Motor Duty and Sizing
The Siemens SIRIUS 3RT1034-1AD00 is a size S2 power contactor rated for 18.5 kW at 500 V AC-3 and 10 kW at 690 V AC-3, covering the common motor voltage ranges for 4-pole induction motors up to about 25 hp at 480 V. The AC-4 rating of 29 A at 400 V matters for reversing or inching duty where the contactor breaks stalled rotor current — that's the figure to check for jogging applications, not the AC-3 number.
Coil and Auxiliary Ratings
The auxiliary contact ratings (10 A at 24 V, 6 A at 230 V, 3 A at 400 V) are enough to drive a PLC input or a smaller contactor coil downstream. Verify the free-wheel diode polarity on the coil suppression if you're paralleling aux contacts with an inductive load.
Side-by-side mounting allowed — no derating gap needed for the S2 frame. The main circuit screw terminals accept up to 2x 25 mm² stranded or 2x 16 mm² solid; the aux terminals handle up to 2x 4 mm² solid. That's enough for the motor leads on a 25 hp run.