The Siemens SIRIUS 3RV1021-4DA10-ZW95 is a 3-pole motor protection circuit breaker rated for 25 A continuous current and 11 kW at 400 V AC. It carries a Class 10 trip characteristic, meaning it will disconnect within 10 seconds at 7.2× the thermal setting — fast enough to protect standard induction motors during a stall or locked-rotor event without nuisance tripping on normal starting inrush. Breaking capacity sits at 50 kA at 400 V AC, which covers most industrial distribution panels up to that fault level without needing an upstream current-limiting fuse. At 690 V it still interrupts 4 kA, so it can serve 690 V motor circuits in regions where that line voltage is standard. Mounts via screw and snap-on onto 35 mm DIN rail per EN 50022, with zero clearance needed at the sides or rear — panels stay tight. The front face carries IP20 touch protection; the screw terminals accept 1–6 mm² solid or stranded conductors.
Key Ratings & What They Mean
Phase failure detection is built in — if one line drops, the breaker trips, preventing single-phasing damage to the motor. No ground-fault detection on this variant, so a separate ground-fault module or RCD is needed if that protection is required. The 25 A continuous rating is the thermal setting range; the actual adjustable overload relay inside the breaker is set to match the motor FLA. Trip Class 10 pairs with standard IEC and NEMA Design B motors — the 10-second window at 7.2× FLA is the typical benchmark for motor protection coordination. Rated insulation voltage is 690 V, and surge voltage withstand is 6 kV, so it can be used in 400 V or 690 V systems without additional series protection for impulse voltage events. Power dissipation at rated current is 10.5 W total (3.5 W per pole) in hot operating state — factor that into enclosure thermal calculations if the panel is densely packed.
Integration Notes
Screw terminals on both main and auxiliary circuits. Main contacts accept 2× (1–2.5 mm²) or 2× (2.5–6 mm²) solid or stranded — strip length is standard 8–10 mm for screw clamps. Auxiliary switch extension is supported (product extension auxiliary switch = Yes), so a separate 3RV19xx auxiliary contact block can be snapped onto the side for remote status indication. Mounting position is any orientation. Ambient operating range is -20 to +60 °C; storage and transport range is -50 to +80 °C. Shock rated at 25g for 11 ms — suitable for machine-mounted applications with moderate vibration. Maximum switching frequency under AC-3 duty is 15 operations per hour — fine for motor starting on pumps, fans, or compressors; not intended for high-cycling applications like rapid reversing or jogging.