What it is and what it does
The Siemens SIRIUS 3RV1011-1FA20-ZX95 is a motor protection circuit breaker rated for 5 A continuous current. It's built for a 3-phase motor circuit — three poles on the main current path, spring-loaded terminals for both power and control wiring. The CLASS 10 trip curve means it will open within 10 seconds at a locked-rotor current, which covers most standard induction motor starts without nuisance tripping. Phase failure detection is built in, so if one line drops, the breaker trips and protects the motor from single-phasing. The 100 kA breaking capacity at 400 V AC means it can interrupt a fault current up to that level without welding contacts or cascading failure upstream — important when you're coordinating with a feeder breaker.
Mounting and wiring — fits where it needs to
Snaps onto 35 mm DIN rail per DIN EN 50022. Width is 45 mm, depth 81 mm, height 90 mm. Zero clearance needed at the back or sides — you can pack these tight in a panel. Mounting position is any orientation. Spring terminals on the main circuit accept 2x (0.25... 2.5 mm²) solid or 2x (0.25... 1.5 mm²) finely stranded with ferrules. AWG equivalent is 2x (24... 14). No screwdriver torque to worry about — strip, insert, done. The IP20 finger-safe front means you can work in a live panel without exposed metal.
Breaking capacity and coordination
The 100 kA rating holds at both 240 V and 400 V AC. At 500 V it drops to 3 kA, and at 690 V to 2 kA. That's typical for this frame size — the arc energy scales with voltage. For a 400 V panel with high fault current (say a transformer-fed MCC), this breaker handles it. For 690 V industrial systems, you'll need to check the available fault current against the 2 kA limit. Surge voltage withstand is 6 000 V. The 7.25 W power loss in hot operating state matters for thermal management.