The Siemens SIRIUS 3RV1021-1EA10-ZX95 is a motor protection circuit breaker rated for 4 A continuous current and 1.5 kW at 400 V AC-3 duty. It snaps onto a 35 mm DIN rail per EN 50022 and uses screw-type terminals for both main and auxiliary circuits. The Class 10 trip characteristic means it clears overloads fast enough to protect standard induction motors during startup — a 7.25 W power dissipation at full load tells you the thermal budget inside a crowded panel is manageable.
Compared to the 3RV2021-1FA15, the 3RV1021-1EA10-ZX95 is the lower-current sibling — 4 A versus the 2021's higher rating. Both share the SIRIUS form factor and screw-terminal design, so they swap into the same DIN-rail footprint without rewiring the panel. The difference is the motor load they protect: this one handles smaller motors up to 1.5 kW at 400 V; the 2021 steps up for bigger drives.
Mounting position is any orientation; the 45 mm width leaves room for adjacent breakers on the same DIN rail. Wire the main circuit with 1 to 6 mm² solid or stranded conductors (AWG 14-10), and the auxiliary contacts with the same range. The screw terminals accept ferruled stranded wire with core-end processing. No backward clearance needed at the rear — 0 mm — so it sits flush against the backplane.
Breaking capacity hits 100 kA at 240 V, 400 V, and 500 V AC, then drops to 6 kA at 690 V AC. That 100 kA rating at 400 V is high enough for most industrial distribution panels without upstream current-limiting fuses. Phase failure detection is built in; ground fault detection is not — plan external GF protection if the application requires it. Shock resistance rated at 25g for 11 ms, so it holds up in high-vibration environments like conveyor drives or compressor skids.