The 4-pole configuration handles three-phase plus neutral protection, common for main incomers or feeder breakers in 400 V distribution panels. Breaking capacity is 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 7.5 kA at 690 V — the steep drop above 500 V means this breaker is sized for low-voltage main distribution, not 690 V motor circuits. The ETU350 is a programmable electronic trip unit with LSI (long-time, short-time, instantaneous) protection curves, adjustable via the front interface, so coordination studies can be dialed in without swapping trip packs.
Temperature derating — the real-world current
Above that, derate linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs at 55 °C, the breaker delivers 385 A continuous — not 400 A.
Dimensions: 248 mm height, 184 mm width, 110 mm depth. The 184 mm width is for a 4-pole frame — verify the panel cutout or mounting plate accommodates that before committing the BOM.