The Siemens SIRIUS 3RT1017-1BB42-ZW96 is a size S00 power contactor with a 24 VDC coil, rated for motor switching up to 5.5 kW at 400 V in AC-2 or AC-3 duty. That means it handles both squirrel-cage motor starting (AC-3) and slip-ring motor reversing (AC-2) at the same power level — a common spec for conveyor or pump panels where you need one contactor to cover both duties. The 45 mm width per pole leaves room for auxiliary blocks and a thermal overload relay in the same row.
At 400 V AC-4 (frequent reversing or inching), the contactor is rated 8.5 A — that's the figure to use if your motor cycles on and off repeatedly, not the higher AC-3 number. The AC-12 rating of 10 A covers resistive loads like heater banks. For higher-voltage applications, it delivers 5.5 kW at both 500 V and 690 V, so it works on 480 V and 600 V class systems without a frame size bump. The coil operates at 0.85 to 1.1 times rated voltage (20.4 V to 26.4 VDC), with a drop-out threshold below 18 V.
Screw-type terminals on the main circuit accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or max 2x (0.75 to 4 mm²) solid/stranded — common for control panel wiring. AWG equivalents: 2x (20 to 16), 2x (18 to 14), 1x 12. The depth of 72 mm and height of 57.5 mm fit standard S00 footprints; allow 6 mm clearance at the side for airflow and tool access. For type 2 coordination (no-weld after short circuit), use a 20 A gL/gG fuse upstream; for type 1 coordination (weld allowed but no fire), a 35 A gL/gG fuse. The contactor has 0 built-in auxiliary contacts — plan for a separate auxiliary block if you need status feedback.