What it is and what it does
The Siemens 3RT2028-1AS00 is a SIRIUS power contactor in the S0 frame size, designed for switching motor loads and resistive loads in industrial control panels. Its key rating is 34 A at 480 V under AC-3 duty (cites:), which is the standard category for starting and stopping squirrel-cage motors — so it handles motor loads up to that current without welding the main contacts during inrush. It mounts via screw fixing or snaps onto a 35 mm DIN rail per DIN EN 60715 (cites:), which is the standard panel integration method across most industrial enclosures. The S0 frame keeps the width to 45 mm (cites:), so it fits in a standard 45 mm slot on a DIN rail — no special adapter needed.
Key ratings and what they mean for fit
The 34 A at 480 V AC-3 rating (cites:) is the headline number for motor switching. AC-3 means it makes and breaks motor loads during starting and stopping — the contacts are designed to handle the high inrush current (typically 6–8x FLA) without excessive wear. For resistive loads (AC-1), the contactor can switch up to 1 000 operations per hour (cites:), while AC-3 duty is rated at 750 operations per hour (cites:). That operating frequency tells you it's suited for moderate-duty cycling — not a high-speed pick-and-place application, but fine for conveyors, pumps, and fans. The coil termination uses screw-type terminals (cites:), and the main contacts accept solid or stranded wire from 1 to 10 mm² (cites:,). Auxiliary contacts are included (cites:), which simplifies wiring for status feedback or interlocking without adding a separate auxiliary block. Rated operating temperature is -25 to +60 °C (cites:), with storage from -55 to +80 °C (cites:). That covers most indoor panel environments; if the panel is near a furnace or in direct sunlight, the 60 °C ceiling is the limit to watch.