What It Is and What It Does
The Siemens 3RT2025-1XF40-0LA2 is a SIRIUS power contactor in size S0, designed for switching motor loads and resistive loads in industrial control panels. It carries a 110 V DC coil with screw-type terminals, and mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The 110 V DC coil is the key fit parameter here — if your control voltage is 110 VDC, this is the variant you need. The DC coil holds in at 110 V nominal; inrush current peaks at 15 A.
Key Ratings and What They Mean for Fit
This contactor is rated for AC-3 switching duty at up to 1,000 operations per hour, which covers standard motor starting and running for pumps, fans, and conveyors. AC-4 duty (plugging/reversing) is limited to 300 operations per hour — the higher electrical wear from inrush under reverse torque means you need to derate the mechanical life. Operating temperature range of -40 to +70 °C means it can live in unheated enclosures or near hot machinery without derating. Storage range extends to -55 to +80 °C. Mounting position is flexible: +/-180° rotation on a vertical surface, and can be tilted forward/backward by +/- 22.5°. The required clearances are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the sides — tight enough for dense DIN-rail layouts. Screw terminals accept solid conductors: 2x (1 to 2.5 mm²) and 2x (2.5 to 10 mm²). Stranded connections are 2x (0.5 to 1.5 mm²) and 2x (0.75 to 2.5 mm²). Main contacts have a tightening torque range of 16 to 8 Nm.
Where It Goes in the Panel
Size S0 is the compact frame in the SIRIUS contactor family — 45 mm wide, 85 mm tall, 107 mm deep. It snaps onto a standard 35 mm DIN rail, so it integrates into any control panel using that rail profile. The auxiliary switch option (built-in) saves an extra module slot when you need feedback to the PLC.