The Siemens 3VA2125-7KQ32-0DG0 is a 3-pole IEC frame 160 molded-case circuit breaker with a 110 kA interrupting rating at 415 VAC — breaking capacity class C, which means it handles high-fault-current industrial feeds without cascading upstream. The ETU860 electronic trip unit provides full LSIG protection (long-time, short-time, instantaneous, ground fault), adjustable over a wide band: overload Ir from 10 A to 25 A, short-time pickup Isd from 0.6 to 10× In, instantaneous Ii from 1.5 to 12× In, and ground-fault pickup Ig from 0.2 to 1× In with time delay tg from 0.05 to 0.8 s.
What the ratings mean for fit
The 110 kA Icu at 415 V is the ultimate breaking capacity — the breaker can safely clear a fault at that level once without needing replacement. For most industrial distribution panels fed from a 1 MVA transformer, that's enough headroom to avoid series-rating tricks. The LSIG trip unit gives you selectivity coordination with downstream feeders: the adjustable short-time delay (0.05–0.8 s) lets a downstream breaker clear a bolted fault first, keeping this main breaker closed for service continuity. The undervoltage release (UVR) is rated 208–230 V AC, 50/60 Hz, wired to the control transformer. It drops the breaker on loss of control voltage — standard for motor control centers where you want automatic shutdown on undervoltage. The auxiliary switch and trip alarm switch (both rated for high-performance switching) provide status feedback to a PLC or annunciator panel.