This technical article discusses criteria and requirements for designing protection systems for busbars in HV/EHV networks. REB611 is a dedicated busbar protection relay designed for phase-segregated short-circuit protection, control, and supervision of single busbars. The GRB200 can be applied for single, double and ring busbars with or without transfer busbar, one-and-a-half CB (busbar). Busbar Differential Protection Definition: Busbar differential protection is a scheme that quickly isolates faults by comparing currents entering and leaving the busbar using Kirchoff's current law. Current Differential Protection: This protection method connects CT secondaries in parallel and. Busbars in the substation form important link between the incoming and outgoing circuits.