The Z-curve means it trips between 2.5 and 4 times rated current — designed for semiconductor or sensitive electronic load protection where standard B or C curves would nuisance-trip on inrush. This is the part to specify when protecting power supplies, rectifiers, or control transformers that draw a low, steady current.
The S800 series uses a modular 17.5 mm per-pole width, so this single-pole unit occupies one module space. Wire termination accepts copper conductors up to 35 mm² — sized for the full 15 A rating without derating on the terminals.