The Siemens 5SV3446-6LA is a 4-pole residual current circuit breaker (RCCB) from the SENTRON family, rated 63 A at 50 Hz with a 100 mA Type A trip characteristic. That 100 mA sensitivity means it catches sinusoidal AC fault currents and pulsating DC fault currents — the kind you get from rectified loads like VFDs, switching power supplies, or single-phase drives. The instantaneous trip (no time delay) clears fast, but it also means you won't use it downstream of a delayed RCCB without a selectivity study.
Snaps onto standard DIN rail (REG). You can feed it from top or bottom — no orientation restriction. OVC III (overvoltage category III) means it's rated for the fixed-installation side of the meter, not downstream equipment. Silicon-free construction, so no outgassing worries in sealed enclosures near sensitive contacts.
Thermal derating you need to know
This RCCB holds its full 63 A rating from 40 °C up through 60 °C. At 65 °C it derates to 57.35 A; at 70 °C it drops to 48.8 A. The storage range is wider: -40 °C to 75 °C, but that's for shelf or transit, not running. Operating ambient is -25 °C to 45 °C.