The Siemens 5SM9333-0 is a SENTRON residual current (RC) unit designed as a companion for the 5SL4 miniature circuit breaker. It is a 3-pole, type AC device rated at 40 A with a 30 mA tripping residual current, operating at 400 V AC, 50 Hz. This combination — an RC unit paired with an MCB — provides both overcurrent and earth-fault protection in a single DIN-rail assembly, commonly used in final distribution boards in commercial and residential infrastructure.
The 40 A rated current and 30 mA residual sensitivity define the protection envelope: 40 A matches the upstream MCB or load capacity, while 30 mA is the standard threshold for personal protection against indirect contact in TN and TT systems. For circuits with rectifiers, VFDs, or switched-mode supplies, a type A or F RC unit would be required. The 3 kA surge current resistance indicates the unit can withstand transient overcurrents without nuisance tripping, which is typical for RC units paired with MCBs. The mechanical service life of 10 000 switching cycles is standard for this class of device and sufficient for normal distribution panel operation. Conductor termination accepts solid conductors from 0.75 to 35 mm² and stranded from 0.75 to 25 mm², with a tightening torque of 2.5 to 3 N·m. This range covers most final-circuit wiring sizes up to 35 mm², which is adequate for 40 A circuits.
The supply connection is at the top, above the miniature circuit breaker.