SIRIUS S2 Power Contactor — 24 VDC Coil, Screw Terminals
The Siemens 3RT1035-1BB44 is a SIRIUS power contactor in the S2 frame size, designed for switching motor loads in industrial control panels. The 24 VDC coil pulls in at 0.8 of rated voltage and drops out below that threshold, with an arcing time of 10 to 15 ms at DC and a total break time of 20 to 25 ms. Screw-type terminals on the main circuit accept stranded conductors up to 2x 25 mm², so it handles the feed from a 16 mm² supply cable at 40 °C ambient.
DIN Rail Fit and Panel Integration
Mounts via screw and snap-on onto 35 mm standard rail per DIN EN 50022. The 55 mm width and 112 mm height fit a standard S2 footprint; depth is 179 mm including the coil terminals. Side-by-side mounting is permitted with no derating gap, so you can pack several contactors across a single rail segment. Pollution degree 3 rating means it's suitable for the conductive-dust environment inside a typical panel enclosure.
Switching Capacity and Duty Ratings
Rated for AC-3 motor switching at 500 V delivering 22 kW, and at 690 V delivering 11.4 kW. AC-4 inching duty at 400 V is rated at 35 A. The contactor handles 1 200 operations per hour in AC-1 resistive loads, 1 000 ops/h in AC-3, and 300 ops/h in the heavy AC-4 regime. Mechanical life is 10 million operations typical. Auxiliary contact ratings at 24 VDC are 10 A, dropping to 0.3 A at 220 VDC.