The 3VA1220-4GE42-0AA0-ZD00 is a 4-pole IEC frame 250 molded-case circuit breaker with a 36 kA interrupting capacity at 415 VAC — that's the Icu (ultimate breaking capacity) at the standard industrial distribution voltage, meaning it can safely clear a bolted fault up to that level without welding contacts or venting gas into the panel. The TM220 thermal-magnetic trip unit gives you adjustable overload protection from 140 A to 200 A (Ir) and a fixed short-circuit pickup at 10× In (Ii = 2000 A). That 10× multiplier is typical for line protection on motor feeders or transformer secondaries where you need to ride through inrush without nuisance tripping. The 100% N-conductor protection means the neutral pole is fully rated — not reduced — so it's suited for 3-phase + N distribution where harmonic currents or unbalanced loads could push the neutral.
Mounts in a standard IEC panel — frame 250 footprint, 4-pole width. The nut keeper kit (included per the ZD00 spec) holds the mounting hardware captive during panel assembly, a small time-saver on repetitive builds. The ATFM designation indicates the accessory trim and flange-mounted rotary handle configuration; verify handle protrusion against enclosure door depth before cutting the gland plate.