Elements of a Power System

Abstract

A useful diagram to depict the alternating current (ac) system of a nuclear generating station is the one‐line diagram (OLD).The OLD allows for the simplest representation of the main elements of a typical station and the interconnections among them. This chapter discusses the main elements of a power system that are particularly applicable to understanding the basic electrical configuration of a nuclear power plant. For a three‐phase power system, in order properly represent it in an OLD, the system must be balanced, that is each one of the three phases must carry the same magnitude of current, and the currents must be at 120◦ from each other. The switchyard and associated substation are required to connect the power plant to the transmission grid, but are under the control of the power plant operators. The switchyard and its associated breakers, lines, and components are not considered safety related, though they may be considered important to safety.