What it is and what it does
The Siemens SIRIUS 3RV1021-0FA10-0FJ0-ZX95 is a motor protection circuit breaker. It is rated for a continuous current of 0.5 A and carries a CLASS 10 trip class. Phase failure detection is built in, so if one leg drops out on a three-phase motor, this breaker will trip before the motor single-phases and burns up. That's a standard feature on SIRIUS breakers, not an add-on option.
Breaking capacity and coordination
Short-circuit breaking capacity is 100 kA at 400 V AC — the same rating holds at 240 V, 500 V, and 690 V AC. That's a full-range 100 kA rating, not a derated curve. For a 0.5 A breaker, this means it can sit upstream of a high-fault panel without needing a current-limiting fuse ahead of it, as long as the available fault current stays under 100 kA. Surge voltage resistance is rated at 6 kV.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. The 45 mm width takes one standard module slot. Depth is 96 mm, height 97 mm. Terminals are screw-type for the main circuit, accepting 2x (1 to 2.5 mm²) solid or stranded, or 2x (2.5 to 6 mm²). AWG equivalents are 2x (14 to 10). No auxiliary contacts are included — if you need a remote trip signal, you'll add the separate auxiliary switch block (confirms it's compatible).
Environmental and lifecycle
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. Shock resistance is 25 g for 11 ms. Mounting position is any. The front face carries an IP20 rating — protected against finger contact, not water ingress, so keep it inside a panel.