What this contactor is and what it does
The Siemens 3RT1035-1BG40 is a SIRIUS-brand power contactor in the S2 frame size, designed for switching three-phase motor loads in industrial control panels. Its headline motor rating is 22 kW at 500 V under AC-3 duty — that's the standard category for starting and stopping squirrel-cage motors under load, so it handles the inrush and running current of a motor up to that power at that voltage. For heavy-duty jogging or inching applications where the contactor makes and breaks stalled-rotor current, the AC-4 rating at 400 V is 35 A — a useful figure for applications like crane drives or press controls that cycle under full load. The contactor mounts via screw and snap-on onto 35 mm standard mounting rail per DIN EN 50022, so it integrates directly into a standard DIN-rail panel layout without adapter plates.
Terminal and wiring detail
Main current circuit terminals are screw-type, accepting solid conductors from 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², and up to 2x 0.75 to 4 mm². Stranded conductors on the main circuit can go up to 2x 0.75 to 25 mm². The control circuit terminals accept 2x 0.5 to 1.5 mm² solid or 2x 0.75 to 2.5 mm² stranded. This gives good flexibility for panel wiring — you can land a 4 mm² feed on the main terminals and still fit a 1.5 mm² control wire in the same terminal without adapters. The front of the contactor carries an IP20 rating — finger-safe for panel installation. The terminal area itself is IP00, which is standard for enclosed contactors inside a cabinet. Storage temperature range is -55 to +80 °C, operating range is -25 to +60 °C, so it handles typical plant-floor conditions without derating concerns.
Switching performance and auxiliary ratings
Mechanical life is rated at 10 million operating cycles typical. Maximum switching frequency: 1,200 cycles/hour at AC-1, 1,000 at AC-3. For auxiliary switching or control-circuit applications, the contactor carries rated values at various voltages: 10 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V, 6 A at 230 V, and 3 A at 400 V. These are useful for pilot-duty or signal switching within the same contactor block.