The Siemens 5SM1642-6FD is a Type A residual-current protective device (FI-Protector) in the PSE/SSF series, rated 25 A, 4-pole, with a rated residual current IΔn of 0.3 A at 400 V.
Deployment context
Snap-on DIN-rail mounting in a 4TE slot, with the 55 mm depth clearing most domestic and light-commercial enclosure depths. The 0.3 A IΔn is a common sensitivity for general socket-outlet protection in European installations (EN 60364-4-41).