The Siemens SIRIUS 3RA2318-8XB30-1BB4 is a reversing contactor assembly — a pre-wired pair of contactors with mechanical interlock, so one motor can run forward and reverse without external wiring. It ships with two 3RT2018-1BB42 contactors already mounted and interlocked. The 24 VDC coil keeps control voltage low-voltage for safety circuits. Size S00 means a compact footprint — 90 mm wide, 68 mm tall, 73 mm deep — and it snaps onto a 35 mm DIN rail or screws directly to a backplate.
At 480 V it's rated 14 A; at 600 V, 11 A. Coil is screw-type terminals, same as the main circuit. Wire range accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid or stranded — covers standard panel wiring without adapters. For reversing duty where the contactor cycles direction under load, the AC-3 maximum switching rate is 750 operations per hour.
The 90 mm width matches the S00 contactor footprint, so it fits alongside other SIRIUS components in a uniform row. Clearance: 6 mm upwards, forwards, downwards, and to the side; 0 mm backwards (flush to the rail). The shock/vibration ratings (11.4 g at 5 ms, 7.3 g at 10 ms for both AC and DC) confirm it's suitable for machine-mounted applications with moderate vibration.