The Siemens 5SM3612-6KL is a 2-pole residual current circuit breaker (RCCB) from the SENTRON 5SM3 series, rated 25 A at 230 V AC with a 300 mA type A residual trip. It is an instantaneous (short-time delayed: No) design, meaning it trips without intentional delay on a fault — critical for personnel protection where fast disconnection is required.
The IP20 protection class applies only when the distribution board is installed with connected conductors; the open unit is not touch-safe without the enclosure. Finger and back-of-hand safe construction meets the basic shock protection requirement during installation.
Type A fault current detection covers pulsating DC residual currents (typical from rectifiers, variable-speed drives, or switching power supplies) as well as sinusoidal AC — the standard choice for circuits with electronic loads. The 300 mA trip threshold is a fire-protection level (not personnel protection, which requires 30 mA or lower), suited for submain or feeder circuits where nuisance tripping from leakage is a concern but ground-fault protection is still needed.