The Siemens 3RT2037-3AG20 is a SIRIUS S2 power contactor from the current-production line. It carries a 65 A AC-3 rating at 480 V, which is the number that decides motor-load fit for a 480 V three-phase supply — that's the full-load current it can switch under motor starting duty, not the resistive AC-1 figure. The main contact configuration is 18...1 (three poles normally open, one auxiliary normally closed).
Mounting and integration
Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715. The S2 frame is 55 mm wide, 114 mm tall, 130 mm deep. Clearance requirements: 10 mm upwards, forwards, and downwards; 6 mm at the sides. Mounting position is flexible — the contactor can be rotated ±180° on a vertical surface and tilted forward or backward ±22.5° on a vertical surface. That covers most panel layouts without derating.
Terminals and switching frequency
Coil connection uses spring-type terminals — no screwdriver needed for the coil circuit, which speeds panel wiring. Main contact wire range: 2x (0.5...2.5 mm²) solid or stranded. Switching frequency varies by duty class: 800 operations/hour at AC-1 (resistive), 700 at AC-3 (motor start/run), 400 at AC-2 (slip-ring motor), and 200 at AC-4 (plugging/inching). The AC-3e maximum matches the AC-3 figure at 700 ops/hour.