Аннотация
The reasonability of the development of general (centralized) short-circuit protection of elements of a 4/3 circuit of open switchgears of power plants and substations is shown. Discriminating elements of a current relay and PDR protection, which receive information from current and voltage transformers, are described. The connection diagram is presented and described. The power directions and current magnitudes in different modes, including SC to earth, are analyzed, as well as the relay behavior. Protection actuation conditions are formulated using the Boolean algebra symbols; they are analytically written and minimized. Special attention is paid to the busbar protection operation algorithms and changing from one current relay setting to another.