The 5SM3644-8LA: The 300 mA rated residual current and selective (time-delayed) design mean this RCCB is intended for the upstream or main-switch position in a distribution board, where it coordinates with downstream 30 mA RCCBs. Type A detection covers sinusoidal AC and pulsed DC fault currents up to 6 mA smooth DC superimposed — the standard for modern electronics and variable-speed drives on the load side. Overvoltage category III confirms suitability for fixed-installation distribution panels, not just socket-outlet circuits.
Snap-on DIN rail (REG) mounting, 4 width units (roughly 72 mm at 18 mm/module), installation depth 70 mm. Mounting position any, supply connection top or bottom. IP20 with connected conductors in an enclosed distribution board — standard for panel interior, not for wet or outdoor locations.