The Siemens 5SM1617-6FD is a Type A residual-current protective device (FI-Protector) rated 80A, 2-pole, with a rated residual operating current IΔn of 0.3A at 230V. The 2.5TE (≈55mm) width fits standard DIN-rail distribution boards. Type A detection covers sinusoidal AC and pulsating DC residual currents — the common profile for single-phase rectifier loads, switched-mode power supplies, and inverter-fed equipment found in modern control panels.
The 80A rated current covers main incoming or sub-feed protection in panels up to that load — sized for a distribution board feeding multiple branch circuits. The 0.3A IΔn (300 mA) residual trip threshold is the standard for fire protection in commercial and industrial installations per IEC 60364; it provides earth-fault detection without nuisance tripping from normal leakage currents of connected equipment. Type A sensitivity ensures the device trips on pulsating DC faults from downstream electronics, which a standard Type AC device would not detect. The 2-pole (1P+N) form factor breaks the phase and neutral conductors, suitable for single-phase 230V circuits. The 2.5TE (module width) occupies 2.5 standard 18mm DIN-rail slots — plan panel fill accordingly when laying out a multi-way distribution board.