What this RCBO does in the panel
The Siemens 5SU9346-1CR32 is a 4-pole RCBO (residual-current-operated circuit breaker with overcurrent protection) from the SENTRON family, combining a 32 A thermal-magnetic trip (C-curve) with a 30 mA type AC residual-current device in one 7-module-wide unit. The 30 mA trip threshold protects against direct-contact shock risk in standard AC circuits (sinusoidal residual currents only — not pulsed DC or smooth DC, which is the type AC limitation).
Thermal derating — the real-world current limit
At 30 °C ambient the device carries its full 32 A. At 40 °C it derates to 29.8 A; at 45 °C to 28.5 A; at 50 °C to 27.8 A; at 55 °C to 27.2 A. If the distribution board runs warm — common in a packed enclosure — the continuous load must stay below the derated value. The C-curve (magnetic trip at 5–10× In) handles motor inrush and transformer energization without nuisance tripping, but the thermal element follows the derating table.
Width is 126 mm (7 modular width units). Height is 90 mm.
Coordination and selectivity context
Energy limitation class 3 limits let-through energy for downstream cable protection. The 4 kV rated surge voltage matches overvoltage category III requirements. Insulation voltage is 440 V.