REJ601 is a dedicated feeder protection relay intended for the protection of utility and industrial power systems in primary and secondary distribution networks. The relay provides an optimized composition of protection and monitoring functionality in one unit, with the best performance and usability in its class. Besides the conventional current transformer interface based variant, the relay also supports a variant based on Rogowski current sensors’ analog interface. This helps to obtain a compact medium voltage switchgear equipment size reduc­tion with improved performance and standardization.