A unified theory of uncontrolled rectifiers, discharge lamps and arc furnaces. II. An analog model for educational purposes

This paper describes a new low power analog model conceived for representing three-phase arc furnaces by means of uncontrolled rectifiers and heavy capacitive smoothing. The rest of the arc furnace installation is completed with LC elements taking into account power factor compensation and the effect of the arc furnace transformer taps. Each phase of the nonlinear load can be adjusted independently in order to reproduce harmonics and unbalances generated in arc furnaces. Several experiments are given to teach students about arc furnace aspects including harmonics, unbalances, resonances, measurements, continuous and discontinuous evolution of the AC current, maximal power transfer, etc. The structure of the equipment is modular so that other nonlinear elements: single-phase, three-phase rectifiers and discharge lamps can be represented in systems with three or four wires.