The Siemens 3RT1044-1AP60 is a SIRIUS S3 power contactor built for motor switching in control panels. It carries a 37 kW rating at 500 V AC-3 and 18.6 kW at 690 V AC-3, which covers the common 400 V and 690 V industrial motor loads in Europe and export machinery. The screw-type terminals on the main circuit accept up to 50 mm² stranded cable, so it lands on the BOM for 30–37 kW pump, fan, and conveyor drives without needing a terminal adapter. Mounting is screw-and-snap-on onto 35 mm or 75 mm standard DIN rail, and side-by-side mounting is permitted — no derating gap required between units in a multi-contactor group. The IP20 front with cover or box terminal keeps live parts behind the panel door, while the terminal block itself is IP00, which is normal for this class.
Sizing and duty-cycle fit
The AC-3 switching rate of 1,000 cycles per hour and mechanical life of 10 million operations mean this contactor is sized for continuous production machinery, not occasional start-stop. The AC-4 rate of 300 cycles per hour covers plugging and inching duty where the contactor makes and breaks stalled-rotor current. For a packaging line running 20 cycles per minute, the AC-3 rate gives headroom; for a reversing conveyor section with frequent plugging, the AC-4 rate governs the selection. The 70 mm width matches the S3 frame footprint, so a panel laid out for a 3RT1044-1FB46 or 3RT5044-1BM40 will accept this unit without re-drilling the mounting rail or re-routing the main power cables. The terminal wiring capacities are identical across these S3 variants — solid 2x (0.5–1.5 mm²) and stranded 2x (10–50 mm²) — so the control wiring plan stays unchanged.
Environmental and installation limits
Operating temperature range is -25 to +60 °C, storage -55 to +80 °C. Pollution degree 3 means the contactor is rated for conductive pollution environments typical of industrial enclosures without climate control. The 139 mm depth fits a 200 mm deep enclosure with room for wiring ducts and a 35 mm rail clearance behind the panel door. Coil operating range is 0.8–1.1 x rated voltage at both 50 Hz and 60 Hz, with an arcing time of 10–15 ms and closing time of 10–19 ms. These timing figures matter for coordination with upstream short-circuit protection devices — the contactor clears its arc before a fast-acting fuse element reaches its melting point.