The Siemens 5SM1616-0 is a SENTRON 5SM1 series residual current circuit breaker (RCCB) — 2-pole, type AC, rated 63 A at 230 V AC with a 300 mA residual trip threshold. Instantaneous tripping characteristic, no short-time delay. This is the part that sits downstream of the main breaker to protect against earth faults in single-phase AC circuits.
Above 45 °C the derating curve kicks in: 60.48 A at 50 °C, stepping down to 50.4 A at 70 °C (–). The 300 mA residual trip is an equipment-protection level, not personnel protection (that's 30 mA); it's sized to catch insulation degradation on motor feeders or distribution subcircuits before it escalates. Not suitable for pulsating DC or smooth DC faults — those require type A or type B RCCBs. For standard single-phase lighting, heating, and motor circuits with no rectifiers or VFDs downstream, type AC is the common choice.
Snap-on DIN rail (REG) mount, 2 module width units, 55 mm installation depth. Mounting position any — horizontal or vertical orientation doesn't affect the trip mechanism. Supply connection from top or bottom. IP20 with conductors connected and distribution board installed — it's an enclosed-panel part, not for open wet locations. Finger and back-of-hand safe touch protection — the terminals are shrouded to IP20 touch-safe standards once wired. Silicon-free construction relevant for potting or conformal-coating environments where silicone outgassing can cause contact contamination.