Integrator's first look
The Siemens SIRIUS 3RT1034-1AP04-1AA0 is a Size S2 power contactor with screw-type terminals on the main current circuit. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022, so it fits standard panel layouts without adapter plates. The front face carries IP20; the terminal area is IP00, meaning the wiring compartment needs enclosure-level protection in dirty environments. Rated for AC-2 duty at 400 V delivering 15 kW, and AC-4 at 400 V at 29 A — these are the numbers that govern motor switching for slip-ring or reversing applications. At 500 V it handles 18.5 kW; at 690 V it drops to 10 kW, so the voltage derating is steep above 500 V.
Wiring and termination
Terminals accept solid conductors: 2x (0.5 … 1.5 mm²), 2x (0.75 … 2.5 mm²), max. 2x (0.75 … 4 mm²). Stranded goes up to 2x (0.75 … 25 mm²). At 40 °C the minimum permissible cross-section is 16 mm², so for full-rated current you need at least that gauge on the power path. The contactor occupies 55 mm width, 112 mm height, 164 mm depth — verify clearance for the screw-terminal wiring arc and the 10–15 ms arcing time when spacing from grounded metal.
Environmental and lifecycle
Mechanical endurance is typical 10,000,000 operations. Maximum switching frequency varies by duty: AC-1 at 1,200 cycles/h, AC-2 at 750, AC-3 at 1,000, AC-4 at 250. For high-cycle reversing or jogging applications, the AC-4 limit is the binding constraint.