The Siemens SIRIUS 3RT1035-1AP64 is a size S2 power contactor rated for 22 kW at 400 V in AC-3 duty and 18.5 kW at 400 V in AC-2 duty, making it a fit for motor switching in pump, fan, and conveyor applications where the load is predominantly inductive. The 55 mm wide frame snaps onto a 35 mm DIN rail per EN 50022, and the front face carries an IP20 rating while the terminal area is IP00 — standard for panel-mounted contactors where the enclosure provides the environmental seal.
AC-3 rating at 22 kW / 400 V is the headline number — this contactor switches squirrel-cage motors up to that load without welding the main contacts during inrush. The AC-2 rating of 18.5 kW at 400 V covers slip-ring motor starting, where the current stays closer to full-load during acceleration. For resistive loads (AC-1), the maximum operating rate is 1 200 cycles per hour; for AC-3 it drops to 1 000 cycles per hour, and for the punishing AC-4 plugging/reversing duty it is 300 cycles per hour — the thermal capacity of the S2 frame limits how fast you can slam it in and out under load. The auxiliary contact ratings cover a 24 V DC control circuit at 10 A, stepping down to 0.3 A at 220 V DC — useful for interlocking with a PLC output or a safety relay. The coil operates between 0.8 and 1.1 times the rated voltage at both 50 Hz and 60 Hz, so a 208-240 V control transformer is fine; the 7 to 20 ms closing time and 10 to 15 ms arcing time are typical for this frame size. The screw-type main circuit terminals accept stranded wire up to 2x 25 mm², and the solid/stranded auxiliary terminals handle 2x 0.5 to 4 mm².