The K curve is designed for motor and transformer circuits where inrush currents are higher than resistive loads — it holds through the starting surge but trips fast on a hard short.
The 2-pole width occupies two modular spaces (36 mm) in the enclosure. Terminal clamps accept 1.5–25 mm² copper conductors. For panel builders: the K-curve coordination with downstream motor starters is straightforward — the magnetic trip threshold is 8–12× In, so a 63 A breaker will hold a 40 A motor start but clear a bolted fault ahead of the contactor.