Safety-rated direct starter for small motor loads
The Siemens 3RA7141-1AA17-0AB4 is a SIRIUS safety load feeder configured as a direct starter, meaning it combines a contactor, overload relay, and short-circuit protection into a single unit for controlling and protecting a motor branch circuit. Rated for a 0.55 kW motor at 400 V AC-3 duty, it handles a motor current of 1.5 A, with the thermal overload release adjustable from 1.1 to 1.6 A to match the motor's full-load current. The control voltage is 24 V DC, so it integrates directly into a standard 24 V DC control circuit without needing an additional power supply conversion.
Cat 4 / SIL 3 — what the safety ratings mean for the circuit
This unit carries Category 4 per EN 954-1 and Safety Integrity Level 3 per IEC 61508, which means it is designed for the highest level of fault tolerance and diagnostic coverage in a safety-related control system. In practice, Cat 4 / SIL 3 allows the load feeder to be used in safety circuits where a single fault cannot lead to a loss of the safety function, and where the fault is detected at or before the next demand — typical for guarding applications, emergency stop circuits, and light curtain interfaces. The cascading design (yes) means multiple units can be linked to extend the safety function across several motor starters without adding external safety relays.
Mounts via screw and snap-on onto a 35 mm standard mounting rail, occupying the S00 footprint — 90 mm wide, 211 mm tall, 113 mm deep.