What it is and where it goes
The Siemens 3RK1322-0HS02-1AA1 is an AS-Interface compact reversing starter — a self-contained motor control unit that handles forward/reverse switching, overload protection, and bus communication in one IP65 enclosure. It's designed for distributed motor control right at the machine, not back in a central panel. Rated for 0.21 kW at AC-3 duty on a 400 V line, it switches small three-phase motors — think conveyor drives, agitators, or valve actuators — up to that load. The setting range of 0.55 to 0.8 A means you dial the overload relay to match the motor's full-load current within that window. IP65 rating means the housing and all connections are sealed against hose-directed water and dust ingress. This unit mounts directly on the machine frame or a mounting plate near the motor — no separate enclosure needed.
Key ratings and what they mean for fit
The 50 kA short-circuit breaking capacity at 400 V (Icu) tells you this starter can safely interrupt a fault current up to that level without welding its contacts or rupturing the housing. That's a high fault-current rating for a compact unit — it lets you place it on a supply with substantial transformer capacity without needing upstream current-limiting fuses. Motor protection uses a bimetal overload relay — a thermal element that tracks motor heating. It's the traditional, field-proven approach; no electronics to fail in high-vibration or hot environments. The 0.55 to 0.8 A adjustment range covers small motors in the 0.21 kW class. The built-in motor brake output (24 V DC / 3 A) supplies power to release a spring-applied brake on the motor shaft. That's critical for vertical loads or any axis that must hold position when power is removed — the brake engages on power loss, preventing drift. Communication is over AS-Interface (AS-i), not PROFIBUS DP. Two integrated inputs let you wire limit switches or pushbuttons directly into the starter, reducing field wiring back to a central I/O rack.
Physical integration
Dimensions are 120 mm wide, 270 mm high, 190 mm deep. It's not a DIN-rail mount — the IP65 enclosure bolts directly to a machine frame or sub-plate via its mounting feet. The 9-pole tab terminals for the main circuit accept standard quick-connect receptacles; no screw terminals on the power side. Ambient temperature range of -25 to +55 °C covers most indoor industrial environments, including unheated warehouses. The IP65 seal holds up to washdown cycles, so it's suitable for food, beverage, or pharmaceutical lines where hosing down the machine is routine.