What it is and where it fits
The Siemens SIRIUS 3RT2026-1AM20-1AA0 is a power contactor in the S0 frame size, 45 mm wide, designed for screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715. It carries an auxiliary switch and uses screw-type terminals for the magnet coil and main contacts.
Key ratings and what they mean for your panel
The S0 frame size and 45 mm width define the panel footprint — this contactor occupies one standard 45 mm slot on the DIN rail, with 10 mm clearance upwards, downwards, and forwards, and 6 mm at the sides. Mounting position is standing on a horizontal surface. Switching frequency varies by duty class: up to 1,000 operations per hour at AC-1 (resistive loads), 750/h at AC-2 and AC-3 (motor starting/running), and 250/h at AC-4 (plugging, inching). The AC-3e rating also caps at 750/h. These limits govern the contactor's thermal endurance — exceeding them in a high-cycle application (e.g., frequent reversing on a conveyor) will shorten service life. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. The wider storage range covers handling and shipping, not running — the -25 °C floor matters for unheated enclosures in cold climates. Main contacts accept solid or stranded wire from 1 to 10 mm², with dual-wire capability for smaller gauges (2x 0.5 to 1.5 mm² or 2x 0.75 to 2.5 mm²). The auxiliary switch is rated at 24 V for 10 A, derating to 0.3 A at 220 V and 3 A at 400 V — these are the switching limits for the built-in auxiliary, not the main contactor rating.