At 415/440 V the interrupting rating is still 121 kA, dropping to 75.6 kA at 500 V and 17 kA at 690 V, so the voltage class of your distribution determines which figure governs your coordination study. The motor-protection designation means the ETU350M includes phase-failure detection, so a lost phase on a motor feeder trips the breaker rather than letting the motor single-phase and burn. The trip indicator on the front gives a clear visual when the breaker has opened on fault — no guessing whether it was a manual off or a trip event.
Thermal derating and the real-world current limit
At 55 °C it derates to 96 A, at 60 °C to 94 A, and at 65 °C to 92 A, with a floor of 90 A at 70 °C. The maximum power loss is 75 W, which factors into the enclosure thermal calculation.
Auxiliary contacts and wiring
That gives you two form-C contacts for status feedback (open/closed) and a separate alarm contact that changes state only on a trip event — not on manual switching. The auxiliary release slot is empty (no shunt or undervoltage release fitted), so if you need remote tripping, that has to be added as a field-installable accessory.