The Siemens 3VA1125-4GF42-0AA0-ZD00 is a 4-pole IEC frame 160 circuit breaker in breaking capacity class S, rated Icu=36kA at 415V. It carries a TM240 thermal-magnetic trip unit with ATAM (adjustable thermal, adjustable magnetic) — overload protection Ir adjustable from 18A to 25A, short-circuit protection Ii adjustable from 6.4 to 12.8 times In. The N conductor is protected at 100%.
What the ratings mean for fit
The 36kA breaking capacity at 415V means this breaker can safely interrupt fault currents up to that level without upstream devices needing to clear first — critical for selectivity coordination in a distribution panel. The TM240 trip unit gives you field-adjustable overload (Ir) and short-circuit (Ii) settings, so you tune the protection to the actual load cable and motor inrush without swapping the breaker. The 100% N protection means the neutral pole is fully rated and trips with the phases, not derated or omitted — required for systems with significant harmonic or unbalanced loads.
Deployment context
Mounts on a standard DIN rail in a panel enclosure. The 4-pole format suits three-phase four-wire systems (e.g. TN-S or TN-C-S) where neutral protection is mandatory. The nut keeper kit included suggests an OEM application in China where DC power distribution is common — verify the DC rating if using on a DC bus.