What it is and what it protects
The Siemens SIRIUS 3RV1021-0HA10-0FJ0 is a motor protection circuit breaker designed for protecting three-phase motors against overload and short-circuit. Its 0.8 A rated continuous current sets the motor full-load current it can handle continuously without tripping. Trip class 10 means it will trip within 10 seconds at 7.2× the current setting — fast enough to protect standard induction motors during a locked-rotor event, without nuisance tripping on normal starting inrush. Phase failure detection is built in, so a lost phase on the line side will cause the breaker to open, preventing single-phasing damage to the motor. The breaking capacity is 100 kA at 400 V AC and holds at 500 V and 690 V AC — that is a high short-circuit withstand for a 0.8 A device, meaning it can clear a fault on a high-capacity distribution panel without upstream fuse coordination issues.
Mounting and panel fit
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 module footprint, and the 96 mm depth leaves clearance behind the rail for wiring. Any mounting position is allowed, so it can be oriented horizontally or vertically in the panel to suit wire routing. The front face carries IP20 finger protection; the terminals are screw-type for the main circuit, accepting solid or stranded conductors from 1 to 6 mm² (two per terminal).
Environmental and mechanical tolerance
Operating temperature range is -20 to +60 °C, with storage and transport rated from -50 to +80 °C. Shock resistance is 25 g for 11 ms, which covers most industrial vibration environments. Maximum operating altitude is 2 000 m without derating. The auxiliary switch is present for remote status indication; no ground fault detection on this variant.
Lifecycle and sourcing
For a BOM freeze or replacement planning, the 3RV1011-0GA10 and 3RV1011-0HA10 are smaller-frame siblings in the same SIRIUS family — same Class 10 trip, but different current ranges and breaking capacities. The 3RV6011-0CA10 is a different series with different mounting and ratings. The 3RV1021-0HA10-0FJ0 is the correct 0.8 A, 100 kA variant.