What It Is and What It Does
The Siemens SIRIUS 3RT2025-2XF40-0LA2 is a power contactor in the S0 frame size, designed for switching motor and resistive loads in control panels. It is controlled by a 110 V DC coil and terminates via spring-type terminals on both main and auxiliary circuits. The contactor carries an auxiliary switch for status feedback or interlocking. The DC coil draws an inrush current peak of 15 A and has a pick-up factor of 0.7 (1.25 on full-scale), meaning it reliably pulls in at 77 V DC and drops out below about 33 V DC. The operating time on DC is 30 to 50 ms, with an arcing time of 10 ms.
Key Ratings and What They Mean for Fit
The contactor's DC switching capacity is rated at 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V. For a 230 V AC motor load it is rated at 3 hp. The AC-3 maximum switching rate is 1 000 operations per hour, dropping to 300 per hour for AC-4 (plugging/inching). Mechanical service life is rated at 10 million operations typical. Mounting is screw or snap-on onto 35 mm DIN rail per DIN EN 60715. The contactor accepts 2x (1 to 10 mm²) solid or stranded on the main contacts and 2x (0.5 to 2.5 mm²) on the auxiliary contacts. The S0 footprint is 45 mm wide, 102 mm high, and 107 mm deep.
Where It Goes in the Panel
The S0 size and 45 mm width fit standard DIN-rail enclosures; minimum clearances are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, giving flexibility in tight layouts. Operating temperature range is -40 to +70 °C; storage from -55 to +80 °C. The spring-type terminals reduce wiring time compared to screw clamps — no re-torquing needed after thermal cycling.