The 63 A rating holds flat from 40 °C up to 50 °C ambient; above that it derates to 60.6 A at 55 °C and 53.6 A at 70 °C, so if your enclosure runs hot, size the breaker for the actual ambient, not the nameplate. Interrupting capacity is the headline number here: 242 kA at 240 V AC, 187 kA at 415/440 V, 121 kA at 500 V, and 5 kA at 690 V. The ETU350 is a basic electronic trip unit — no ground-fault monitoring, no phase-failure detection, no communication. It handles LSI protection (long-time, short-time, instantaneous) with adjustable pickup and delay settings via DIP switches on the front face. The 4 auxiliary switches (HQ version) give you status feedback for remote monitoring or PLC inputs.
Dimensions are 105 mm wide, 181 mm high, 86 mm deep — a standard 3-pole MCCB footprint for the SENTRON 3VA2 frame. Terminal layout accepts copper or aluminum conductors up to the rated cross-section; the 4 auxiliary switches add about 18 mm to the width compared to a bare breaker.
Thermal and environmental limits
Maximum power loss is 4 W at rated current — negligible for panel cooling calculations. If you're cycling this breaker daily as a disconnect, that's fine; if you're switching it hourly, consider a contactor upstream.