The Siemens 3RV1321-1KC10 is a SIRIUS circuit breaker designed specifically for starter combinations — motor-starting duty where the breaker provides both overload and short-circuit protection in a single device. Rated 12.5 A continuous current, it handles motor loads up to 5.5 kW at 400 V AC, with a 100 kA breaking capacity at that voltage. That 100 kA SCCR means it can safely interrupt a bolted fault on a high-capacity distribution bus without upstream fuses needing to clear — a real advantage in panel designs where coordination is tight.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail per DIN EN 50022. The 45 mm width and 97 mm height fit standard enclosure rail spacing; 96 mm depth leaves clearance for wiring behind the panel door. Any mounting position is allowed, so orientation in a crowded cabinet isn't a constraint. Main circuit connections are screw-type terminals accepting solid or stranded conductors: 2x (1 to 2.5 mm²) or 2x (2.5 to 6 mm²) per pole. AWG equivalents are 2x (14 to 10). The front face carries an IP20 rating — safe for finger-probe access in a closed panel, but not for washdown environments.
Breaking capacity across voltage
Breaking capacity varies with line voltage: 100 kA at 240 V and 400 V AC, derating to 42 kA at 500 V AC, and 6 kA at 690 V AC. At 690 V the fault-current capability drops sharply — verify your available fault current at that voltage before specifying. The rated impulse withstand voltage is 6 kV, with a rated insulation voltage of 690 V.