The Siemens SIRIUS 3RT1017-2AP04-3MA0 is a Size S00 power contactor rated for 5.5 kW at 400 V in AC-2 duty — the standard category for slip-ring motor starting and reversing. Spring-loaded terminals on the main current circuit accept 2x (0.25 to 2.5 mm²) solid or stranded, which matches the wire range for most motor branch circuits at this frame size.
The AC-2 rating at 400 V (5.5 kW) is the figure that governs motor starting for wound-rotor or reversing applications — not the higher AC-1 resistive rating. If your BOM calls for a contactor on a standard squirrel-cage motor, AC-3 duty is the relevant category; this part carries an AC-4 rating of 8.5 A at 400 V, which covers plugging and inching duty cycles. Type 2 coordination (fuse gL/gG: 20 A) and Type 1 coordination (fuse gL/gG: 35 A) are specified — the lower 20 A fuse protects the contactor under short-circuit conditions so it remains functional after a fault, while the 35 A fuse allows the contactor to be replaced after a fault. This gives the panel designer a choice between uptime and fuse economy.
The 45 mm width and 60 mm height fit standard S00 enclosure cutouts. Spring-loaded terminals reduce wiring time compared to screw terminals — strip length is 8 mm for solid or ferruled stranded wire.