The Siemens 3RV6321-4AC10 is a SIRIUS circuit breaker designed for starter combinations — a motor-protective device that combines overload and short-circuit protection in a single 45 mm wide package. Rated 16 A at AC-3 duty (400 V), it handles motor switching up to that current, with an instantaneous magnetic short-circuit trip set at 208 A. That 208 A threshold means it clears faults fast enough to protect downstream contactors and cables without nuisance tripping on normal motor inrush.
Mounting and integration
Snap-on mounting onto 35 mm DIN rail per DIN EN 60715, with screw terminals for the main circuit accepting 2x (1…2.5 mm²) solid or stranded, or 2x (2.5…10 mm²). Size S0 frame — 45 mm wide, 97 mm tall, 96 mm deep — fits standard panel cutouts. Clearance requirements: 50 mm above and below, 30 mm to the side; zero forward or backward clearance needed. Mount in any position, ambient -20 to +60 °C operating.