The Siemens SIRIUS 3RV1021-1HA10-0FJ0-ZX95 is a motor protection circuit breaker rated for 8 A continuous current, sized for a 3 kW motor at 400 V AC. The CLASS 10 trip characteristic means it disconnects within 10 seconds at 7.2× the thermal setting — fast enough to protect a standard induction motor during a locked-rotor event without nuisance tripping on normal starting inrush.
Breaking capacity and fault coordination
This breaker delivers 100 kA breaking capacity at 240 V AC and 400 V AC, 42 kA at 500 V AC, and 6 kA at 690 V AC. At 400 V — the most common industrial motor supply — the 100 kA figure means it can safely interrupt a bolted fault up to that level without requiring an upstream current-limiting fuse for most installations. The 6 kA at 690 V still covers typical fault levels on 690 V systems, but verify the prospective short-circuit current at the point of installation.
Mounting and panel integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. The 45 mm width and 97 mm height fit a standard 45 mm modular device footprint; depth is 96 mm including the screw terminals. Any mounting position is permitted. The IP20 front protection means it's suitable for enclosed panel installation only — not for washdown or outdoor exposure without an additional enclosure.
Termination and wiring
Main current circuit terminals are screw-type, accepting 2× (1 to 2.5 mm²) solid or stranded, or 2× (2.5 to 6 mm²) — equivalent to 2× (14 to 10 AWG). The dual-conductor capacity per clamp is useful when looping through to a downstream contactor or overload relay without an additional terminal block. Backwards and side clearances are zero, so adjacent devices can mount flush.
Environmental and mechanical ratings
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. Shock resistance is 25g for 11 ms, and surge voltage resistance is rated at 6 000 V. Maximum operating altitude is 2 000 m without derating. The mechanical endurance of the main contacts is 100 000 operations typical.
Protection features and auxiliary contacts
Phase failure detection is built in — the breaker trips on loss of any phase, preventing single-phasing damage to the motor. Ground fault detection is not included. The unit has no factory-fitted auxiliary contacts (0 auxiliary contacts), but an auxiliary switch option is available as an add-on accessory. Trip class is CLASS 10, and the maximum switching frequency at AC-3 duty is 15 operations per hour.