The book discusses the issues studied by the disciplines "Power Supply" and "Electrical Networks and Systems." Problems of electric power industry, maintenance, design and arrangement of power supply systems are highlighted, in particular, determination of design loads, calculation of supply and distribution electric networks, calculation of short-circuit currents, voltage regulation, reactive power compensation, structural and circuit solutions of electrical equipment and substations, quality of electric power, rational use of electric power. Almost in each section there are examples of solutions to the problems considered in the theoretical part.