The measurement of charge on single particles in transformer oil

Crater Formation on Electrodes during Charge Transfer with Aqueous Droplets or Solid Particles

“…Although similar light flashes have been previously observed when charged objects [13,14] or liquid drops [26] approached an electrode, recent workers have assumed that electrically bouncing droplets are charged via electrochemical reactions not involving dielectric breakdown [18,19]. It is known from previous work that application of an arc current on the order of 1-100 amps between stationary electrodes through vacuum can melt the electrodes via Joule heating, with the high pressure present in the plasma jet of the arc pushing the molten material to form micron-scale craters [27,28].…”

Experimental studies of influence of DC and AC electric fields on bridging in contaminated transformer oil

“…Initially the current is small, but since more and more fibers get an electric charge the current increases until it reaches a saturation which is different for different voltages and particles size. Previously this phenomenon has been investigated by several researchers [8,11,[17][18][19][20][21][22][23] with conductive and dielectric particles. They have calculated the amount of charge acquired by both conductive and dielectric particles.…”

Partial discharge study in transformer oil due to particle movement under DC voltage using the UHF technique

“…Some literature is available dealing with particle initiated breakdown in transformer oil under AC and DC voltages [4,5] but further research is essential to understand the polarity of the applied voltage on partial discharge formation due to particle movement. Birlasekaran has studied particle movement in transformer oil under AC and DC fields both theoretically and by experimental study [6,7]. He concludes that under DC voltages, conductive particles transport charge by contact with electrodes and observed the discharge current in the form of a fast rising current pulse and slowly increasing displacement current [7].…”