The 5SM3746-4BG: The 63 A continuous rating matches the feeder or main switch in a distribution board feeding a mixed load. The 500 mA trip threshold is higher than a standard 30 mA RCCB — it's chosen where nuisance tripping from leakage in long cable runs or VFD-fed motors would take a 30 mA unit out. Type B detection covers DC ripple up to 6 mA smooth DC and frequencies up to 1 kHz, which is what you get from variable-frequency drives, UPS systems, and EV chargers. The short-time delay (typically 40–150 ms) gives selectivity with downstream 30 mA RCDs: a fault on a socket circuit clears without dropping the main board.
The 4-pole form factor (3 phases + neutral) makes it the right choice for a three-phase supply with neutral. The 500 mA threshold is common for fire-protection RCDs in commercial installations — the building code often demands a 300 mA or 500 mA residual current device on the main switch to protect against arcing faults without tripping on normal leakage.