Siemens SENTRON 5SY8432-8BB08 — 4-pole D-curve MCB, 30 kA IEC breaking capacity
The Siemens SENTRON 5SY8432-8BB08 is a 4-pole miniature circuit breaker with a D tripping characteristic, rated for 400 V AC (multi-phase) and 440 V AC single-phase operation at 50/60 Hz. Its 30 kA breaking capacity per IEC 60947-2 at 400 V AC means it can safely interrupt high fault currents in industrial distribution — the D curve provides a higher magnetic trip threshold (10–20× In), suited for loads with high inrush such as motors, transformers, or welding equipment where a B or C curve would nuisance-trip on startup. The breaker occupies 4 modular width units (72 mm wide, 90 mm tall, 76 mm deep) and snaps onto a DIN rail via the quick assembly system — any mounting position is permitted. IP20 protection (with connected conductors) is standard for enclosed panel use. Vibration resistance per IEC 60068-2-6 covers ±1 mm at 5–25 Hz and 50 m/s² at 25–150 Hz, making it suitable for machinery mounted on vibrating equipment. The unit is halogen-free and silicon-free, and its sealable design supports tamper-evident locking for compliance-sensitive installations. Pollution degree 3 and overvoltage category III ratings confirm it for fixed industrial panels where conductive pollution or transient overvoltages are expected.
Lifecycle & sourcing — active production, quoted to order
The breaker accepts plug-in auxiliary devices (shunt trip, alarm switch, auxiliary contact) via the product extension interface, allowing field-configurable signaling without replacing the base unit.
Integration notes — DIN-rail fit and ambient derating
Mounts on standard 35 mm DIN rail; the 72 mm width (4 MW) matches the SENTRON modular grid. Installation depth is 70 mm, leaving clearance behind the panel for wiring. The combined terminal top and bottom accept supply from either direction — no polarity concern on AC. Ambient temperature range is -40 °C to +75 °C, with humidity limits: max 95% RH at 55 °C, derating to 35% RH at 75 °C. Power loss per pole at rated current in hot state is 2.1 W — account for heat buildup when ganging multiple breakers in a closed enclosure.
Regulatory & compliance — approvals and documentation
Rated per IEC 60947-2 (30 kA at 400 V AC) and also carries a 5 kA rating per UL 1077 / CSA C22.2 No. 235 for North American supplementary protection applications. The DC rating is limited to 72 V maximum — not a general-purpose DC breaker for higher voltages. The product is halogen-free and silicon-free, meeting common environmental compliance requirements for industrial equipment. Documentation (datasheet, CE declaration, RoHS/REACH statements) is available on request.