The Siemens 3VA1112-4EF32-0AA0-ZD00 is a 3-pole IEC frame 160 molded case circuit breaker with a 125 A nominal rating and a 36 kA interrupting capacity at 415 V (breaking capacity class S). That Icu figure means it can safely clear a fault up to 36,000 A at 415 V without welding its contacts or rupturing the case — a key spec for panel builders sizing the upstream fault current. The TM240 thermal-magnetic trip unit gives adjustable overload protection from 88 A to 125 A (Ir), and short-circuit pickup (Ii) is fixed at 5 to 10 times In.
What the ratings mean for fit
The 125 A In and 36 kA Icu @ 415 V place this breaker squarely in the 'S' (standard) breaking capacity class for the 3VA1 frame. For a 415 V line, that Icu covers most industrial distribution panels fed by a transformer of 1,000 kVA or less. The TM240 trip unit's adjustable Ir (88–125 A) lets you fine-tune the overload threshold to match the downstream cable or busway rating without swapping the breaker. The nut keeper kit is a line-item detail for the DC Power OEM variant destined for China — it secures the terminal nuts against vibration in transport or high-vibration environments like a data-center power skid.
Panel integration
Mounts on a standard DIN rail or can be screw-fixed to a backplate. The 3VA1 frame is a compact IEC design — 105 mm wide per pole — so a 3-pole unit fits a 315 mm-wide DIN section. Leave 50 mm clearance above and below for arc-chute venting and cable bending radius. The nut keeper kit is pre-installed; no additional hardware needed for the line and load terminals.