What this SIRIUS S3 motor starter is
The Siemens 3RA1145-4LB46-1AV6 is a SIRIUS non-fused motor starter in Size S3 — a direct-starter assembly that combines a circuit-breaker and contactor in one DIN-rail footprint, saving panel space over discrete components. Rated 45 kW at 400 V AC-3 (75 hp at 460/480 V), it handles standard three-phase induction motors up to that load without an external overload relay — the integrated overload protection is set for Trip Class 10, meaning it trips fast enough to protect the motor during a stalled-rotor start without nuisance tripping on normal acceleration. The assembly ships with a 3RT1046-1AV60 contactor and a 3RA1941-1AA00 link module pre-wired, so it arrives as a tested, coordinated pair — no guessing on short-circuit coordination between the breaker and contactor.
Minimum clearances: 90 mm above, 10 mm below, and 12 mm to the side for airflow and arc-chamber venting. Zero clearance needed forward or backward, so you can butt it against a backplate or door. Main power terminals accept stranded wire from 2.5 to 70 mm² (or two conductors 10–50 mm² each), which covers the full ampacity range for a 45 kW motor feeder.