報告書番号

W89018

タイトル（和文）

ＣＶケーブルの半導電層界粗さが絶縁破壊強度に与える影響

タイトル（英文）

INFLUENCE OF INTERFACE ROUGHNESS BETWEEN INSULATION LAYER AND SEMICONDUCTING LAYER ON BREAKDOWN STRENGTH IN XLPE POWER CABLES

概要 （図表や脚注は「報告書全文」に掲載しております）

当所では絶縁厚半減超高圧ＣＶケーブルの開発を行うために添加剤を用いて半導電層界面を改良する，「界面拡散法」を開発した。これをケーブル試料に適用したところ添加剤による効果が少なく，さらに印加電圧の低い外導界面から絶縁破壊が発生することが多いことを突き止めた。そこでその原因を追求すべく内導と外導の界面を電子顕微鏡を用いて詳細に検討した。その結果，製造工程で高い温度履歴を受ける外導界面のμｍオーダーの界面粗さが内導界面のそれよりも５０％程大きく荒れていることが判明した。本報告書は界面粗さの定量化手法と測定結果について述べるともに界面拡散法を実用化する際の問題点と対策について言及したものである。

概要 （英文）

THIS PAPER DESCRIBES THE RELATIONSHIP BETWEEN THE BREAKDOWN STRENGHTH AND THE ROUGHNESS OF THE SEMICONDUCTING INTERFACE IN MODEL XLPE POWER CABLES WITH INSULATION OF 3.5 MM THICKNESS. SEVEN SPECIMEN CABLES WERE MANUFACTURED FROM SEVEN SEMICONDUCTING LAYER MATERIALS AND THEIR IMPULSE BREAKDOWN STREHNGTH WAS MEASURED. SIX ADDITIVES WERE USED TO IMPROVE THE MATERIALS. ONE CABLE SPECIMEN WAS MADE WITHOUT ADDITIVES AS A REFERENCE SPECIMEN. A FEW SPECIMENS SHOWED IMPROVEDIMPULSE BREAKDOWN STRENGTH IN TERMS OF TH 1% IMPULSE WEIBULL STRENGTH.THE MAXIMUM BREAKDOWN STRENGTH OF THE SPECIMENS WAS ABOUT 1.6MV/CM (1%IMPULSE WEIBULL STRENGTH) AND WAS 1.2 TIMES HIGHER THAN THAT OF THE SPECIMEN WITHOUT ADDITIVES. IT WAS FOUND THAT SPECIMENS WITH HIGH BREAKDOWN STRENGTH BROKE DOWN FROM THE INNER SEMICONDUCTING INTERFACE. ON THE OTHER HAND,IT WAS FOUND THAT SPECIMENS WITH LOW BREAKDOWN STRENGTH BROKE DOWN FROM THE OUTER SEMICONDUCTING INTERFACE. SEMICONDUCTING INTERFACE ROUGHNESS ON THE ORDER OF LESS THAN 1MU M WAS QUANTITIZED BY TAKING TRANSMISSION ELECTRON MICROSCOPIC PHOTOGRAPHS OF THE INTERFACE AND DIGITIZING THEM BY COMPUTER. IT WAS FOUND THAT THERE WAS A STRONG CORRELATION BETWEEN THE BREAKDOWN STRENGTH AND THE ROUGHNESS OF THE OUTER SEMICONDUCTING INTERFACE. IT WAS FOUND THAT THE ROUGHNESS OF OUTER SEMICONDUCTING INTERFACE WAS LARGER THAN THAT OF THE INNER INTERFACE. SPECIMENS WITH A LARGE ROUGHNESS VALUES FOR THE OUTER SEMICONDUCTING INTERFACE SHOWED LOW BREAKDOWN STRENGTH. IT WAS CONCLUDED THAT IT IS NECESSARY TO REDUCE THE ROUGHNESS OF THE OUTER SEMICONDUCTING INTERFACE TO INCREASE THEIMPULSE BREAKDOWN STRENGTH OF XLPE CABLES.

報告者

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