The Siemens 5SM2633-6 is a SENTRON residual-current device (RCD) designed for 3-pole AC circuits at 50 Hz, rated 40 A with a 300 mA Type A tripping characteristic. It's an instantaneous unit — no adjustable time delay — so it trips as soon as the residual current exceeds threshold. That 300 mA rating makes it suitable for equipment protection rather than personnel shock protection (which typically calls for 30 mA). The Type A designation means it detects pulsating DC fault currents on top of sinusoidal AC, covering rectifier-fed loads like VFDs, switching power supplies, and LED drivers.
The 40 A rating holds at 40 °C ambient (37.2 A at both 40 °C and 45 °C). From there it steps down: 36 A at 50 °C, 34.8 A at 55 °C, 34 A at 60 °C, 33.2 A at 65 °C, and 32 A at 70 °C.
Fastening method is standard REG (regular) snap-on; mounting position is any orientation. The IP20 rating applies only when the distribution board is installed with conductors connected — it's a panel-internal device, not a standalone outdoor unit. Not sealable.