The Siemens SENTRON 5SV3612-3 is a 2-pole residual current circuit breaker (RCCB) rated for 25 A at 230/400 V AC, 50/60 Hz. It detects Type F fault currents — the waveform that covers standard sinusoidal AC plus mixed-frequency residual currents from variable-speed drives and power electronics. That makes it the right choice for circuits feeding VFDs, UPS systems, or any load where the fault signature isn't a clean 50 Hz sine wave.
Surge current resistance is 3 kA, and the I²t withstand is 58 000 A²·s, which tells you the device handles high-energy let-through without welding its contacts. The short-time delayed design (Type F with intentional delay) means it rides through brief inrush or transient leakage that would nuisance-trip a standard instantaneous RCCB. That's useful on circuits with capacitive input filters or soft-starters that generate a short pulse of leakage at power-up.
Snaps onto a DIN rail (REG profile), occupies 2 width units (36 mm), and accepts conductors from 0.75 mm² up to 35 mm² solid or stranded. Finger and back-of-hand safe protection against accidental contact with live terminals.