Bus-bar

Article By:

Karady, George G. Department of Electrical Engineering, Arizona State University, Tempe, Arizona.

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.100400

An aluminum or copper conductor supported by insulators that interconnects the loads and the sources of electric power in an electric power system. A typical application is the interconnection of the incoming and outgoing transmission lines and transformers at an electrical substation. Bus-bars also interconnect the generator and the main transformers in a power plant. In an industrial plant such as an aluminum smelter, large bus-bars supply several tens of thousands of amperes to the electrolytic process. A single-line diagram of a typical substation bus-bar system is shown in Fig. 1. The bus-bar distributes the current of the two incoming lines between the outgoing line and the transformer. In this example, bus-bar failure interrupts the load connected to the transformer and the outgoing line. In a large station, the bus-bar failure may affect thousands of customers. The reliability of a system including bus-bars can be improved by using double bus-bars, where the loads automatically switch to the operating bus-bar in case of a fault. The ring bus-bar provides two supply routes for each load, which increases the system fault tolerance. A three-phase system has three bus-bars, which collectively are called a bus. See also: Electric power substation

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