The Siemens SIRIUS 3RT1034-1DB44-0KV0 is a size S2 power contactor with a 24 VDC coil, rated for AC-3 motor switching at 500 V to 18.5 kW and AC-4 at 400 V to 29 A. It mounts via screw and snap-on onto 35 mm DIN rail per EN 50022, with a footprint of 55 mm wide by 112 mm tall by 179 mm deep.
Ratings and what they mean for fit
The AC-3 rating of 18.5 kW at 500 V governs motor starting — this is the number that decides if the contactor handles your induction motor across the line. For resistive or lightly inductive loads, the AC-1 thermal current is higher, but the AC-3 figure is the one that matters for pump, fan, and compressor duty. The AC-4 rating of 29 A at 400 V covers plugging and inching applications where the contactor makes and breaks stalled rotor current. The coil pulls 24 VDC nominal; auxiliary contact ratings at DC-13 are 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V — useful for sizing the control transformer and verifying contact wear under DC switching. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Pollution degree 3 means it's rated for industrial environments with conductive pollution — no need for additional conformal coating in a typical panel. Front face carries IP20 protection; the terminals are IP00, so the contactor expects to live inside an enclosure that provides the environmental seal.
Mounting and wiring
Fastens with screw and snap-on onto 35 mm DIN rail per EN 50022. Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without spacing — useful for compact motor control centers. Main circuit terminals are screw-type, accepting solid wire 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), and up to 2x (0.75 to 4 mm²) maximum. Stranded wire range goes to 2x (0.75 to 25 mm²). The minimum permissible cross-section at 40 °C is 16 mm² for the main circuit.
Compliance documentation
RoHS compliance date is 05/01/2012, covering substance prohibitions. The part carries the SIRIUS brand and is designed to meet IEC/EN standards for power contactors.