The Siemens 3RT1017-1BM42 is a SIRIUS power contactor in the compact S00 frame, rated for 5.5 kW at 400 V in AC-3 duty — that's the switching category for standard squirrel-cage motors, so it handles starting and running currents for a motor load up to that power. The AC-4 rating at 8.5 A at 400 V covers reversing and inching applications where the contactor makes and breaks stalled-rotor current.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022. At 45 mm wide and 57.5 mm tall, it fits a standard 45 mm slot in a panel layout. Side-by-side mounting is allowed, with 6 mm clearance to adjacent devices on the side. The screw-type terminals for the main circuit accept 2x (0.5 to 1.5 mm²) solid, 2x (0.75 to 2.5 mm²), or up to 2x 4 mm² stranded — covers most panel wiring without crimp lugs.