SIRIUS 3RV6321-4CC10 — motor branch circuit breaker for starter combinations
The Siemens 3RV6321-4CC10 is a SIRIUS circuit breaker designed specifically for starter combinations — meaning it integrates the motor-protective and short-circuit functions into one device ahead of a contactor, saving panel space over a fused disconnect plus separate overload relay. Rated 22 A in AC-3 duty at 400 V, so it handles motor loads up to that current — typical for a 7.5 kW to 11 kW induction motor depending on service factor. The instantaneous short-circuit trip fires at 286 A, clearing faults before the contactor welds. Mounts on 35 mm DIN rail per DIN EN 60715 via the integrated snap-on foot, or screws directly to a backplate. The Size S0 frame (45 mm wide, 96 mm deep, 97 mm tall) fits standard 45 mm module spacing — one slot on the rail. Screw-type terminals on top and bottom accept 2x 1–2.5 mm² solid/stranded or 2x 2.5–10 mm², with a tightening torque of 2–2.5 N·m. The magnetic short-circuit trip is non-adjustable; the thermal overload element is set by the factory to the 22 A rating.
Clearance and integration
Requires 50 mm clearance above and below the device, 30 mm at the sides, and zero forwards or backwards — so it fits tight against the backpanel or enclosure wall. Mounting position is any, which simplifies layout in crowded panels. Total power loss is 8 W typical. Operating temperature range is -20 to +60 °C; storage range -50 to +80 °C. Rated insulation voltage 690 V AC at pollution degree 3, surge voltage resistance 6 kV — suitable for 400/480 V line-to-line systems with adequate clearance. Shock resistance 25g / 11 ms per IEC 60068-2-27.
Lifecycle and compliance
RoHS compliance date is 05/01/2012. The part carries the SIRIUS brand.