The Siemens SIRIUS 3RA2327-8XB30-1AK6 is a reversing contactor assembly — a pre-assembled pair of contactors mechanically and electrically interlocked to reverse a three-phase motor without external wiring. It ships with one supplied contactor (3RT2027-1AK60) and includes the second contactor in the assembly; the reversing function is built in, so you land the motor leads and control wires directly. Rated at 27 A at 480 V and 15 kW at 400 V (AC-3 duty), it handles typical induction motor loads up to that current — think conveyors, pumps, or fans that need forward/reverse control. The AC-3 rating matters because it reflects switching of starting currents (typically 6–8× FLA) without welding the contacts. The assembly is size S0, which means it fits the standard S0 mounting footprint on 35 mm DIN rail. Screw-type terminals on both the main circuit and the coil simplify wiring with solid or stranded conductors: 2x (1 … 2.5 mm²) and 2x (2.5 … 10 mm²) for the power side, and 2x (0.5 … 1.5 mm²) or 2x (0.75 … 2.5 mm²) for the control side.
Mounting is straightforward: screw or snap onto 35 mm DIN rail. Clearance requirements: 6 mm upwards, forwards, downwards, and to the side; zero clearance backwards (the DIN rail provides that). Vibration resistance: 15 g / 5 ms (DC).
Mechanical endurance and switching frequency
Maximum switching frequency under AC-3 duty is 750 operations per hour (also 750/h for AC-3e). That's sufficient for most reversing applications — a conveyor reversing every few seconds, for example, stays well within this envelope.