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PREFACE
Uninterruptedpowerdeliveryisensuredbyreliablepowerequipmentintheareas
ofelectricitygeneration,transmissionanddistribution,whichareimmanentlyrelated
tohighvoltage.Diagnosticmethodologiesthatarecomprisedofsetsofmeasuring
methodsandsystemsusedtoassesstheconditionoftheseobjectsaswellasthepossi-
bilitiesoftheirfurtheroperationareoffundamentalimportanceinthestrategiesof
operatingelectricaldevicesintheabove-mentionedareas.Withregardtohigh-voltage
electricalpowerequipment,diagnosticinvestigationsmainlyconcerntheinsulation
systems(whicharethemainstructuralelementsofthesedevices).Unavoidableopera-
tionalexposures(whichprimarilyincludetheelectricfieldinhigh-voltageinsulation
systems)arethecausesofpartialdischarges(PDs),whichinitiatedegradationprocess-
esinthedielectricstructures.Partialdischargesinhigh-voltageelectricaldevicesare
themainthreatstotheirfailure-freeoperationandapplytoallgroupsofsuchdevices.
Thelifetimeandenduranceofelectricalhigh-voltageinsulationisdeterminedbyits
integrityandisexpressedbythepresenceofpartialdischarges;thesearethephenom-
enaoccurringintheinternalstructureofdielectricsorontheirsurfacesthatleadto
gradualdegradationsand,ultimately,breakdowns.
Understandingtheunderlyingmechanismsinhigh-voltageinsulationisanactual
researchtopic;itreferstogaseous,solid,andliquiddielectricmaterialsthataresub-
jectedtoallkindsofelectricalstresses(i.e.,withalternatinganddirectvoltageand
causedbypowerelectronicsdevicesandvarioustypesofvoltageswithimpulsewave-
forms).Thekeyproblemsinthefieldofpartialdischargesincluderesearchonthe
mechanismsofthesephenomenaindielectrics(especiallyinsyntheticpolymersin-
tendedforhigh-andultra-high-voltageinsulationsystems)aswellastheissueofiniti-
atingdischargesinuniformandnon-uniformelectricfieldsinhomogeneousandheter-
ogeneousinsulationmaterials.Anotherfieldistheinteractionofdischargesintheir
gaseoussourceswiththesurroundingsoliddielectricandtheeffectsoftheenergy
impactofdischargesonthestructuresofdielectricsandtheirerosiveeffectsthat
graduallyleadtoinsulationbreakdown.Furthertopicsincludethedynamicsofthe
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