The Siemens 5SM9326-0 is a SENTRON residual-current unit (RC unit) designed as an electronic add-on for the 5SL4 miniature circuit breaker. It provides earth-leakage protection in a 2-pole, type AC configuration, rated at 63 A and 30 mA tripping current on a 400 V AC, 50 Hz supply. The unit is instantaneous — no intentional delay — so it trips within the first cycle on a sinusoidal AC fault. Mounting is standard rail (DIN) with a 36 mm width (2 MW). The unit sits above the MCB, fed from the top. Terminal torque is 2.5–3 N·m; solid conductors up to 35 mm² and stranded up to 25 mm² are accepted.
Because this is an RC unit that mates mechanically and electrically with the 5SL4 miniature circuit breaker, the panel layout must place the 5SM9326-0 directly above the 5SL4 on the same DIN rail. The supply cord connects to the top terminals; the MCB feeds the load side below. Verify that the 5SL4 breaker is the correct base unit — the 5SM9326-0 is not a standalone device and will not function without its paired MCB.