Gas Formation in Transient Cavities Undergoing PD Pulse Burst Discharges in Transformer Oils

Abstract

Partial discharges in mineral oils take place in the form of pulse bursts within minute microcavities, which are formed at high-electric field charge injection sites. The lifetime of these transient microcavities is determined by the interval between their creation and their ultimate collapse due to dynamic instability. The vapor pressure within these microcavities has been estimated to be as high as 10 MPa and lately there has been considerable speculation as to the nature and type of gases within these microcavities. Currently, carried out experiments indicate that these gases consist principally of hydrogen, CH 4 (methane), and C2H6 (ethane) with smaller traces of other lower molecular weight hydrocarbons

Simulation on the Conditions Affecting Partial Discharge Initiation in Microbubble Immersed in Dielectric Liquid

“…Another matter to be investigated is the effect of the size of microbubble on E. It is unknown whether there is minimum or maximum bubble size for PD to take place. However, most of the articles or papers are referring to the void as microbubble [13], [23]. In fact, in [13] the size of the microbubble is stated as between 2 -10 µm.…”

“…However, most of the articles or papers are referring to the void as microbubble [13], [23]. In fact, in [13] the size of the microbubble is stated as between 2 -10 µm.…”

“…The geometrical parameters that will be varied are the polar-equator radius ratios as well as the shape of the bubble. Gasses that chosen to fill the microbubble are air, ethane and methane [13].…”