ABSTRACT
Distribution is the last section of the electrical power system. Figure 7.1 shows the major components of the
electric power system. The power plants convert the energy stored in the fuel (coal, oil, gas, nuclear) or hydro
into electric energy. The energy is supplied through step-up transformers to the electric network. To reduce
energy transportation losses, step-up transformers increase the voltage and reduce the current. The high-
voltage network, consisting of transmission lines, connects the power plants and high-voltage substations in
parallel. The typical voltage of the high-voltage transmission network is between 240 and 765 kV. The high-
voltage substations are located near the load centers, for example, outside a large town. This network permits
load sharing among power plants and assures a high level of reliability. The failure of a line or power plant will
not interrupt the energy supply.
