The Siemens SIRIUS 3RK1325-6KS71-1AA0 is a reversing motor starter — a single enclosure that handles forward/reverse control of a three-phase motor up to 0.75 kW at 400 V (0.7 hp at 460/480 V). It is designed as a reversing starter, meaning it integrates two contactor paths and mechanical interlocking for direction reversal without external wiring. The 24 V DC control supply (20.4...28.8 V range) powers the onboard logic and AS-Interface communication. IP65 protection means the enclosure withstands washdown environments — suitable for food-and-bev or outdoor conveyor lines where dust and hose-directed water are present.
The trip class selection (CLASS 5, 10, 15, 20) lets you match the overload relay's thermal curve to the motor's starting profile — CLASS 10 for standard-start pumps and fans, CLASS 20 for high-inertia loads like centrifuges or crushers that take longer to accelerate. The 0.75 kW at 400 V rating (0.7 hp at 460/480 V) sets the maximum motor size this starter can switch in AC-3 duty; a larger motor would overload the contactor's breaking capacity. Four digital inputs and one digital output are available for local sensors or status feedback, all wired through the M12 plug addressing port. The 25 ms ON-delay and 35 ms OFF-delay are fixed — no field adjustment — so sequence timing must accommodate these windows.
Mounting is via screw fixing, not DIN rail — plan for four drilled holes in the backplate. The enclosure measures 294 mm wide by 215 mm high by 159 mm deep; the width is the dimension that drives cabinet cutout spacing, especially when ganging multiple starters. Mounting position is flexible (vertical, horizontal, or flat), though horizontal is recommended for optimal heat dissipation. Shock resistance is rated at 12g for 11 ms, and vibration resistance at 7 mm / 2g — this starter survives on mobile equipment or near heavy machinery without nuisance trips.
Communication and connectivity
The starter communicates via AS-Interface (Actuator-Sensor Interface) — a fieldbus common in material handling and packaging lines for connecting binary sensors and actuators. It does not support PROFIBUS DP or PROFINET, so if your control network is Siemens S7 with PROFINET, you will need a gateway or a different starter variant. Device addressing is done through an M12 plug, which is standard for AS-i nodes. The main circuit connects via a HAN Q4/2 plug conforming to ISO 23570 — a heavy-duty industrial connector rated for the motor current. No direct start capability; the reversing starter always requires a forward/reverse command from the AS-i master.