The Siemens SIRIUS 3RT1035-3AL20-ZW97 is a size S2 power contactor rated for 18.5 kW at 400 V in AC-2 duty, and 22 kW at 500 V in AC-3 duty, with screw-type terminals on the main circuit.
The 18.5 kW AC-2 rating at 400 V means it handles slip-ring motor loads or other moderate inrush applications up to that power level — AC-2 covers starting and plugging duty, so it's not just a resistive load switch. The 22 kW AC-3 rating at 500 V covers standard squirrel-cage motors; that's the number to size against if your motor is a direct-on-line start. At 690 V it's rated 11.4 kW, so the same contactor works on 690 V systems with a derated motor load. Coil-side ratings: at 24 V it switches 10 A, at 230 V it switches 6 A, and at 400 V it switches 3 A — these are the auxiliary contact capacities, not the main pole current.
Deployment context
This contactor is DIN-rail mountable and side-by-side mountable, so it fits into standard control panels without extra spacing. The front is IP20 (finger-safe), the terminals are IP00 (touch-hazard at the connection point), so keep the panel door closed during operation.