperature higher than the melting point of the reinforcing insulating layer. 100 ° C. to 130 DEG ° C. as the temperature to be maintained is desired. In the present invention, as described above, a target for bridging a heater sharing the center of a connecting portion of a plurality of divided heaters along the longitudinal direction of the connecting portion for bridging. The time to reach the temperature is at least three hours ahead of the time to reach the target temperature for the bridge of the heater sharing the right end and the left end of the connection portion , during which the heat sharing the right end and the left end.
The interface between the cable insulator and the reinforcing insulation layer is
Ru is maintained at a temperature such that the temperature above the melting point of the layer.
For this reason, in the course of raising the temperature of the heater that shares the right end and the left end of the connection portion, the temperature of the heater is lower than the target value for cross-linking, at a temperature higher than the melting point of the reinforcing insulating layer, or at the melting point temperature. Hold for a certain time. Here, in order to uniformly fuse the reinforcing insulating layer and the cable insulator everywhere,
The temperature of the heater sharing the center of the thick reinforcing insulating layer must be raised quickly, and after the central portion has been fused, the thin ends of the reinforcing insulating layer must be fused. At least two hours or more are required to maintain the heaters sharing the right and left ends of the connecting portion at a temperature lower than the target temperature for cross-linking. Before this, the crosslinking at both ends proceeds. FIG. 3A shows an example of the temperature history at the time of increasing the temperature of the cross-linking in the method of the present invention and the conventional method (when a plurality of divided heaters are simultaneously turned on and the time to reach the target temperature is the same). In the figure, open circles and open triangles indicate the temperature history of the method of the present invention, solid circles and closed triangles indicate the temperature history of the conventional method, and open circles and solid circles indicate the interface of the flat central portion of the cable insulator [FIG. ), White triangles, and black triangles indicate the temperature history of the interface at the pencil shoulder (shoulder of the portion where the cable insulator is tapered: point B in FIG. 3B). . From the figure, it can be seen that the temperature at the center of the flat portion is higher than the temperature at the shoulder portion of the pencil in the initial stage of the temperature rise. However, when the heating method of the present invention is used, the temperatures are reversed below the melting point of the resin. I have. On the other hand, in the conventional method, those temperatures are reversed above the melting point. That is, since the temperature at the center of the flat portion rises first and the temperature at the shoulder portion of the pencil follows later, it melted from the end of the reinforcing insulating layer. Therefore, residual gas existing at the interface between the reinforcing insulating layer and the cable insulator is left at the interface as it is, and microvoids are generated at the interface. An embodiment of the method for cross-linking a connecting portion reinforcing insulating layer of the present invention will be described below. First, the two cables to be connected are peeled off at each step, the exposed conductor is connected, and the inner semiconductive layer is applied. Then, a mold for extruding uncrosslinked polyethylene is installed, and the above-mentioned inside of the extrusion mold is set. An extruder was used to fill the semiconductive layer with an uncrosslinked polyethylene as a reinforcing insulating layer using an extruder. After extruding the uncrosslinked polyethylene, the extrusion mold is removed, the reinforcing insulating layer is cut and shaped into a predetermined shape, and then, while being externally pressurized with nitrogen gas or the like, the connecting portion at both ends 1/6 along the longitudinal direction of the connecting portion. And the center 2/3 was heated by the heater which shared the length direction mutually. FIG. 1 is a view showing a state in which a heater divided into three as described above is mounted on a reinforcing insulating layer, and a bridge tube is mounted. FIG. 1 shows a cross-sectional structure of an upper half of a cable connection portion. Is shown. In the figure, 1 is a cable insulator, 2
Is a reinforcing insulating layer, 3 is an outer semiconductive layer, 4 is an inner semiconductive layer,
Reference numeral 5 denotes a conductor connecting pipe, 6 denotes a cross-linking pipe, and 7 denotes a protective layer. The inside of the cross-linking pipe 6 is filled with nitrogen gas and pressurized. H1 to H3 are heaters, and the heaters H1 to H3 are divided into three portions for heating the center, the left end, and the right end of the cable connection portion. FIG. 2 is a diagram showing a connection mode between the heater and the temperature control device. As shown in FIG.
Heaters H1 to H for heating the center, right end and left end
Sensors S1 to S3 for measuring the temperature of No. 3 were attached, and the leads from the sensors S1 to S3 and the heaters H1 to H3 were drawn out through the bridge tube 5, and connected to the temperature controllers Cn1 to Cn3. Temperature controllers Cn1 to Cn3
Are based on the detection outputs of the sensors S1 to S3,
The temperatures 1 to H3 are controlled in a predetermined temperature pattern. In this embodiment, of the heaters H1 to H3, the time to reach the target temperature for bridging the heater H2 for heating the central portion of the reinforcing insulating layer 2 is determined by the right and left ends of the reinforcing insulating layer 2. Of the heaters H1 and H3, which are used for heating, were advanced by 3 hours or more from the time when the temperature reached the target temperature for crosslinking. Further, a heater H for heating the right end and the left end of the reinforcing insulating layer 2 is provided.
In the course of raising the temperature of H1 and H3, the temperature of the heaters H1 and H3 is set to a constant value so that the temperature of the reinforcing insulating layer 2 is equal to or higher than the melting point of the reinforcing insulating layer 2 and equal to or lower than the temperature at which crosslinking does not proceed. Held. The control temperature of the heater H2 for heating the central portion of the reinforcing insulating layer 2 is, for example, 220 °
The control temperature for the bridge of the heaters H1 and H3 for heating the right end and the left end is 180 °, for example. FIG. 4 shows the temperature control conditions in this embodiment.
FIGS. 5A to 5C show, as comparative examples, temperature control conditions in the case where the present invention is applied under conditions deviating from the conditions of the present invention. 4 and 5, the conditions other than the temperature control conditions were the same. 4 and 5
, The thick line indicates the temperature of the heater that heats the center of the reinforcing insulating layer, the dotted line indicates the temperature of the heater that heats the right and left ends of the reinforcing insulating layer, the horizontal axis indicates time, and the vertical axis indicates the temperature. It is. An interface between the cable insulator and the reinforcing insulating layer is cut out from the position shown in FIG. 1A from the mold connection portion constructed under the temperature control conditions shown in FIGS. 4 and 5, and voids at the interface are observed with a 400 × optical microscope. , An area of 25 mm 2 , and the presence or absence of voids at the interface. Table 1 is a table showing the presence / absence of voids in the mold connection portion constructed under the temperature control conditions of FIGS. 4 and 5. The following is clear from Table 1. [Table 1] In the first to third embodiments, as described above, the time to reach the target temperature for bridging the heater H2 for heating the central portion of the reinforcing insulating layer 2 is determined by the right and left ends of the reinforcing insulating layer 2. Of the heaters H1 and H3, which are used for heating, were advanced by 3 hours or more from the time when the temperature reached the target temperature for crosslinking. Further, a heater H for heating the right end and the left end of the reinforcing insulating layer 2 is provided.
In the course of raising the temperature of H1 and H3, the temperature of the heaters H1 and H3 is set to a constant value so that the temperature of the reinforcing insulating layer 2 is equal to or higher than the melting point of the reinforcing insulating layer 2 and equal to or lower than the temperature at which crosslinking does not proceed. Held. As a result, no void was generated at the interface as shown in Table 1. This is probably because the fusion of the entire interface between the cable insulator and the reinforcing insulating layer progressed uniformly and sufficiently before the bridging of the right end portion and the left end portion of the reinforcing insulating layer 2 progressed, and then the bridging progressed. On the other hand, in Comparative Examples 1 to 3 in FIG. 5, voids occurred at the interface between the cable insulator and the reinforcing insulating layer . In Comparative Example 1, since the heater H2 for heating the edge of the reinforcing insulating layer was quickly raised, the time to reach the target temperature for crosslinking was earlier, and voids were generated in the central portion of the reinforcing insulating layer. It is considered something. In Comparative Example 2, when the heaters H1 and H3 for heating the right and left ends of the reinforcing insulating layer were kept constant during the temperature rise, the temperature to be held was too low. It is considered that voids were generated due to insufficient fusion of the interface at the portion. For Comparative Example 3, the right end of the reinforcing insulating layer
When the heaters H1 and H3 for heating the left end portions are kept constant during the heating, the holding temperature is too high. Therefore, before the fusion of the interface at the center of the reinforcing insulating layer proceeds,
It is considered that voids were generated because fusion of the right and left ends of the reinforcing insulating layer proceeded. In the above-described embodiment, the case of the EMJ-type mold connection portion has been described. However, the same effect can be expected when the BMJ-type is used. As described above, in the present invention,
Since the cross-linking can proceed after the cable insulator and the reinforcing insulating layer interface are uniformly fused, almost no voids are generated at the interface, and a mold connection with excellent electrical properties can be constructed. Its industrial utility value is extremely large.
【図面の簡単な説明】
【図１】本発明における架橋方法を説明する図である。
【図２】本発明におけるヒータと温度制御装置との接続
態様を示す図である。
【図３】本発明の方法と従来方法における架橋昇温時の
絶縁補強層とケーブル絶縁体の界面の温度履歴の一例を
示す図である。
【図４】本発明の実施例１〜３の温度制御条件を示す図
である。
【図５】比較例の温度制御条件を示す図である。
【図６】ケーブル接続部の構造を示す図である。
【符号の説明】
１ ケーブル絶縁体
２ 補強絶縁層
３ 外部半導電層
４ 内部半導電層
５ 導体接続管
６ 架橋管
Ｈ１〜Ｈ３ ヒータ
Ｓ１〜Ｓ３ センサ
Ｃｎ１〜Ｃｎ３ 温度制御器BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a crosslinking method in the present invention. FIG. 2 is a diagram showing a connection mode between a heater and a temperature control device according to the present invention. FIG. 3 is a diagram showing an example of a temperature history at an interface between an insulating reinforcing layer and a cable insulator at the time of raising the temperature of crosslinking in a method of the present invention and a conventional method. FIG. 4 is a diagram showing temperature control conditions of Examples 1 to 3 of the present invention. FIG. 5 is a diagram showing temperature control conditions of a comparative example. FIG. 6 is a diagram showing a structure of a cable connection unit. [Description of Signs] 1 Cable insulator 2 Reinforced insulating layer 3 Outer semiconductive layer 4 Inner semiconductive layer 5 Conductor connection pipe 6 Bridge pipes H1 to H3 Heaters S1 to S3 Sensors Cn1 to Cn3 Temperature controller
フロントページの続き (56)参考文献 特開 昭60−221983（ＪＰ，Ａ) 特開 平５−122819（ＪＰ，Ａ) 特開 平４−368410（ＪＰ，Ａ) 特開 平５−64334（ＪＰ，Ａ) 特開 平９−9448（ＪＰ，Ａ) 実開 昭61−48680（ＪＰ，Ｕ) (58)調査した分野(Int.Cl.7，ＤＢ名) H02G 15/08 H02G 1/14 Continuation of the front page (56) References JP-A-60-221983 (JP, A) JP-A-5-122819 (JP, A) JP-A-4-368410 (JP, A) JP-A-5-64334 (JP) , A) JP-A-9-9448 (JP, A) Japanese Utility Model Application Showa 61-48680 (JP, U) (58) Fields studied (Int. Cl. 7 , DB name) H02G 15/08 H02G 1/14
Claims (1)
を加熱し架橋させる工程において、 架橋を行う接続部の長手方向に沿って複数に分割された
ヒータの制御において、接続部中央を分担するヒータの
架橋のための目標温度に至る時刻を、接続部の右端と左
端を分担するヒータの架橋のための目標温度に至る時刻
より３時間以上先んじさせ、その間、前記右端と左端を
分担するヒータをケーブル絶縁体と補強絶縁層の界面が
上記補強絶縁層の融点より高い温度になるような温度に
維持させることを特徴とする架橋ポリエチレンケーブル
のモールド接続部補強絶縁層の架橋方法。(57) [Claim 1] In the step of heating and cross-linking a cable connection portion on which a reinforcing insulating layer is formed, a plurality of heaters divided along a longitudinal direction of the connection portion to be cross-linked are provided. In the control, the time to reach the target temperature for bridging the heater sharing the center of the connection is set at least three hours ahead of the time to reach the target temperature for bridging the heater sharing the right and left ends of the connection. And reinforcing the heater connecting the right end and the left end to a temperature at which the interface between the cable insulator and the reinforcing insulating layer is higher than the melting point of the reinforcing insulating layer. How to crosslink the insulating layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30551797A JP3469759B2 (en) | 1997-11-07 | 1997-11-07 | Method of cross-linking reinforcing insulation layer at mold connection of cross-linked polyethylene cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30551797A JP3469759B2 (en) | 1997-11-07 | 1997-11-07 | Method of cross-linking reinforcing insulation layer at mold connection of cross-linked polyethylene cable |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11146550A JPH11146550A (en) | 1999-05-28 |
| JP3469759B2 true JP3469759B2 (en) | 2003-11-25 |
Family
ID=17946114
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30551797A Expired - Fee Related JP3469759B2 (en) | 1997-11-07 | 1997-11-07 | Method of cross-linking reinforcing insulation layer at mold connection of cross-linked polyethylene cable |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3469759B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101720795B1 (en) * | 2010-03-16 | 2017-04-03 | 엘에스전선 주식회사 | Inner-Semiconductive Layer Molding Device for High-Voltage Power Crosslinked Polyethylene Insulated Vinyl Sheathed Cable and Inner-Semiconductive Layer Structure Using The Same |
-
1997
- 1997-11-07 JP JP30551797A patent/JP3469759B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11146550A (en) | 1999-05-28 |
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