SIRIUS direct starter with AS-Interface — what it is and where it fits
The 3RK1315-6LS41-2AA5 is a Siemens SIRIUS direct starter — a self-contained motor start-and-protect unit that combines a contactor, overload relay, and AS-Interface communication in one IP65 enclosure. It is designed for distributed motor control where the starter sits near the motor rather than in a central panel, saving cabinet space and reducing point-to-point wiring. Rated 5.5 kW at 400 V (7.5 hp at 460/480 V, 10 hp at 575/600 V), it covers the common small-motor range for pumps, fans, conveyors, and small compressors in industrial and infrastructure installations.
Supply voltage, motor power, and trip coordination
The control supply is 24 VDC nominal, with a permissible range of 20.4 to 28.8 V DC — the 26.5 V minimum permissible and 31.6 V maximum permissible define the absolute limits for the internal electronics. A 24 VDC supply with ±15 % regulation keeps the unit inside its operating window. Motor power ratings are given per voltage region: 5.5 kW at 400 V, 5 500 W at 500 V (same value, different notation), 3 hp at 220/230 V, 7.5 hp at 460/480 V, and 10 hp at 575/600 V. The Trip Class is CLASS 10, meaning the overload relay trips within 10 seconds at 7.2× the set current — standard for general-purpose motor protection where the starting time is short. ON-delay time is 85 ms, OFF-delay time is 65 ms — these are the internal response times from the AS-Interface command to the power contacts changing state. For sequencing multiple starters, account for these delays in the PLC logic if coordinated start/stop timing matters.
Mounting, enclosure, and environmental fit
The unit measures 159 mm deep, 294 mm wide, and 215 mm high, with screw fixing as the fastening method. Mounting can be vertical, horizontal, or flat — the recommended orientation is horizontal, which aligns with the natural convection path for the overload relay's thermal memory. IP65 protection means the enclosure is dust-tight and protected against low-pressure water jets — suitable for washdown areas, outdoor cabinets, and locations where the starter is mounted directly on the machine frame rather than in a sealed panel. Pollution degree 3 confirms it is rated for conductive pollution typical of industrial floors. Operating temperature range is -25 to +55 °C, with storage and transport limits of -40 to +70 °C. Shock resistance is 12g for 11 ms, and vibration resistance is 7 mm at 2g — adequate for mounting on machinery with moderate vibration, though a direct-coupled pump or fan on a rigid base is the typical fit.
I/O, fieldbus, and connectivity
The starter communicates via AS-Interface protocol — no PROFIBUS DP or PROFINET on this variant. AS-Interface is a bit-level fieldbus suited for simple on/off control and status feedback from distributed devices; it carries the start/stop command and returns the overload trip signal and motor current data. Four digital inputs are integrated into the unit, allowing local pushbuttons or sensors to be wired directly without a separate I/O block. Device addressing is via an M12 plug, and the main current circuit connects through a HAN Q4/2 connector per ISO 23570 — a standard industrial rectangular connector for motor power. On-site operation is supported — meaning the starter can be manually operated via a local button or selector switch for commissioning and maintenance, independent of the fieldbus command.