The Siemens 3VA2580-5HN32-0DB0 is a 3-pole IEC frame 1000 circuit breaker rated 800 A with an ETU350 LSI trip unit. The overload protection is adjustable Ir=320 A...800 A, short-circuit protection Isd=1.5...10 x Ir, and the instantaneous pickup Ii=12 x In.
The ETU350 is an electronic trip unit with LSI curves: Long-time (overload), Short-time (selective coordination), and Instantaneous (magnetic-only). The adjustable Ir from 320 A to 800 A lets you match the breaker to the actual load current, not just the frame size. The Isd short-time pickup range of 1.5 to 10 x Ir gives selectivity headroom downstream — critical for a distribution panel feeding multiple sub-feeders. The undervoltage release (208-230 V AC) is wired in series with the emergency-stop chain; when control voltage drops, the breaker trips, removing power from the load. This is a common requirement for machine safety circuits per IEC 60204-1.