REJ603 Self-Powered Feeder Protection

REJ603 relay is intended to be used for the selective short-circuit and earth-fault protection of feeders in secondary distribution networks and for protection of
transformers in utilities and industies. The relay is a self-powered Numerical relay, which does not requires external auxiliary supply voltage, making it an ideal
choice for installation even in remote locations where auxiliary supplies are not
available. The relay derives power for its operation from the current transformers.
REJ603 is primarily used in Ring Main Units ( RMU ) within distribution network.
Relay provides earth current measurement through internal calculation or has the
provision for measuring it from the external core balance current transformer (CBCT).
Self-powered three phase non-directional overcurrent and earth-fault protection with DMT and IDMT characteristics
Dual mode of earth fault measurement – internal vector summation or external
CBCT input
Integrated IDMT curves (IEC and Special) in a single product to cover time coordination needs of secondary distribution protection
Protection blocking by second harmonic measurement for stability during
magnetizing inrush of transformers
Capacitor discharge impulse output for low energy trip coil
Built-in hand-reset electromechanical Flag for trip indication
Easy setting by DIP switches, protected by a transparent cover
Compact design and mounting arrangement suitable for Ring Main Unit (RMU)
applications
Test facility for testing entire scheme including primary CT, relay, and trip coil

REJ603

The combined overcurrent and earth-fault relay is a secondary relay to be connected
to the current transformers of the protected object. Apart from the measurement
(inputs), the relay derives energy required for its own operation and tripping of circuit
breaker from the current transformers. There are two LED’s on the front panel. When
minimum current required for operation is available the green ‘Ready’ LED glows
indicating the relay is in operation. On detection of a fault the relay trips the circuit
breaker in accordance with the settings. The relay also does internal health check
at regular interval and intimates user in case of any internal relay failure. The internal
relay failure is indicated by red ‘IRF’ LED. .
When the phase current exceeds the set operate time at definite time operation or
the calculated operate time at inverse time operation elapses, the overcurrent unit
operates. In the same way the high-set stage I>> of the overcurrent unit operates
when the set operate time elapses.
When the earth-fault current exceeds the set operate time at definite time operation
or the calculated operate time at inverse time operation elapses, the earth-fault unit
operates. In the same way the high-set stage I0>> of the earth-fault unit operates
when the set operate time elapses.