What it is and where it fits
The Siemens 3RT1034-3XF44-0LA2 is a SIRIUS power contactor in the Size S2 frame, designed for switching motor loads in industrial control panels. It carries a 110 VDC coil and terminates with screw-type terminals on the main current circuit. The contactor snaps onto a 35 mm DIN rail per DIN EN 50022 or can be screw-mounted, so it integrates directly into a standard panel layout.
Key ratings and what they mean for your panel
Rated for AC-3 duty at 400 V at 15 kW, this contactor handles typical three-phase induction motor loads up to that power — think pumps, fans, or small conveyors. The AC-1 maximum switching rate of 1 200 cycles per hour tells you it can keep up with frequent resistive load switching; AC-4 at 250 cycles per hour covers plugging or inching duty. Coil pickup at 70% of rated voltage (77 VDC) and dropout below that threshold means the control circuit needs a clean 110 VDC supply — verify your DC bus isn't sagging under load. Auxiliary contacts are rated at 24 VDC for 10 A, 110 VDC for 1 A, and 220 VDC for 0.3 A — these numbers govern what pilot devices or PLC inputs you can drive directly without an interposing relay. The arcing time of 10 to 15 ms and DC operating time of 20 to 30 ms are tight enough for most sequencing but worth noting if you're coordinating with fast solid-state outputs.
Mounting and wiring constraints
Clearance requirements: 10 mm upwards, downwards, forwards, and at the side. That's tight — you can pack these side-by-side (side-by-side mounting is supported) but keep the 10 mm breathing space for arc flash and heat dissipation. Solid and stranded wire ranges: main circuit accepts 2x (0.75 to 25 mm²) stranded or 2x (0.75 to 16 mm²) solid; control circuit takes 2x (0.25 to 2.5 mm²) solid. Strip length follows standard practice for screw terminals — aim for 8-10 mm stripped and torque to the manufacturer's spec.