The Siemens 5SM3312-6KL12 is a SENTRON residual current circuit breaker (RCCB) — 2-pole, Type A, rated 25 A at 230 V AC with a 30 mA trip threshold. The N-left variant means the neutral conductor connects on the left side of the device, which matters when laying out busbars or pre-wired panels.
Type A detection covers sinusoidal AC faults plus pulsating DC faults up to 6 mA of smooth DC superimposed, which is the minimum for modern electronics (switched-mode supplies, variable-speed drives) that generate pulsating leakage. Ambient temperature range of -25 to +45 °C covers unheated enclosures in most climates; above 45 °C you need to derate or move to a higher-rated device.
Mounts on DIN rail (REG) in any position — top or bottom supply connection accepted. Terminals accept solid or stranded conductors from 1 to 16 mm², with a tightening torque of 2.5 to 3 N·m.