What this part is and what it does
The Siemens SENTRON 5SU9326-1CN32 is a 2-pole RCD-operated circuit breaker (RCBO) that combines overcurrent protection and residual current protection in a single 4-MOD unit. It is rated for 32 A at AC with a C tripping characteristic, meaning it handles moderate inrush currents typical of motor and lighting loads on a final subcircuit. The breaking capacity is 6 kA per EN 60898 and IEC 60947-2, so it can safely interrupt faults up to that level in a domestic or light commercial distribution board.
Key ratings and what they mean for fit
The 32 A rating is the continuous current at 30 °C ambient. At 40 °C it derates to 29.1 A, at 45 °C to 27.8 A, at 50 °C to 26.6 A, and at 55 °C to 25 A — so if the panel runs hot, size up accordingly. The C-curve trips magnetically between 5 and 10 times rated current, which suits loads like small motors, pumps, and fluorescent lighting that draw a brief start surge. The RCD element is type AC, meaning it detects sinusoidal AC fault currents only — not pulsed DC or smooth DC faults. If the downstream equipment includes VFDs, LED drivers, or rectifiers, a type A or B RCD would be needed instead.
Mounting and wiring
The 5SU9326-1CN32 snaps onto a DIN rail, occupies 4 width units (72 mm), and has an installation depth of 70 mm plus the device depth of 77 mm. It accepts solid or stranded conductors from 0.75 to 35 mm², so it handles both thin control wiring and heavier power tails. The supply can enter from the top or bottom, which helps when the busbar arrangement in the panel dictates the feed direction. Mounting position is any orientation. IP20 protection applies once the distribution board is installed and conductors are connected — treat it as a panel-internal device, not for wet or dusty environments.