The Siemens 3RT1034-3BB44-3MA0 is a SIRIUS-brand power contactor in the S2 frame size, rated for motor switching and resistive loads. The 24 VDC coil draws 10 A at inrush and 0.8 A holding — the holding current is the steady-state draw the PLC output or relay must sink. It snaps onto a 35 mm DIN rail per DIN EN 50022 or screws directly to a backplate. At 55 mm wide and 112 mm tall, it fits standard panel layouts without crowding adjacent devices. Screw terminals on the main circuit accept 2x (0.75...16 mm²) stranded or 2x (0.25...2.5 mm²) solid — enough for the full rated current without lug adapters. Pollution degree 3 means it tolerates conductive dust and occasional condensation; suitable for unsealed industrial enclosures.
Side-by-side mounting is permitted, so you can gang multiple contactors on the same rail without a mandatory gap — useful when packing a motor control center. The IP20 front cover protects against finger contact; the terminal area is IP00, so the panel door must guard live parts. Operating ambient is -25 to +60 °C; storage range -55 to +80 °C. The arcing time sits at 10 to 15 ms, and the DC operate / release times are 20 to 30 ms — fast enough for most sequencing but not for high-speed jogging.
Rated for AC-2 duty at 400 V at 15 kW — that covers slip-ring motor starting where the contactor opens under load. AC-4 rating at 400 V is 29 A, which handles plugging and inching of squirrel-cage motors. At 500 V it is rated 18.5 kW; at 690 V it derates to 10 kW. Maximum operating frequency varies by duty: 1 200 cycles/hour at AC-1 (resistive), 1 000 at AC-3, 750 at AC-2, 250 at AC-4. For a conveyor running at 30 starts/hour, any of these is fine; for a press that cycles 600 times/hour, AC-3 is the limit.
RoHS compliance date is 05/01/2012, meaning it meets the EU RoHS directive for substances of concern. The contactor carries a typical mechanical life of 10 million operations — the figure for the contactor body itself, not the contacts under load.