The article describes factors affecting changes of physical parameters of plasma in a column and in near-electrode areas of arc in electro-technological devices. The article also presents the effect of chemical composition and of temperature on the non-linearity of selected characteristics of plasma-creating gases. In addition, the study concerns the effect of the heterogeneity of electrode materials on the non-linearity and parametrisation of near-electrode voltage drops, taken into consideration in the approximation of static characteristics of an arc column. The article also presents selected linear and non-linear models of electric arc columns. Research-related simulation results, in the form of non-linear dynamic characteristics of electric arcs, were highly consistent with experimental data.