It's a fully integrated motor control and protection unit — not just a contactor, but a combination of a contactor, overload relay, and AS-Interface communication interface in one housing. The operating voltage range is 340 to 440 V, covering common 400 V three-phase industrial supplies. This unit integrates two digital inputs and a motor brake output (24 V DC control supply, 20.4 to 26.4 V range), so it can handle local pushbuttons and a holding brake directly without an external interface module. The bimetal overload protection is electromechanical — a proven, field-reliable technology that doesn't depend on electronics for the thermal curve. Short-circuit protection is handled by circuit-breakers upstream, which the starter is coordinated with.
Deployment context: panel integration and environment
The 3RK4320-3FQ54-0BA3 is rated IP54, so it's suitable for installation in control cabinets where dust and splash ingress are a concern, but not for direct washdown zones. Dimensions are 245 mm wide by 215 mm high by 205 mm deep — a substantial footprint, so check your DIN-rail or backplate layout before committing. The unit communicates exclusively via AS-Interface — it does not support PROFIBUS DP or PROFINET, so the network architecture must be AS-i at the field level, with a gateway to higher-level fieldbuses if needed.
If you need a cross-reference, the SIRIUS family includes other motor starters with different communication protocols or current ratings, but the AS-Interface variant is specific to this order code.