What the ratings mean for fit
The 3RT1035-3BW40 is a Siemens SIRIUS power contactor in size S2, rated for 22 kW at 500 V AC-3 duty — that's the motor-switching rating that governs the real load, not the higher AC-1 resistive figure. AC-3 at 400 V is 18.5 kW, and AC-4 at 400 V is 35 A, so the contactor is sized for standard three-phase induction motors up to that power band. The mechanical life is 10,000,000 operations typical, which is the figure to use for maintenance interval planning. Mounting is screw and snap-on onto 35 mm standard mounting rail per DIN EN 50022. Side-by-side mounting is permitted, which matters when packing multiple contactors in a row — no derating gap required for that layout. The front face carries IP20, the terminals are IP00, so the panel enclosure provides the environmental seal.
Terminal and wiring detail
Main current circuit uses screw-type terminals. Solid conductors: 2x (0.25 to 2.5 mm²). Stranded: 2x (0.75 to 25 mm²). At 40 °C, the minimum permissible conductor cross-section is 16 mm² — that's the thermal derating floor, not the mechanical minimum. Pollution degree 3 means the contactor is rated for conductive pollution environments typical of industrial control panels.
Switching frequency and coil data
Maximum switching rates: AC-1 at 1200 operations per hour, AC-3 at 1000, AC-2 at 600, AC-4 at 300. The arcing time is 10 to 15 ms, and DC arcing is 20 to 25 ms — that's the interval the contacts sustain the arc before clearing, relevant for DC load derating. Coil rated value is 48 V; at 24 V the contactor switches 10 A, at 60 V it switches 2 A, at 110 V it switches 1 A, at 220 V it switches 0.3 A, at 230 V it switches 6 A, at 400 V it switches 3 A.