TheStudyofNoise-rejection byUsingPulse Time-delay Identification Methodandthe Analysis ofPDDataObtained intheField

Based onthemechanism ofpartial discharges occurring inthestator winding insulations ofgenerators, asetofon-line PDmeasurement withdouble sensors is developed inthis paper. After comparing thedifferent types ofmeasurement, thenoise suppressing method is focused on thetechnique of "pulsetime-delay identification" whichisbasedoninstalling double sensors forevery phase. Theprinciple ofthemethod is introduced inthis paper. Thesoftware program designed byLabview provides thepowerfrequency graph, N-Q andN-('two dimension diagram ,three dimension diagram and maximumquantity ofPD andNQN tendency diagram tomakeafurther analysis ofthePD data. Inaddition, thedadaobtained inthefield isanalyzed here, including aninsulation fault detected inaplant successfully. 1C~~~~~~~~~~AN Bs