Discharges and Streamers Properties in Dielectric Liquids under Various Temperature

This paper presents partial discharges and streamers characterizations on 3 dielectric liquids under variation of wide temperature range, i.e.: aromatic hydrocarbon dibenzyltoluene, synthetic ester and halogenic perfluoropolyether liquids. Results indicate distinct behaviors among these liquids under highly divergent AC sinusoidal and impulse electric field. Dibenzyltoluene demonstrates excellent feature in suppressing discharges even at elevated temperature. In synthetic ester, positive discharges appeared to be less numerous but extremely high up to several nC in amplitude are strongly related to the further breakdown. Streamers inception voltage which denotes the initial discharges properties and streamer propagation velocity varies from several m/s up to order of km/s, show less dependency to temperature instead of the intrinsic characteristic of liquid itself. These prebreakdowns phenomena constitute interesting information in planning and selecting insulation liquids and analyzing fundamental mechanism during the operation and maintenance for HV utility applications.