Siemens 5SU9356-7KK32 is a SENTRON RCBO — an RCD-operated circuit breaker combining overcurrent and residual-current protection in one 2-module-wide (36 mm) package. Rated 32 A at AC with a C-curve trip characteristic and 30 mA Type A residual sensitivity.
What the ratings mean for fit
The 32 A rating at 30 °C is the headline figure, but the real-world capacity drops with ambient temperature: 30.08 A at 40 °C, 29.12 A at 45 °C, 27.84 A at 50 °C, and 25.92 A at 55 °C. If the panel runs warm — common in a crowded enclosure — size the load to the derated value, not the 30 °C number. Type A residual detection trips on sinusoidal AC faults and pulsating DC faults up to 30 mA — the standard choice for circuits with single-phase rectifiers or switched-mode power supplies. The 1P+N design protects only the live pole; the neutral is switched but not protected. Overvoltage category III and pollution degree 2 suit fixed-installation distribution boards. Mounting position is unrestricted, and supply can enter from top or bottom — useful when retrofitting into an existing board with fixed busbar orientation.
Panel integration and footprint
Two modular width units (36 mm) snap onto standard DIN rail. Installation depth is 70 mm plus the 77 mm overall depth — check the gland plate clearance if the board is shallow. IP20 only when the distribution board is installed and conductors are connected; handle as a live component during wiring.