The RDC-3 set of resistors is meant for cooperation with the RCW-3 relay.

Application of the RDC-3 set of resistors ensures proper monitoring of tripping circuits continuity by RCW-3 also when the circuit breaker is open. However, if the “trip” impulse is permanent, the RCW-3 will signal lack of circuit continuity. In such case the LEDs in RDC-3 resistors set light up, informing about persisting tripping impulse.