What it is and what it does
The Siemens 3RT2028-1AG20 is a SIRIUS power contactor, Size S0, designed to switch motor loads and resistive heater banks in industrial control panels. The 24 VDC coil pulls in reliably across the operating range, and the screw-type terminals on the magnet coil accept solid or stranded copper up to 10 mm² — no special crimp tools needed for a field swap.
Mounting and integration
Snaps onto 35 mm DIN rail per DIN EN 60715, or screws directly to a backplate. At 45 mm wide, it leaves room for an auxiliary contact block alongside without crowding the next device. Mounting position is flexible — ±180° rotation on a vertical surface, plus ±22.5° tilt forward or backward — handy when you're squeezing into an existing enclosure layout.
Environmental limits
Rated for operation from -25 °C to +60 °C, which covers most indoor panel environments and even unheated plant floors. Storage range stretches from -55 °C to +80 °C — fine for a spare sitting on a shelf in a non-climate-controlled warehouse.