The paper presents the Schellhase and Pentegov models utilizing static voltage-current characteristics for representing processes occurring in the electric arc. In the approximations of these characteristics variation in geometrical parameters, i.e. arc length and cross-section is taken into account. A modification of the Voronin-type models is also proposed, introducing a static voltage-current characteristic. In this way, it is possible to take into account distortions of the arc geometrical parameters of the static and dynamic character.