The Siemens 3RT1044-1AF00 is a SIRIUS S3-frame power contactor, screw-type terminals on the main circuit, rated for motor switching at 30 kW in AC-2 duty at 400 V — that's the slip-ring motor or wound-rotor load where starting current stays moderate. For AC-4 duty (plugging, inching, reversing) it handles 55 A at 400 V, so it takes the high-stress cycles of frequent reversals without derating prematurely. Snap-on mounting onto 35 mm or 75 mm standard DIN rail, with screw fixing as backup. The S3 frame is 70 mm wide, 146 mm tall, 139 mm deep. Rated for 50 Hz operation, with a rated control supply voltage of 110 V at 50 Hz. Coil draws 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V — the 110 V coil variant means you run it off a standard control transformer without an extra DC supply.
Termination and wiring — screw terminals, stranded up to 50 mm²
Accepts stranded conductors up to 2x 50 mm² — enough for the full AC-2 current without paralleling. Solid wire range is 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). The terminal rating is IP00, so the connection point itself is not sealed — the IP20 rating on the front with cover or box terminal is what protects the operator. Side-by-side mounting is allowed — no derating gap required for adjacent contactors on the rail, which saves panel width when grouping multiple motor starters.