Siemens SIRIUS 3RT1034-1XB40-1LA4 — S2 Power Contactor, AC-4 Rated 29 A
The Siemens SIRIUS 3RT1034-1XB40-1LA4 is a size S2 power contactor designed for switching motor loads in industrial control panels. Its 29 A rating in AC-4 duty at 400 V means it handles the severe inrush and plugging/ reversing cycles typical of crane, hoist, and press drives — not just steady-state running. The 18.5 kW rating at 500 V and 10 kW at 690 V cover the motor power range for a 400 V class machine.
Mounting and Wiring
Mounts via screw and snap-on onto 35 mm standard rail per DIN EN 50022, and side-by-side mounting is permitted — no derating gap required between contactors in a multi-contactor panel. The main current circuit uses screw-type terminals; solid wire capacity is 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²), max 2x (0.75 to 4 mm²). Stranded wire accepts 2x (0.75 to 25 mm²). The front face carries IP20 protection; the terminal area is IP00, so finger-safe shrouding on the terminals is the panel builder's responsibility.
Duty Cycles and Life
Maximum mechanical life is 10 million operations typical. Switching frequency varies by duty: 1 200 cycles/hour in AC-1 (resistive), 1 000 in AC-3 (motor running), 750 in AC-2 (slip-ring motor), and 250 in AC-4 (plugging/reversing). The 29 A AC-4 rating is the one that governs for severe-duty applications — that figure, not the AC-3 number, decides whether this contactor survives a reversing conveyor or a hoist with frequent inrush cycles.