Partial dischargesdetection inmedium voltage systems usingdirectional antenna sensors
A. Cavallinil, G. C. Montanaril, Roberto Gagliano Candela, L. Testa · 2008
Partial discharge (PD)measurement isafundamental tool toevaluate thestate ofapparatuses ofmediumvoltage (MV) powersystems. An alternative totraditional PD sensors (e.g. currenttransformers, capacitive couplers) for online measurements canbeconstituted partly byelectromagnetic field sensors, capable topickupthesignals generated byPDoccurring intheinsulation system andtraveling inthesurrounding media. Inthis paper, theresults ofon-line PDmeasurements, performed ontwoPILCMV powerlines bymeansofaUWB PD detector andanarrowbandlogperiodic antenna sensor, arepresented andcommented. Thesensorwaschoseninorderobtain the maximumsensitivity onthebasis ofthefrequency content ofthe input signal (i.e. electromagnetic pulse generated byPD)andto giveanoptimized outputsignal according tothePD detector characteristics (such asinputimpedance andbandwidth). The results oftheon-field tests showthatthesystem composed bythe PD detector andtheantennasensorisabletodetect PD occurring incable accessories. Rejection ofnoise andofexternal disturbances isalsopossible by meansoftime-frequency mapping ofrecorded pulses. Thecorrect identification ofthePD phenomenon andtheconsequent riskassessment canthusbe performed. Theusedantenna sensor isdirectional andallows localized investigation oneachcomponent ofthesystem tobe performed andinformation aboutthePD source location tobe gathered.