Service System, Electric Power-Plant

the complex of auxiliary electrical equipment in an electric power plant that ensures the uninterrupted operation of the plant’s basic units, such as the steam boilers, turbogenerators, nuclear reactors, or hydroturbines. The service system includes the plant’s electric-power and lighting supplies, battery installations, emergency power supplies, the electric motors of all the mechanisms (water, crude-oil, and lubrication pumps), and blowers. In steam power plants, which are the most common type, the service system also includes mechanisms for unloading railroad cars, feeding fuel, and crushing and pulverizing coal.

The power-consuming equipment in the plant’s service system is divided into groups according to the requirements for uninterrupted operation of the plant. The most important group includes equipment whose failure would cause either a disruption of the plant’s normal operating conditions or a breakdown. Such equipment consists of the boiler feed pumps in a steam power plant, the reactor control and protection systems and cooling shutdown mechanisms in a nuclear power plant, and the mechanisms that provide for the circulation of oil and water in the lubrication and cooling systems and the mechanisms for closing the butterfly valves in the penstocks in hydroelectric power plants. The operation of the equipment is organized in such a way as to provide redundancy, which ensures high reliability for the power plant’s service system. The electric power required to operate a plant’s service system ranges from 0.2 percent of the total electric power generated by a large hydroelectric power plant to 12 percent of the power generated by a nuclear power plant using gas as a heat-transfer agent.