The Siemens SIRIUS 3RT1017-1BA42 is a Size S00 power contactor rated for motor switching at 5.5 kW in AC-3 duty at 400 V, with a 24 VDC coil drawing 3.3 W for both closing and holding.
The AC-3 rating of 5.5 kW at 400 V governs the motor load this contactor can switch under starting conditions — that's the figure to match against your motor nameplate, not the AC-1 resistive rating. For reversing or inching duty (AC-4), the contactor is rated at 8.5 A at 400 V, which is lower than the AC-3 current, so factor that in for jogging or plugging applications. The 24 VDC coil holds at 3.3 W, which is consistent across closing and holding, meaning no inrush spike to size your control transformer around. The screw terminals accept solid or stranded conductors: 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or max 2x 0.75–4 mm² per clamp. For AWG, that's 2x 20–16, 2x 18–14, or 1x 12. The IP20 finger-safe protection on the front and terminals means the contactor can be mounted in a panel without additional terminal shrouds for basic touch protection.
Mounting and coordination
For Type 1 coordination, use a gL/gG fuse rated 35 A; for Type 2 coordination, use 20 A.