The Siemens 3RA2328-8XB30-2BB4 is a SIRIUS reversing contactor assembly — a pre-wired, mechanically interlocked pair of contactors that reverses a three-phase motor's direction by swapping two phases. It ships with two 3RT2028-2BB40 contactors already mounted and interlocked, saving panel-build time and eliminating wiring errors that cause phase-to-phase shorts. The AC-3 rating means it makes and breaks motor starting currents — typically 6–8× full-load current — without excessive contact wear. The coil is 24 V DC, so it integrates cleanly into PLC-controlled panels or safety circuits without an AC coil hum or the need for a separate DC supply for the contactor logic.
This assembly uses the S0 contactor frame size (90 mm wide × 114 mm tall × 107 mm deep) and mounts via screw fixing or snap-on onto 35 mm standard mounting rail. Spring-loaded terminals on the main circuit accept 2× (1 … 10 mm²) solid or 2× (0.5 … 2.5 mm²) stranded conductors — no torque screwdriver needed, just strip to 10 mm and push in. The coil connection uses spring-type terminals as well, consistent with the rest of the assembly. Clearance requirements: 6 mm upwards, forwards, downwards, and to the side; 0 mm backwards against the mounting surface. That 0 mm rear clearance means it can sit flush against a back panel or subplate without derating.