Type A residual current detection handles pulsating DC faults, not just pure AC, so it covers electronics and rectifier-fed loads. 300 mA sensitivity is typical for fire protection or circuits where nuisance tripping from leakage must be avoided.
Panel integration
Snap-on mounting to DIN rail EN 60715. 4-module width (roughly 72 mm) occupies two standard 18 mm positions — factor this into enclosure fill calculations.