What it is and what it does
The Siemens 3RT2037-1AF00 is a SIRIUS power contactor in size S2, designed for switching motor loads and resistive loads in industrial control panels. It carries a 65 A rating at 480 V, which is the AC-3 motor-switching current — the rating that governs real motor duty, not just resistive heating. It mounts on a 35 mm DIN rail per DIN EN 60715, using either screw or snap-on fastening, and occupies 55 mm width on the rail. The depth is 130 mm, so plan for that behind the gland plate. Operating temperature range is -25 to +60 °C, and storage range is -55 to +80 °C — the storage limit is for handling, not running.
Key ratings and what they mean for fit
The 65 A at 480 V is the AC-3 rating for switching three-phase motors. That is the number that decides whether this contactor handles your motor load. The 24 V coil draws 10 A at rated value — that is the inrush, not hold, so size your control transformer for that peak. Mechanical life is typical 10,000,000 operations. Electrical life varies by duty: AC-1 (resistive) max 800 operations/hour, AC-3 (motor start/run) max 700/hour, AC-4 (plugging/inching) max 200/hour. The AC-4 limit is the one that bites if you are reversing frequently. The auxiliary switch is included — screw-type terminals for the magnet coil. Main contact wiring accepts 2x 0.5 to 2.5 mm² solid or stranded.