Streamer propagation in small gaps of synthetic ester and mineral oil under lightning impulse

Streamer Propagation and Breakdown in a Very Small Point-Insulating Plate Gap in Mineral Oil and Ester Liquids at Positive Lightning Impulse Voltage

“…Despite many positive features of the esters, the studies concerning streamer propagation and breakdown under lightning impulse (LI) voltage have indicated that esters may behave worse than mineral oils at such types of voltage stresses [13][14][15][16][17]. Because the number of the studies in this field is still limited, and knowledge is still regarded as insufficient to clearly determine which of the liquids (esters or mineral oils) behave better under LI stresses and why, the authors' studies have only been focused on the above-mentioned aspect and are presented in this paper in terms of a very short (10 mm) point-plate gap.…”

“…In contrast to the majority of published works [13][14][15][16][18][19][20][21], the author used an insulating plate placed on the grounded electrode. This allowed for closer alignment of the electrode system tested with real systems, where the inhomogeneity caused by the point electrode may constitute a place of locally increased intensity of the electric field stress and where the discharge develops only from this point to the electrode, which is usually insulated [17,22,23].…”

“…The commonly adopted approach in the assessment of esters is based on the comparison of ester features with features of mineral oil registered in the same testing conditions [2][3][4][8][9][10][11][13][14][15][16][17]. Among the features of the streamers developing in dielectric liquids, the most important are the streamer shapes, currents, and light waveforms, as well as propagation velocity.…”

“…However, the moment of the appearance of fast streamers with an increase of testing voltage is also connected with the type of liquid in which the streamers develop. Ionization and excitation of the molecules in the given liquids are the molecular structure-dependent processes [13][14][15][16][17][18][19][20][21][22].…”

“…If breakdown takes place within the development of fast streamers, the energy of the breakdown channel is also much higher than the corresponding energy of the breakdown channel being a result of development of slow propagating streamers. Thus, the observation of pre-breakdown and breakdown phenomena for different dielectric liquids in the same testing conditions may allow for the assessment of the differences and similarities between them [14,15,17].…”