What the ratings mean for fit
The 5SY8432-8: The D-curve means the magnetic trip threshold is 10–20× In, so it holds through the startup surge of a 32 A motor or a bank of switched-mode supplies without dropping out. At 32 A rated current, it's sized for a 3-phase load drawing about 22 kW at 400 V. The 30 kA breaking capacity at 400 V AC per IEC 60947-2 certifies it can safely interrupt a fault current up to that level — critical for industrial panels where the prospective short-circuit current can be high. The 15 kA DC rating at 72 V max covers control-circuit protection in DC bus applications, though it's primarily an AC breaker. Temperature derating is built in: at 45 °C it still carries the full 32 A, but at 55 °C it's 30.37 A, and at 50 °C it's 31.2 A (–). If the panel ambient runs hot, factor that into the load calculation. The IP20 rating with connected conductors is standard for enclosed distribution boards — not for wet or dusty locations without a cabinet.
Panel integration and mounting
Snaps onto DIN rail via the quick assembly system, occupies 4 modular width units — that's 72 mm wide. Mounting position is any, so vertical or horizontal orientation is fine. Installation depth is 70 mm; overall depth is 76 mm. Combined terminals top and bottom accept both busbar and cable, which saves time on the rail. Pollution degree 3 means it's rated for conductive pollution typical in industrial panels — no special coating needed for normal factory air.
Lifecycle and sourcing reality
Current-production part in the Siemens SENTRON family. No LTB or phase-out notice. Standard order item sourced through independent distribution; availability and pricing confirmed at quote time.
Compliance and documentation
The 5SY8432-8 carries the SENTRON brand designation and is classified per EN 61346-2 and IEC 81346-2 as function F. It's halogen-free and silicon-free, which matters for outgassing-sensitive environments like clean rooms or sealed enclosures. Vibration resistance tested per IEC 60068-2-6 — ±1 mm at 5–25 Hz, 50 m/s² at 25–150 Hz — so it holds up on machinery with moderate vibration. The sealable feature allows tamper-proof locking of the toggle, useful for critical circuits.