The Siemens 5SM1647-6 is a 4-pole SENTRON residual-current circuit breaker (RCCB) rated 80 A at 400 V AC, 50 Hz, with a 300 mA Type A tripping characteristic and a 10 kA short-circuit current rating. Type A means it detects sinusoidal AC fault currents plus pulsating DC fault currents — the standard requirement for circuits with single-phase rectifiers, switched-mode power supplies, or variable-speed drives downstream. The 300 mA threshold is sized for equipment protection or fire prevention rather than personal shock protection (which typically calls for 30 mA or lower).
DIN-rail integration and conductor sizing
Mounts on DIN rail (REG) in any position, occupies 4 width units (roughly 72 mm), with an installation depth of 55 mm. Accepts solid or stranded conductors from 1.5 mm² up to 25 mm² — covers the full range from a 2.5 mm² lighting circuit tail up to a 16 mm² or 25 mm² main feeder.
Rated 80 A at both 40 °C and 45 °C ambient. Derating begins above 45 °C: 76.8 A at 50 °C, 73.6 A at 55 °C, 70.4 A at 60 °C, 67.2 A at 65 °C, and 64 A at 70 °C. The thermal curve is linear enough that a panel designer can interpolate for intermediate temperatures.