Title :
High stress space charge limited current flow in dielectric oil under ramped voltage application
Author :
Watson, Alan ; Ren, Diana Hua
Author_Institution :
Dept. of Electr. Eng., Windsor Univ., Ont., Canada
Abstract :
A mathematical model for interpreting experimental data obtained from ramped voltage testing of transformer oil is presented. Current is perceived to flow alternately by convection and conduction when the electric field strength is high enough to initiate detrapping of electrons and field dissociation. Homopolar injection of electrons and positive ions is considered to delineate two regimes in which space-charge-limited current is directly related to a simple power of the applied potential. The injection process leads to the launching of solitary waves of the sine-Gordon type from each electrode and detrapping occurs within the wavefront of these. In direct response to this the remaining trapped electrons reorganize into a Beltrami flow field contained within small cells which coincide with the Debye spheres that are pertinent to the electrostatics of the free charge population. These cells act as quasiparticles passing through the dielectric liquid with which they interact to sustain the electrohydrodynamic flow which constitutes their drift motion as carriers in the applied field
Keywords :
electric strength; electrohydrodynamics; electrostatics; insulating oils; insulation testing; space-charge-limited conduction; transformer insulation; Beltrami flow field; Debye spheres; conduction; convection; detrapping; dielectric oil; electric field strength; electrohydrodynamic flow; electrostatics; field dissociation; homopolar injection; ramped voltage application; ramped voltage testing; sine-Gordon type; solitary waves; space charge limited current flow; transformer oil; Dielectrics; Electrodes; Electron traps; Electrostatics; Mathematical model; Oil insulation; Petroleum; Space charge; Stress; Testing;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena, 1990. Annual Report., Conference on
Conference_Location :
Pocono Manor, PA
DOI :
10.1109/CEIDP.1990.201411