Siemens 3RT1044-1AP04-3MA0 — SIRIUS Size S3 Power Contactor
The Siemens 3RT1044-1AP04-3MA0 is a SIRIUS-branded power contactor in Size S3, designed for switching motor loads in control panels and industrial machinery. Its AC-4 rating of 55 A at 400 V governs plugging and inching duty — the most demanding switching category for contactors, where the motor is reversed or stopped by counter-torque. The AC-2 rating of 30 kW at 400 V covers slip-ring motor starting and braking. Mounts via screw and snap-on onto 35 mm or 75 mm standard DIN rail, with side-by-side mounting permitted for multi-contactor assemblies in tight panel layouts. The front face carries IP20 protection; the terminal area is rated IP00.
Ratings and What They Mean for Fit
The 55 A AC-4 rating at 400 V is the headline figure for this contactor — it tells you the part can repeatedly switch motor loads under the most severe conditions (plugging, inching, jogging) without exceeding its thermal capacity. For standard AC-3 motor starting (direct-on-line, no counter-torque), the contactor comfortably handles higher currents; the AC-4 limit is the binding constraint for reversing or braking applications. Operating temperature range is -25 to +60 °C during operation, with storage from -55 to +80 °C. The storage range is wider — it governs handling and warehousing, not running conditions. Pollution degree 3 means the contactor is rated for conductive pollution environments typical of industrial control panels. Mechanical endurance is 10 million operating cycles typical, with maximum switching rates varying by duty: 1 000 cycles/hour at AC-1 and AC-3, 400 at AC-2, and 300 at AC-4.
Termination and Wiring
Main current circuit uses screw-type terminals. Solid conductors accepted: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded conductors: 2x (10 to 50 mm²). Solid or stranded: 2x (2.5 to 16 mm²). These terminal ranges cover both control-circuit wiring (smaller gauges) and main power cabling (up to 50 mm² stranded), so the contactor can be wired directly to motor feeders without intermediate terminal blocks.