What it is and what it does
The Siemens 3RT1034-1AG20-1AA0 is a SIRIUS power contactor in frame size S2, designed for switching motor loads in industrial control panels. It's rated for 18.5 kW at 500 V under AC-3 duty (standard motor starting), and 15 kW at 400 V under AC-2 duty (slip-ring motor reversing or inching). The 690 V rating of 10 kW tells you it can handle higher-voltage motors, but at reduced power — the contactor's thermal capacity is the limit, not the coil. The screw-type terminals on the main circuit accept solid conductors up to 2x 4 mm² and stranded up to 2x 25 mm², which covers most motor leads up to the 18.5 kW range. The front face carries IP20 protection — safe for finger contact in an enclosed panel — while the terminal area is IP00, meaning live parts are exposed if the panel door is open.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per EN 50022. The 55 mm width and 112 mm height fit standard S2 contactor spacing. Side-by-side mounting is allowed. Depth is 115 mm. Operating temperature range is -25 to +60 °C, storage from -55 to +80 °C. Pollution degree 3 means it's rated for conductive pollution environments typical of industrial floors — no special conformal coating needed for most factory air.
Switching performance and life
Mechanical life is typical 10 million operations. Electrical life depends on duty: AC-1 allows up to 1,200 operations per hour, AC-3 up to 1,000 per hour, AC-4 drops to 250 per hour. Coil operates on 50/60 Hz, with a pickup range of 0.8 to 1.1 times rated voltage at 50 Hz, 0.85 to 1.1 at 60 Hz. Auxiliary contact ratings cover 24 V at 10 A down to 220 V at 0.3 A — enough for PLC inputs or relay coils in the control circuit.