The Siemens SENTRON 5SV3324-4 is a Type B residual current circuit breaker (RCCB) rated for 40 A at 50/60 Hz, with a 30 mA trip threshold and a 10 kA short-circuit current rating. Its short-time delayed design (SIGRES function) allows selectivity with upstream devices, so a downstream fault clears without dropping the main feeder — useful in distribution panels where you want to isolate a branch, not the whole board.
Type B detection covers AC, pulsating DC, smooth DC, and high-frequency residual currents up to 1 kHz — that means it catches variable-speed drive leakage and UPS harmonics, not just line-frequency faults. The 30 mA trip is the standard for personnel protection (IEC 61008-1), so this unit doubles as both equipment and shock-hazard protection in the same enclosure. Supply can enter top or bottom; for the SIGRES function, keep the supply at the top so the test circuit remains powered even when the RCCB is switched off.