What it is and what it does
The Siemens 3RT2026-1AM20 is a SIRIUS S0 power contactor — the core switching element in a motor starter or load-management circuit. Screw-type terminals on the coil and main contacts, with an integrated auxiliary switch. It mounts on 35 mm DIN rail per EN 60715, either snapped on or screwed down. Rated for 750 switching cycles per hour at AC-3 duty (motor starting) and the same at AC-2. At AC-1 (resistive loads) it handles 1,000 ops/h; at AC-4 (plugging/inching) the rate drops to 250 ops/h. The mechanical service life is rated at 10 million operations typical. The auxiliary contact block carries 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 3 A at 400 V. At 230 V it is rated for 3 hp motor load.
Panel fit and wiring
Dimensions: 85 mm high, 45 mm wide, 97 mm deep. The S0 frame size is the standard footprint for contactors in this current class — it occupies one DIN-rail module width (45 mm). Wire termination: solid or stranded conductors from 1 to 10 mm². Two conductors can share a terminal: 2x 0.5–1.5 mm² or 2x 0.75–2.5 mm². Main contacts accept 16 to 8 AWG. Mounting position is flexible — the contactor can be rotated ±180° on a vertical surface and tilted forward/backward ±22.5°. Clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, 6 mm at the side.
Environmental and lifecycle
Coil sealing current: 0.25 A at 50 Hz, 0.28 A at 60 Hz. Operating time at AC: 4 to 16 ms. Arcing time: 10 ms.