The Siemens SENTRON 5SV3644-6KL is a 4-pole residual current circuit breaker (RCCB) rated 40 A at 230/400 V AC, 50 Hz, with a 300 mA residual trip threshold and Type A waveform sensitivity. It is an instantaneous design — no intentional short-time delay — so it trips as soon as the fault current exceeds the threshold.
The 40 A rating holds at 40 °C ambient; derate to 38.1 A at 45 °C, 35.59 A at 50 °C, and drops sharply above that — 17.6 A at 70 °C. If your panel runs hot, size the upstream breaker accordingly. The 300 mA residual threshold suits circuits with high leakage from electronics or long cable runs, where a 30 mA device would nuisance-trip. Type A detects pulsating DC fault currents (common from rectifier loads) in addition to sinusoidal AC. The instantaneous trip means no coordination delay — the RCCB opens fast on a ground fault.
Mounts on DIN rail (REG) in any orientation. Width is 72 mm (4 modular units). Depth 70 mm. The N terminal is on the left side of the device. Rated for overvoltage category III. IP20 with conductors connected — fine inside a closed distribution board.