報告書番号

W88046

タイトル（和文）

合成レジン絶縁発電機巻線の絶縁劣化判定法

タイトル（英文）

AN LNSULATION DIAGNOSTIC METHOD FOR GENERATOR STATOR WINDINGS USING MICA-RESIN INSULATION SYSTEM.

概要 （図表や脚注は「報告書全文」に掲載しております）

合成レジン絶縁発電機巻線の絶縁診断に必要な劣化判定基準の確率を目標として，加速劣化モデルコイル，実機巻線およびサンプリングコイルの非破壊絶縁特性と絶縁破壊電圧ＶＲとの相関データを調査，収集し，以下の結果を得た。（１）ＶＲは経年的に低下し，とくに使用年数２０年を過ぎると低下速度が増加する傾向が生じる。したがって，レジン絶縁発電機巻線は絶縁診断を定期的に行い，絶縁破壊事故の未然防止を図る必要がある。（２）ｑｍ（最大放電電荷），Ｎｑ（ｑｍ－Ｖ特性の傾き）および△ｔａｎδとＶＲとの間に良好な相関関係がみとめられた。しかし，△Ｉ（交流電流増加率）とＶＲとの間には相関性がほとんどなく，このため，絶縁劣化判定基準の判定項目をｑｍ，Ｎｑ，および△ｔａｎδの３項目とすることにした。（３）ＶＲが（２Ｅ＋１）ｋＶに相当するｑｍおよびＮｑの値から，次の劣化判定基準の値を決めた。ｑｍ：３×１０４ｐＣ，Ｎｑ：

概要 （英文）

SINCE GENERATOR STATOR WINDINGS ARE USUALLY USED UNDER COMBINED STRESSES OF HIGH VOLTAGE,HIGH TEMPERATURE,HIGH HUMIDITY,HEAT CYCLE,ETC.,COILS OF RESIN-MICA INSULATION TYPE ARE EMPLOYED. THESE RESIN INSULATION WINDINGS HAVE BEEN USED FOR MORE THAN 25 YEARS,AND THEY ARE NOW REACHING THE SERVICE LIFE. EXPECTATIONS ARE,THEREFORE,BEING PLACED ON THE ESTABLISHMENT OF THE CRITERIA WHICH IS NECESSARY TO DIAGNOSE INSULATION DETERIORATION IN THESE WINDINGS. ACCORDINGLY,WITH THE OBJECT OF ESTABLISHING CRITERIA FOR JUDGEMENTS OF DETERIORATION IN RESIN INSULATION WINDINGS,THE AUTHORS CARRIED OUT TESTS ON THE DETERIORATION OF MODEL COILS,ACQUIRED DATA ON THE CORRELATION BETWEEN NON-DESTRUCTIVE MEASUREMENTS AND RESIDUAL BREAKDOWN VOLTAGE VR ON WINDINGS IN OPERATION AND SAMPLING COILS,AND CONDUCTED RELATED INVESTIGATIONS. AS A RESULT,THE FOLLOWING POINTS WERE IDENTIFIED: (1)VR DIMINISHES WITH THE LAPSE OF TIME. PARTICULARY,THERE IS A CONSPICUOUS TENDENCY THAT THE SPEEDOF DIMINUTION INCREAES UPON EXCEEDING ABOUT 20 YEARS OF SERVICE LIFE. IT IS,THEREFORE,NECESSARY TO CONDUCT A PERIODIC DIAGNOSIS OF INSULATIONIN RESIN INSULATION WINDINGS SO AS TO PREVENT AN INSULATION BREAKDOWN ACCIDENT FROM OCCURRING. (2)A RELATIVELY GOOD CORRELATION WAS OBSERVED AMONG QM (MAXIMUM DISCHARGE MAGNITUDE),NQ (INCLINATION OF QM-V CHARACTERISTIC), DELTA TAN DELTA AND VR,BUT LITTLE CORRELATION WAS RECOGNIZED BETWEEN DELTA 1(AC CURRENT INCREASE RATIO) AND VR. AS DIAGNOSTIC ITEMS, THEREFORE,THE FOLLOWING THREE ITEMS WERE ADPTED:QM,NQ AND DELTA TANDELTA . (3) AS THE CRITERIA FOR JUDGEMENTS OF DETERIORATION,THE FOLLOWING VALUES WERE INTRODUCED RESPECTIVELY: QM=3 104PC,NQ=2.0. MEANWHILE, DELTATAN DELTA WAS CHOSE TO BE THE SAME AS A CRITERION VALUE (DELTA TAN DELTA=6.5%) FOR JUDGEMENTS OF DETERIORATION IN THE COMPOUND INSULATED WINDINGS. THE AUTHORS WISH TO APPLY THESE CRITERIA TO THE WINDINGS IN OPERATION IN THE FUTURE.

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