The REJ603 relay is used for selective short-circuit and earth-fault protection of feeders in secondary distribution networks, as well as for transformer protection in utilities and industry.

The relay is a self-powered digital relay that does not require an external auxiliary supply voltage, making it ideal even for installations in remote areas where auxiliary power is not available.

The relay operates from a current transformer.

The REJ603 is mainly used in Ring Main Units (RMUs) in distribution networks.

The relay provides earth current measurement by internal calculation, or it can measure earth current from an external core balanced current transformer (CBCT).

The main features of the relay are

Self-powered three-phase non-directional overcurrent and earth fault protection with DMT and IDMT characteristics

Dual earth fault measurement modes – internal vector summing or external CBCT inputs

Integration of IDMT curves (IEC and special) in a single product to meet the time-coordinated requirements of secondary distribution protection

Protection blocking via second harmonic measurement to ensure stability during transformer magnetic surges

Capacitive discharge pulse output for low-energy trip coils

Built-in manual reset electromechanical sign for trip indication

Easy setup via DIP switches, protected by transparent cover

Compact design and mounting for ring main unit (RMU) applications

Test equipment for testing the entire program, including primary CTs, relays and trip coils