What this MCCB brings to a motor branch
Thermal derating — the real ampacity
Rated continuous current Iu is 250 A, but that's at 40 °C ambient. The derating curve is flat up to 50 °C (still 250 A), then drops to 240 A at 55 °C, 235 A at 60 °C, 230 A at 65 °C, and 225 A at 70 °C.
Breaking capacity across voltage classes
This MCCB's interrupting rating varies sharply with system voltage: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 52.5 kA at 690 V. That 52.5 kA at 690 V is still well above the typical 25–50 kA available fault current on a 690 V industrial bus, so selectivity coordination with downstream breakers is straightforward.
That 138 mm width is the standard 3-pole MCCB envelope for the 3VA2 frame — it occupies the same DIN-rail or screw-mount positions as the 3VA1 and 3VA2 siblings.