The Siemens SIRIUS 3RV1011-1FA10-ZI45 is a motor protection circuit breaker in size S00, rated for 5 A operating current with an adjustable overload release covering 3.5 to 5 A. The magnetic short-circuit release is fixed at 65 A (the N release), so it clears hard faults upstream of the motor starter. Clearance distances are 20 mm upwards and downwards, 9 mm to the side, and 0 mm forwards and backwards — meaning you can butt it against the back panel or adjacent devices without extra spacing on those faces.
Integration note
Size S00 is the smallest frame in the SIRIUS 3RV1 family — 45 mm wide, 75 mm deep, 90 mm high. It snaps onto the same 35 mm DIN rail as contactors and overload relays, and Siemens publishes a combination table for direct mounting with S00 contactors (e.g., 3RT2 series) without additional wiring between the breaker and contactor. The power loss at rated current is 7.25 W total (2.4 W per pole), so no special ventilation is needed in a standard IP20 enclosure.
The breaker is designed for motor protection per IEC 60947-2 and -4, with thermal overload and magnetic short-circuit release built in — no separate overload relay needed for the motor branch.