The Siemens SIRIUS 3RT1035-1BB40-ZX95 is a Size S2 power contactor rated for 22 kW at 400 V in AC-3 duty — that's the motor-switching curve, so it handles three-phase induction motors up to that load without derating. Coil pulls 24 VDC; the contactor drops out between 20 and 25 ms on DC, arcing clears in 10 to 15 ms. Screw terminals on the main circuit accept up to 2x 16 mm² stranded or 2x 25 mm² stranded on the line side.
What the ratings mean for the panel
AC-3 at 400 V is the real-world motor rating: 22 kW covers a 30 hp class motor on a 400 V line. The AC-4 rating of 35 A at 400 V matters for reversing or inching duty where the contactor makes and breaks stalled-rotor current — that's a tougher thermal cycle. Maximum switching frequency at AC-3 is 1 000 operations per hour; at AC-4 it drops to 300 per hour because the arc energy is higher. The auxiliary contacts handle 10 A at 24 VDC, 6 A at 230 V, tapering to 0.3 A at 220 VDC — enough for a PLC input or a holding relay, but not a second contactor coil without a suppression network.
Mounting and integration
Snaps onto 35 mm DIN rail per EN 50022, or screws to a backplate. The S2 frame is 55 mm wide, 112 mm tall, 130 mm deep — fits a standard 200 mm deep enclosure with room for the gland plate. Side-by-side mounting is allowed, so you can gang contactors without a gap; just watch the heat buildup if you're running near the AC-4 limit. Pollution degree 3 means it's rated for conductive dust and condensation typical of industrial control panels — no extra conformal coating needed for most environments.