What it is and what it does
The Siemens 3RT2025-2AP04 is a SIRIUS power contactor in the compact S0 frame size, designed for switching motor loads in control panels. It mounts via screw or snap-on onto 35 mm DIN rail per EN 60715, fitting into a 45 mm wide slot — standard for a three-pole contactor at this rating class. Rated 14 A at 480 V in AC-3 duty (motor starting and running), it handles typical 3 hp loads at 230 V and 3 A at 400 V. The AC-1 resistive rating supports 1 000 switching cycles per hour, while AC-4 (inching/plugging) is limited to 300 cycles per hour — a real constraint if the application requires frequent reversing. The coil uses spring-type terminals (no screw clamp on the magnet coil), accepting solid or stranded wire from 1 to 10 mm². Main contact terminals accept 18 to 8 AWG or 2x (0.5 to 2.5 mm²) — enough for the rated current but worth noting if you're paralleling conductors.
Mounting and integration
The contactor occupies 45 x 102 x 144 mm (W x H x D). Clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the sides. On a vertical mounting surface, the unit can be rotated ±180° and tilted forward/backward ±22.5° — useful when fitting into tight or non-standard panel layouts. Operating temperature range is -25 to +60 °C; storage from -55 to +80 °C. No built-in auxiliary switch is included on this variant — if you need feedback contacts, plan for a separate auxiliary contact block or a different order code.