What it is and where it lands
The Siemens 3RT2035-1AU04 is a SIRIUS power contactor in size S2, designed for switching motor loads in industrial control panels. It mounts via screw and snap-on onto 35 mm DIN rail per DIN EN 60715, so it integrates into standard enclosure layouts without custom bracketing. At 55 mm wide and 174 mm deep, it occupies a single DIN-rail module footprint — the width is the panel-space constraint, and the depth fits standard 200 mm+ enclosures without gland-plate interference.
Mounting and integration notes
Mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward/backward. That means you can orient the contactor to match existing busbar runs or cable entry without derating — useful when retrofitting into a crowded panel. Clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side. The 6 mm side gap is the tightest constraint — adjacent components on the same DIN rail need that air space for arc containment and heat dissipation. Main contact wiring accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded. The magnet coil uses screw-type terminals — no push-in or spring-cage on the coil circuit, so factor in screwdriver access for commissioning.
Lifecycle and sourcing posture
This part is sourced to order against an RFQ through standard industrial-automation distribution channels.
What the ratings mean for the buyer
The contactor is rated for AC-1 resistive loads at 1,200 operations per hour, AC-3 motor switching at 1,000 ops/h, and AC-4 plugging/reversing at 300 ops/h. The AC-3 rate governs most conveyor and pump duty; the AC-4 rate is the limiting factor for high-inertia or reversing applications — if your cycle rate exceeds 300 per hour under AC-4, this contactor will overheat. Arcing time is 10 to 20 ms, and the closing time (at AC) is 10 to 18 ms. These are fast enough for most motor starters but matter if you're coordinating with upstream short-circuit protection — the arcing time window affects let-through energy calculations. Mechanical life is typical at 10,000,000 operations. Auxiliary contacts are 18 NO to 1 NC.