ESTIMATION METHOD OF COPPER SULFIDE GENERATION STATE OF OIL-FILLED CABLE BY INSULATION OIL ANALYSIS, AND DIAGNOSTIC METHOD OF RISK DEGREE

PROBLEM TO BE SOLVED: To provide a diagnostic method of estimating a sulfide generation state in an oil-filled cable using an insulation oil and estimating a degree of risk of abnormality occurrence of the oil-filled cable based on the sulfide generation state estimated by the method.SOLUTION: An estimation method of a copper sulfide generation state of an oil-filled cable includes: a step 1 of preparing a trend graph showing a change with time of a dissolution amount of copper in oil or dielectric loss tangent and a total amount of combustible gas; a step 2 of preparing a graph showing a relationship between the dissolution amount of copper in oil of an insulation oil collected from the insulation oil before using the oil-filled cable and the oil-filled cable and obtaining the maximum dissolution amount of copper in oil from the value of the maximum dielectric tangent in the past; and a step 3 of obtaining a ratio of the dielectric tangent to the amount of the dissolution copper in oil. The generation state of sulfide copper in the cable is estimated by using the values of steps 1 to 3. In addition, a degree of risk is estimated and diagnosed based on a ratio of the dielectric tangent obtained at the step 3 to the dissolution amount of copper in oil, the reference value of the maximum dissolution amount of copper in oil, and the reference value of the total amount of the combustible gas.SELECTED DRAWING: Figure 5 【課題】絶縁油を用いた油入りケーブル中の硫化銅生成状況を推定し、当該方法で推定された硫化銅生成状況に基づいて、油入りケーブルの異常発生の危険度を評価する診断方法を提供すること。【解決手段】絶縁油を使用した油入りケーブルにおいて、ケーブルから採取した絶縁油について、油中溶解銅量もしくは誘電正接と可燃性ガス総量の経時変化を示すトレンドグラフを作成するステップ１と、油入りケーブル使用前の絶縁油と油入りケーブルから採取した絶縁油の油中溶解銅量と誘電正接の関係を示すグラフを作成し、過去の最大誘電正接の値から最大油中溶解銅量を求めるステップ２と、誘電正接と油中溶解銅量の比を求めるステップ３とを含み、ステップ１〜３の値を用いてケーブル内における硫化銅の生成状況を推定する。また、ステップ３で求めた誘電正接と油中溶解銅量の比、最大油中溶解銅量の基準値及び可燃性ガス総量の基準値をもとに危険度を評価、診断する。【選択図】図５