The Siemens 5SY4405-7CV is a 4-pole miniature circuit breaker (MCB) rated for a 15 kA breaking capacity at 400 V AC, with a C-trip curve and 0.5 A current rating. The C-curve characteristic means it trips between 5 and 10 times rated current — suited for moderate inrush loads like small motors or transformer banks in distribution panels.
The 15 kA Icu (ultimate short-circuit breaking capacity) at 400 V tells you this breaker can safely interrupt faults up to that level without upstream damage — a key spec for panel SCCR coordination in industrial or commercial mains distribution.