Motor protection circuit breaker for 1.25 A loads
The Siemens SIRIUS 3RV1011-0KA10-0FJ0-ZX95 is a motor protection circuit breaker rated for a continuous current of 1.25 A and a CLASS 10 trip characteristic, meaning it will trip within 10 seconds at 7.2× the set current — fast enough to protect standard induction motors during locked-rotor events without nuisance tripping on normal starts. Its breaking capacity reaches 100 kA at 400 V AC (and at 240 V and 500 V AC as well), dropping to 2 kA at 690 V AC — so in a 400 V panel this breaker can interrupt fault currents up to 100 kA without upstream fuses, which simplifies coordination in high-fault installations. Phase failure detection is built in, so the breaker will trip if one phase drops out — a common cause of single-phasing motor damage. No ground-fault detection on this variant.
Mounting and panel integration
Mounts via screw or snap-on onto a 35 mm DIN rail per EN 50022. Dimensions are 45 mm wide, 90 mm high, 81 mm deep — a compact footprint that leaves room for adjacent contactors or auxiliaries in a motor control center. Front-face protection is IP20, suitable for enclosed panel use; no washdown rating. Any mounting position is allowed. Terminals accept solid or stranded conductors: 2× (0.5…1.5 mm²) and 2× (0.75…2.5 mm²) per pole, with AWG equivalents 2× (18…14) for the main circuit. Screw-type terminals for the main circuit.
Environmental and mechanical ratings
Operates from -20 to +60 °C, stores and transports from -50 to +80 °C. Shock rated at 25g for 11 ms. Maximum operating altitude 2 000 m. Surge voltage resistance rated at 6 000 V. Power dissipation at rated current in hot state is 5.5 W total, 1.8 W per pole. Mechanical endurance of the main contacts is typically 100 000 operations. Maximum switching rate at AC-3 duty is 15 operations per hour.