Siemens 3RQ3018-1AB00 Relay Coupler 24V AC/DC Screw Terminal

The Siemens SIRIUS 3RQ3 series 3RQ3018-1AB00 is an ultra-slim coupling relay (output coupler) with a housing only 6.2 mm wide. It couples and electrically isolates signals between PLC or controller outputs and field loads, protecting the controller's output stage while passing the signal through. It provides one change-over contact (1 CO) with a 6 A thermal current rating, so it drives solenoid valves, contactor coils and similar loads directly. Safe isolation between the control circuit and the auxiliary circuit is rated up to 300 V — no separate isolating amplifier is needed.

This model uses screw-type terminals with a tightening torque of 0.5-0.6 N·m and accepts conductors from 0.25 to 2.5 mm² (AWG 20-14) — the right choice where tools are available and wiring must be firmly fixed yet remain serviceable. The 24 V AC/DC coil operates over a wide 0.8-1.25 × Us range to tolerate supply fluctuation, and a green LED on the front panel gives an immediate read on operating and fault status.

The 93 × 6.2 × 72.5 mm housing snaps onto any standard 35 mm DIN rail in any mounting position and requires 0 mm spacing for side-by-side mounting, so dozens can be packed onto a single rail and cabinet space is used efficiently. Mechanical service life reaches 10,000,000 operating cycles, making this relay well suited to high-frequency switching circuits.