An electric power system is a network of electrical components deployed to supply, transfer, and use electric power. An example of an electric power system is the network that supplies a region’s homes and industry with power—for sizeable regions, this power system is known as the grid and can be broadly divided into the generators that supply the power, the transmission system that carries the power from the generating centres to the load centres and the distribution system that feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings and homes. The majority of these systems rely upon three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialised power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles.
Electric power systems are comprised of components that produce electrical energy and transmit this energy to consumers. A modern electric power system has mainly six main components: 1) power plants which generate electric power, 2) transformers which raise or lower the voltages as needed, 3) transmission lines to carry power, 4) substations at which the voltage is stepped down for carrying power over the distribution lines, 5) distribution lines, and 6) distribution transformers which lower the voltage to the level needed for the consumer equipment. The production and transmission of electricity is relatively efficient and inexpensive, although unlike other forms of energy, electricity is not easily stored, and thus, must be produced based on the demand.