Motor Protection Circuit Breaker — 25 A, Class 10, 50 kA SCCR
The Siemens 3RV1021-4DA10-ZX95 is a SIRIUS motor protection circuit breaker (MPCB) rated for 25 A continuous current, with a Class 10 trip characteristic for standard motor starting duty. At 400 V AC-3 it handles 11 kW loads, and the interrupting rating sits at 50 kA at 400 V AC — enough to clear a fault without upstream coordination in most distribution panels. Phase failure detection is built in; no ground fault detection on this variant. Mounts via screw and snap-on onto 35 mm DIN rail per EN 50022. The front face carries IP20 protection — adequate for enclosed panel use, not for washdown zones. Screw-type terminals on the main circuit accept 2x (1…2.5 mm²) solid or 2x (2.5…6 mm²) stranded, with AWG equivalents at 2x (14…10).
Installation & Integration
The breaker occupies 45 mm width on the DIN rail, with 96 mm depth and 97 mm height. Zero clearance required at the sides or rear — 0 mm backwards and 0 mm at the side — so it fits tight panel layouts. Operating temperature range is -20 to +60 °C; storage and transport from -50 to +80 °C. Shock rated at 25g for 11 ms. Mounting position is unrestricted.
Coordination & Ratings
The interrupting capacity steps down with voltage: 100 kA at 240 V AC, 50 kA at 400 V, 10 kA at 500 V, and 4 kA at 690 V. Rated impulse withstand voltage is 6 kV. Power dissipation at rated current in hot operating state is 10.5 W total, 3.5 W per pole. Mechanical endurance on the main contacts is 100,000 operations typical. An auxiliary switch is included as standard (0 auxiliary contacts for the main circuit — the auxiliary switch is a separate integrated unit). The maximum switching frequency at AC-3 duty is 15 operations per hour.