What it is and where it lands
The Siemens 3RT2025-2EL20 is a SIRIUS power contactor in Size S0, built for switching motor loads and resistive loads in industrial control panels. It mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 60715, and the mounting position allows +/-180° rotation on a vertical surface plus +/-22.5° tilt forward and backward — useful when you're fitting into a tight enclosure layout.
Key ratings and what they mean for fit
The main contacts are rated 18 A for AC-3 duty (motor switching) at 400 V, and 8 A for AC-1 (resistive load) at the same voltage. That 18 A AC-3 rating means it handles a 7.5 kW motor at 400 V three-phase — the typical sizing for a small conveyor or pump. The auxiliary switch is rated 10 A at 24 V, 2 A at 48/60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 0.6 A at 440 V — these are the contact ratings for the built-in auxiliary block, so you can use it for PLC feedback or status indication without adding a separate aux contactor. Switching frequency maxes out at 1,000 operating cycles per hour for AC-1, AC-2, AC-3, and AC-3e duty, dropping to 300 cycles per hour for AC-4 (plugging/inching). The mechanical life is rated at 10 million operations typical — that's a long service interval for a panel that cycles a few times per minute. Spring-type terminals on the magnet coil and main/auxiliary contacts accept solid or stranded wire from 1 to 10 mm², with dual-wire capacity for 2x (0.5 to 2.5 mm²). The 45 mm width and 97 mm depth fit the standard S0 footprint — same as the 3RT2015 and 3RT2016 siblings, so it drops into the same DIN rail slot without re-drilling the panel.
Environmental and mounting notes
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. The contactor can be mounted in any orientation within the stated rotation limits, and the clearance requirements are 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side — keep those clearances for heat dissipation and arc quenching.