Siemens 3RT2028-1AU20 SIRIUS Power Contactor — S0 Frame, DIN Rail Mount
The Siemens 3RT2028-1AU20 is a SIRIUS power contactor in the S0 frame size, designed for screw and snap-on mounting onto 35 mm DIN rail per DIN EN 60715. The contactor occupies a 45 mm width on the DIN rail, with a depth of 97 mm and height of 85 mm — standard S0 footprint that fits existing panel layouts without re-drilling gland plates. An auxiliary switch is included on the contactor, saving a separate add-on block for basic status feedback to the PLC or indication circuit.
Mounting and Clearance
Mounts on vertical surfaces with ±180° rotation possible; can be tilted forward/backward by ±22.5° on a vertical mounting surface, giving flexibility in tight enclosures. Minimum clearance to adjacent components: 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side — important for heat dissipation and arc-flash containment in a crowded panel.
Wiring and Terminals
Main contact terminals accept solid or stranded conductors from 1 to 10 mm², with screw-type terminals on the magnet coil. Auxiliary contact terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded wire — sufficient for control-circuit runs in a standard panel.
Switching and Operating Cycles
Rated for 1,000 operating cycles per hour at AC-1 (resistive load), 750 cycles/h at AC-2 and AC-3 (motor starting/running), and 250 cycles/h at AC-4 (plugging/inching) — the AC-4 figure governs frequent reversing or jogging applications. Arcing time is 10 to 10 ms per operation, with an AC switching time of 4 to 16 ms.
Environmental and Lifecycle
Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. Typical mechanical life is 10,000,000 operations.