The Siemens 5SM1617-6BA is an 80 A, 2-pole residual-current device (RCD) of Type A, with a rated residual operating current (IΔn) of 0.3 A. It is designed for 230 V AC circuits and occupies 2.5 TE (module-width units) on a DIN rail. The "FI PROTECTOR>N<" designation indicates it is a compact, non-switched RCD block, and the Type A classification means it detects pulsating DC residual currents as well as sinusoidal AC — the standard requirement for circuits with single-phase rectifiers, switched-mode power supplies, or frequency converters.
What the ratings mean for fit
The 80 A rated current sets the thermal capacity for the main circuit — sized for a 3-phase (or single-phase) feeder up to that load, not for motor starting duty. The 0.3 A IΔn is the trip threshold for earth leakage; it is higher than the common 30 mA (0.03 A) used for personal protection and is typically chosen for circuits where a higher standing leakage is expected (e.g., long cable runs, industrial equipment with EMC filters). Type A selectivity (PSE/SSF in the description) means this device is coordinated to discriminate with downstream RCDs — a fault on a subcircuit trips the downstream device, not this main RCD, keeping the rest of the panel live.