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[Библиогр.: с. 53 (4 назв.)]

Partial discharges (PD) in the porous dielectrics are appeared under effect of high electric field intensity. PDs are not cause of material instant breakdown, but they are cause of accumulation of dielectric local damage. Electrical treeing, which is represents tree-like structures formation, occurred due to increasing of PD concentrations and current pulse amplitude reduces the dielectric strength of materials and initiate breakdown. Treeing is most investigated in polymer dielectrics as a negative effect with following insulating parts failure. Dendrites are growth abnormally fast and having large dimensions in some types of layered solid fuels. Dendrite in the oil shale starts to grow on low intensity, and their propagation rate is considerably higher than in polymers. This effect could be applied for a plasma channel inducing and electric heating of oil shale in pyrolytic conversion technologies. Partial discharges are the reason of dendrites formation in the oil shale as well as in other dielectrics. Presents of PDs is confirmed by typical for this phenomena oscillogram of current flowing through the rock. Distinguishing features of treeing in oil shale is effected by the influence of high temperatures around the plasma channel. Phase convertion with the formation of hydrogen and light hydrocarbons C n H 2 n +2 causes formation of carbonization region with a resistivity of 10-100 Ohm·cm. In the oil shale this phenomena observed even at the stage of dendrites growth, so treeing could be called electrothermal in contrast to the electrical treeing occurring in the polymers.