What It Is and Where It Fits
The Siemens 3RT2038-1AC20 is a SIRIUS power contactor in size S2, designed for switching motor loads and resistive loads in control panels. It mounts on 35 mm DIN rail per DIN EN 60715 via screw or snap-on, with a footprint of 55 mm wide by 114 mm tall by 130 mm deep — fits into a standard panel cutout without modification. The coil is rated for 24 V at 50 Hz, and the switching contact arrangement is a 3-pole main contact configuration (18...1 — typically NO/NC coding). Mechanical life clocks in at 10 million operations, so it holds up in high-cycling applications like conveyor zones or packaging lines.
What the Cycling Ratings Mean
Maximum operating frequency varies by duty: AC-1 (resistive) allows up to 700 operations per hour, AC-3 (standard motor start) 500 1/h, and AC-4 (plugging/inching) 150 1/h. That directly governs the thermal rise and contact wear — a conveyor zone doing frequent start-stop under load is an AC-3 scenario, so the 500 1/h ceiling is the real limit; don't size by the AC-1 number.