The Siemens 5SM3111-6KL is a SENTRON residual current operated circuit breaker (RCCB), 2-pole, Type A, rated 16 A at 230 V AC, 50 Hz, with a 10 mA tripping residual current. The N-left variant means the neutral connection is on the left side of the device — a detail that matters when swapping into an existing panel layout without re-dressing the wiring.
The 10 mA trip threshold (Type A) catches pulsating DC fault currents on top of sinusoidal AC — common in modern loads with rectifiers, switching power supplies, or variable-speed drives. That's a tighter threshold than the standard 30 mA RCCB, so it's specified where personnel protection against ventricular fibrillation is the priority (e.g., wet locations, medical rooms, or portable equipment in industrial settings). The 16 A rated current matches the load side of a 16 A MCB in a sub-distribution board; you'd pair it downstream of a 16 A or 20 A miniature circuit breaker for coordinated overcurrent and earth-fault protection. Instantaneous design (no short-time delay) means it trips within a cycle on a residual fault — no intentional delay for selective coordination with downstream RCDs. That's the right choice for final circuits where speed matters more than discrimination.
IP20 with connected conductors — fine for indoor panel use, not for wet washdown zones.