The 121 kA interrupting capacity at 240 V means it can safely clear a bolted fault on a high-capacity transformer secondary — think a 300 kVA 208Y/120 V transformer — without the arc flash escalating upstream.
This MCCB delivers 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V.
Above that it begins to taper: 62 A at 55 °C, 61 A at 60 °C, 60 A at 65 °C, and 58 A at 70 °C (–). If the panel ambient runs at 55 °C, you lose 1 A; at 70 °C you lose 5 A. For a 60 A continuous load in a hot enclosure, this breaker still holds — but you are at the edge of the curve.
Undervoltage release and auxiliary options
The UVR is a separate auxiliary release, not the main trip unit. The trip indicator is absent, so you will not get a visual flag on the front; you rely on the handle position.
The 76.2 mm width (3 inches) is standard for a 3-pole 63 A frame; it occupies three 25 mm module spaces on a DIN rail or a panel-mount cutout. The supplied basic switch order code is 3VA11634EF320AA0 — that is the internal switching mechanism; you order the full breaker as 3VA1163-4EF32-0CA0.