What it is and what it does
The Siemens 3RK1322-1DS02-0AA4 is an AS-interface compact direct starter — an electromechanical DOL (direct-on-line) motor starter packed into an IP65 enclosure for mounting right out on the machine frame, not buried in a control cabinet. It's rated for 1.1 kW at 400 V AC-3 duty, so it handles a standard three-phase induction motor of that size. The bimetal overload relay sets between 2.2 A and 3.2 A, and the built-in short-circuit protection uses circuit-breakers, not fuses, which means a faster reset on a fault. The IP65 rating means the whole unit — body and optics — stands up to washdown and dust. Out here in the grease, that's the difference between a starter that survives a hose-down and one that's full of coolant next shift. Operating temperature from -25 °C to +55 °C covers most plant-floor conditions short of a foundry.
Bus communication and brake output
This starter talks over AS-interface (AS-i) — the two-wire bus that carries both power and data to field devices. It has bus communication onboard, with two integrated inputs for limit switches or sensors. No PROFIBUS DP on this variant, so if your line uses PROFIBUS, you'll need a gateway or a different module. A motor brake output is included, rated for 500 V DC / 1 A. That's useful for holding brakes on vertical-axis conveyors or palletizers — the kind of load that drops if the brake doesn't set when the motor cuts. The brake contact is separate from the main power contacts, so you can interlock it in the safety circuit.
Breaking capacity and fault current
The maximum short-circuit breaking capacity (Icu) at 400 V is 50,000 A. That's high for a compact starter — it means this unit can interrupt a severe fault without the upstream breaker having to clear it. In a panel with a 50 kA SCCR rating, this starter coordinates cleanly; you don't need a current-limiting fuse ahead of it.