SIRIUS S3 power contactor — 37 kW at 500 V AC-3
The Siemens 3RT1044-1AN20 is a SIRIUS S3 power contactor rated for 37 kW at 500 V in AC-3 duty, meaning it handles motor switching loads up to that power level. It uses screw-type terminals on the main current circuit and mounts via screw or snap-on onto 35 mm or 75 mm standard DIN rail. The contactor carries a mechanical life of 10,000,000 cycles typical, and its AC-3 switching rate maxes out at 1,000 operations per hour. Side-by-side mounting is permitted, which helps when packing multiple contactors into a tight panel row. Operating temperature spans -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 means it's rated for industrial environments with conductive pollution — standard for an unprotected panel installation.
Terminal capacity and wiring
Solid wire accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded wire handles 2x (10 to 50 mm²). The combined solid-or-stranded range covers 2x (2.5 to 16 mm²). These are the wire sizes the screw terminals are designed for — no ferrule adapters needed for the larger strands. Front protection is IP20 with the cover or box terminal installed; the terminal itself is rated IP00. That means the wiring compartment needs enclosure protection in the panel, but the operator-facing side is touch-safe once the cover is on.
Coil and auxiliary contact ratings
The auxiliary contact block (integrated or add-on) is rated for switching at various control voltages: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, and 3 A at 400 V. These are the make/break capacities for the control circuit — useful when selecting a PLC output or relay to drive the coil. Operating time at AC is 10 to 19 ms, with arcing time between 10 and 15 ms. The contactor is rated for both 50 Hz and 60 Hz supply, with operating ranges of 0.8 to 1.1 times nominal at 50 Hz and 0.85 to 1.1 at 60 Hz.