What this RCCB is and what the ratings mean for fit
The Siemens 5SM3615-0KK is a 2-pole residual current operated circuit breaker (RCCB) from the SENTRON 5SM3 series, designed for 230 V AC single-phase circuits. It is a type AC device, meaning it detects sinusoidal AC fault currents only — not pulsed DC or smooth DC faults. For a panel that sees variable-speed drives, switched-mode power supplies, or other non-sinusoidal leakage, a type A or type B RCCB would be needed instead. Rated current is 125 A; residual tripping current is 300 mA. Short-circuit breaking capacity is 10 kA at 230 V AC, overvoltage category III. Rated for 50 Hz only.
Mounting and integration into the panel
Mounts on DIN rail, occupies 2 width units, fits 70 mm installation depth. Mounting position is any; supply from top or bottom. Terminals accept 1.5 mm² to 50 mm² conductors. IP20 with distribution board installed and conductors connected. Finger and back-of-hand touch protection. Mechanical endurance is 10,000 switching cycles typical.