The Siemens 3RK4320-5DQ61-0BA3 is a SIRIUS MCU motor starter designed for AS-Interface bus communication, meaning it integrates motor starting, solid-state overload protection, and network control into a single enclosure for distributed automation layouts. Rated 1.25 A at AC-3 duty at 400 V, this direct starter handles small induction motors (roughly 0.37 kW at 400 V three-phase) and carries a CLASS 10 trip curve, so it clears a stalled rotor fast enough for most conveyor and pump applications without nuisance tripping on normal start-up. The solid-state switching contact and solid-state motor protection mean there are no mechanical contacts to weld or arc, which suits frequent cycling — the rated operating frequency is up to 3,600 operations per hour.
Bus integration and I/O
This unit speaks AS-Interface natively (AS-i protocol supported), with two digital inputs onboard for local sensors or pushbuttons, and a brake control output rated for 400 V AC. The control supply voltage is 20.4 to 26.4 V DC, which is the standard AS-i power rail, so it drops into an existing AS-i network without a separate control transformer. No PROFIBUS DP or PROFINET protocol onboard — communication is AS-Interface only, so plan the network gateway accordingly.
The enclosure measures 290 mm wide × 215 mm high × 205 mm deep and carries an IP54 protection class, so it's suited for control cabinets in dusty or damp industrial environments but not for direct washdown zones.