The Siemens 5SM3342-3 is a 4-pole SENTRON residual-current circuit breaker (RCCB) rated for 25 A at 400 V AC, 50 Hz, with a 30 mA residual trip threshold and Type F fault-current sensitivity. Type F means it detects AC residual currents plus pulsating DC and high-frequency AC from variable-speed drives, so it is the right choice on circuits feeding single-phase VFDs, washing machines, or heat pumps where a standard Type A would miss the HF component. The short-time delayed design provides selectivity against nuisance tripping from downstream transient leakage — useful on distribution subfeeds feeding multiple loads.
Snap-on DIN rail (REG) mounting, 4 width units, 70 mm installation depth. Accepts solid or stranded conductors from 1.5 to 25 mm² at the screw terminals; tighten to 2.5–3 N·m. IP20 with conductors connected — standard for enclosed distribution boards. Finger and back-of-hand safe touch protection.
The 25 A rating holds at ambient up to 45 °C. Above that, derate linearly: 23.5 A at 50 °C, 22 A at 55 °C, 20.5 A at 60 °C, 19 A at 65 °C, and 17.5 A at 70 °C (–).
Fault ratings and coordination
Surge-current withstand is 3 kA, and the permissible I²t is 70 000 A²·s. Overvoltage category III suits fixed-installation distribution.