What the ratings mean for your panel
The Siemens 3RT1035-1BB40 is a SIRIUS power contactor in the S2 frame size, built for switching motor loads in industrial control panels. Its 24 VDC coil holds at 10 A and drops out below 18 V — standard for PLC-driven 24 V control buses. The AC-3 rating of 22 kW at 500 V tells you it handles standard three-phase induction motors up to that power; at 690 V the same contactor is rated 11.4 kW, so the voltage derating is already baked in. The AC-4 rating of 35 A at 400 V covers reversing or plugging duty where the contactor makes and breaks stalled-rotor current — that's the number to check if your application does frequent inching or jogging. Mechanical life is rated at 10 million operations typical. At AC-3 the switching rate is 1,000 operations per hour; at AC-4 it is 300 per hour.
DIN rail fit and wiring
Mounts via screw and snap-on onto 35 mm DIN rail per EN 50022. Side-by-side mounting is supported, so you can gang multiple contactors without derating the thermal capacity — useful for compact motor control centers. The S2 frame footprint is 55 mm wide, 112 mm high, and 130 mm deep. Screw-type terminals for the main circuit accept stranded up to 2x 25 mm² and solid up to 2x 4 mm². The terminal enclosure is rated IP00, meaning the connection points are not sealed — the front face carries IP20 for finger-safe touch protection once wired. Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation — standard for unsealed panel gear. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The minimum wire size at 40 °C is 16 mm² — that's the smallest conductor that carries the full rated current without exceeding the terminal temperature rise.