What it is and where it lands
The Siemens 3RT2035-1AN20 is a SIRIUS S2 power contactor — the core switching device in motor control centers and industrial panel builds. It mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715, so it drops into any standard European-profile panel without adapter plates. Envelope is 55 mm wide, 114 mm tall, 130 mm deep — fits the S2 frame footprint. Clearance distances are 10 mm upwards, forwards, and downwards, with 6 mm at the sides.
What the ratings mean for fit
Main contacts are 3-pole normally open (3 NO). The auxiliary switch is included on the unit — no separate add-on block needed for basic feedback. Switching frequency varies by duty class: 1200 cycles/hour at AC-1 (resistive), 1000 at AC-3 (standard motor start/run), 750 at AC-2 (slip-ring motor), and 300 at AC-4 (plugging/inching). The AC-3e rating also sits at 1000 cycles/hour. For a typical conveyor or pump cycling every 30 seconds, the AC-3 figure governs — stay under 1000 cycles/hour to avoid overheating the arc chamber. Auxiliary contact ratings are given at multiple voltages: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, 3 A at 400 V, 0.6 A at 440 V, and 40 A at 480 V. The 40 A at 480 V figure likely refers to a specific short-time or making current rating — verify the duty cycle against your PLC input or relay coil load. Motor horsepower rating is 7.5 hp at 230 V — a direct selection anchor for 230 V three-phase motor circuits in North American legacy panels.
Panel integration notes
Mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward/backward. Useful when the contactor sits on a swing-out subpanel or a non-standard orientation. Coil terminals are screw-type. Main and auxiliary terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded copper. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The storage figure matters for spares kept in unheated warehouses — the contactor can sit at -55 °C without damage, but don't energize the coil below -25 °C. Mechanical endurance is 10 million operating cycles typical — that's the contactor body itself, not the contacts under load. Contact life under AC-3 duty will be lower; plan inspection intervals around the switching frequency and load current. Arcing time is 10 to 20 ms; operating time (coil pick-up) is 10 to 18 ms at AC. These numbers matter for coordination with upstream short-circuit protection devices — the contactor must clear or withstand until the fuse or breaker opens.