SIRIUS S2 power contactor for motor and resistive loads
The Siemens 3RT2036-1AQ20 is a SIRIUS Size S2 power contactor rated for 52 A at 480 V in AC-3 duty — the motor-switching rating that governs real-world induction motor loads up to that current. It carries an auxiliary switch block factory-installed, so you get one less add-on to spec and wire into the control circuit. Mounting is screw-fixed or snap-on onto 35 mm DIN rail per DIN EN 60715, with generous position flexibility: ±180° rotation on a vertical surface and ±22.5° tilt forward or backward. That means it fits into tight retrofit panels where the rail is already populated and you cannot reorient the whole assembly. Dimensions are 130 mm deep, 114 mm tall, and 55 mm wide — the S2 footprint that matches the SIRIUS 3RT2 family. The 55 mm width is three standard 18 mm module slots, so it occupies predictable DIN space in a multi-contactor lineup.
Ratings that decide the fit
The headline AC-3 rating of 52 A at 480 V is the number that determines whether this contactor handles a given three-phase motor. AC-3 covers starting and plugging of squirrel-cage motors — the most common duty in conveyor, pump, and fan panels. For resistive loads (AC-1), the maximum operating rate is 1 000 switching cycles per hour; for AC-3 it is 800 cycles per hour, and for the heavier AC-4 duty (inching, plugging) it drops to 250 cycles per hour. These rates tell you the thermal recovery time between operations — useful when sizing for a frequent-start application like a crane or a press. The auxiliary contact ratings cover control-voltage switching: 10 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V. If your PLC output drives the contactor coil through an interposing relay, these numbers confirm the auxiliary contacts can handle the pilot-duty load without welding. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. The 60 °C ceiling is typical for a contactor in a ventilated enclosure; if your panel sits near a furnace or in a Middle East summer, derate the continuous current above 40 °C per the manufacturer's thermal curve.
Integration and wiring
Main contact wiring accepts two conductors per terminal: 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 spring-cage on the coil side, so factor in screwdriver access during panel build. Clearance spacing: 10 mm upwards, forwards, and downwards; 6 mm at the sides. That is the minimum air gap to adjacent metalwork or another contactor. Mechanical life is rated at 10 000 000 operating cycles typical — well beyond the electrical life for most AC-3 applications, meaning the contactor will wear out electrically before it wears out mechanically. Arc duration is 10 to 20 ms, and closing time (AC coil) is 10 to 18 ms.