Reversing starter with AS-Interface bus
The Siemens 3RK4320-3KQ51-1BA2 is a SIRIUS reversing motor starter designed for AS-Interface bus communication. It integrates a bimetal motor protection relay with CLASS 10 trip characteristic, electromechanical switching contacts, and short-circuit protection via circuit-breakers — all in a single enclosure rated IP54.
Rated current and motor duty
Rated 5 A at 400 V in both AC-3 (motor starting) and AC-4 (reversing/inching) duty classes — the same current ceiling applies across both operating modes, so the reversing function doesn't force a derating step. The operating voltage range is 340 to 440 V at 50/60 Hz. The ambient temperature operating range is -25 to +50 °C.
DC control supply and AS-Interface integration
Control supply voltage is 20.4 to 26.4 V DC — the same rail that powers the AS-Interface bus. Two digital inputs are available for local switching commands. The unit supports AS-Interface protocol natively; PROFIBUS DP and PROFINET are not implemented on this variant.