This technical article discusses criteria and requirements for designing protection systems for busbars in HV/EHV networks. Busbars. Busbars in power systems are the location where transmission lines, generation sources, and distribution loads converge. Because of this convergence, short circuits located on or near the busbar tend to have very high magnitude currents. Key highlights Due to its extensive I/O capability, REB670 protects single, double, and triple. A busbar protection is a protection to protect busbars at short-circuits and earth-faults.