What this MCCB is and where it lands
The Siemens SIRIUS 3RV1373-7JN10 is a molded-case circuit breaker (MCCB) designed specifically for starter combinations — meaning it's the short-circuit and overload protection piece ahead of a contactor in a motor control center or standalone panel. Rated 630 A continuous and 200 kW at 400 V AC, it handles large induction motors, pumps, compressors, and conveyor drives in industrial plants. The 120 kA breaking capacity at 400 V AC is the headline number: that's the fault current it can safely interrupt without welding contacts or venting plasma into the enclosure. For a 480 V plant, the 85 kA at 500 V and 70 kA at 690 V give you selectivity headroom downstream.
Key ratings — what they mean for fit
The 630 A continuous rating at 40 °C ambient is the thermal limit for the main contacts; above that, you need to derate per the manufacturer's curve. The AC-3 operational current at 400 V is also 630 A — that's the motor-switching duty, making this breaker a direct fit for a 630 A motor branch circuit without oversizing. The electronic short-circuit trip gives adjustable magnetic pickup, which helps coordinate with downstream contactors and avoid nuisance trips on inrush. The 15 operations per hour maximum at AC-3 is a duty-cycle limit — not a continuous-switching device; it's meant for occasional motor starts, not frequent cycling. The 20–690 V rated voltage range covers low-voltage industrial systems worldwide — 208 V, 240 V, 400 V, 480 V, 600 V, and 690 V all fall inside. The surge voltage resistance of 8 000 V (impulse withstand) means it can handle switching transients on a 690 V line without internal flashover. The IP20 front protection is typical for panel-mounted breakers; the enclosure provides the real ingress protection.
Mounting and integration
Screw fixing to a mounting plate or backpanel — no DIN rail for this frame size. The 140 mm width, 205 mm height, and 103.5 mm depth fit a standard motor control center bucket or a standalone enclosure. Zero clearance required at the back and sides simplifies panel layout; you can butt it against adjacent devices without derating for heat buildup. The screw-type terminals on both main and auxiliary circuits accept lugged cable up to the rated cross-section. Any mounting position is allowed, which helps in tight retrofit situations where the panel orientation is fixed.
Compliance and approvals
The part carries RoHS substance prohibitance dated 01/08/2008, compliant with the EU directive. The finger-safe touch protection (IP20 front) meets IEC 60529 for operator safety in open panels. No ground fault or phase failure detection built in — that's handled by the upstream protection or a separate relay. The electronic trip design is inherently more precise than thermal-magnetic for coordination studies.