The Siemens 5SL6663-7MB is a SENTRON miniature circuit breaker — 4-pole (3P+N), 63 A, C-curve, rated 400 V AC with a 6 kA breaking capacity per both EN 60898 and IEC 60947-2. That 6 kA rating means it safely interrupts fault currents up to that level in residential or light commercial distribution boards, and the C-curve (magnetic trip between 5 and 10× In) handles motor inrush and transformer loads without nuisance tripping. It occupies 4 modular-width units (72 mm) on a DIN rail, with a 76 mm depth that fits standard enclosures.
What the ratings mean for fit
The 63 A rating at 400 V AC, 50/60 Hz, covers main feeder or heavy branch circuits in residential and infrastructure panels. The 6 kA breaking capacity is standard for domestic and light commercial installations — adequate for most utility-side fault levels, but verify against your point-of-supply SCCR if feeding from a transformer. The C-curve characteristic suits loads with moderate inrush: small motors, pumps, compressors, and groups of lighting ballasts. The 4-pole (3P+N) design switches the neutral, which is required for TN-S or TT systems where the neutral must be isolated.
Mounting and integration
Snap-on DIN-rail mounting in any position. The 72 mm width (4 MW) and 76 mm depth match standard SENTRON panel cutouts. IP20 with connected conductors — suitable for enclosed distribution boards, not for wet or dusty locations. Sealable terminals allow lockout/tagout compliance. Supplementary devices (auxiliary contacts, shunt trips, alarm switches) can be added on the right side.
Environmental and compliance
Rated for ambient temperatures from -40 °C to +75 °C, with a mechanical service life of 20 000 operating cycles typical. Halogen-free and silicon-free construction. Overvoltage category III, pollution degree 2. Energy limitation class 3 — meaning it limits let-through energy well enough for most downstream equipment protection.