What it is and where it lands
The Siemens 3RT1035-1BP40 is a SIRIUS power contactor, size S2, built for switching motor loads in control panels. It carries screw-type terminals on the main circuit and mounts via screw or snap-on onto 35 mm DIN rail per EN 50022 — no shop, no crane, just a rail clip and a screwdriver. At 55 mm wide it fits a standard panel slot; the IP20 front and IP00 terminal block mean it's fine inside an enclosure but needs finger protection at the wiring side.
What the ratings mean for fit
The 22 kW at 500 V and 11.4 kW at 690 V AC-3 ratings tell you this contactor handles standard three-phase squirrel-cage motors up to those power levels. The 18.5 kW at 400 V AC-2 rating covers slip-ring motors or wound-rotor applications where starting current stays high longer. At AC-4 at 400 V it's rated 35 A — that's inching, plugging, or reversing duty where the contactor makes and breaks stalled-rotor current. The 1 200 cycles per hour at AC-1 resistive load and 1 000 at AC-3 give you the thermal cycling headroom for frequent starts on conveyor or pump duty.
Termination and wiring
The main circuit accepts solid conductors up to 2x (0.5... 1.5 mm²) or 2x (0.75... 2.5 mm²), max 2x (0.75... 4 mm²). Stranded goes to 2x (0.75... 25 mm²). At 40 °C the minimum permissible cross-section is 16 mm² — that's the thermal limit for continuous current. The coil pick-up and drop-out times are 20 to 25 ms DC, arcing time 10 to 15 ms, which is standard for this size. Side-by-side mounting is allowed, so you can gang them on the rail without derating if the ambient stays within limits.