The Siemens 3VA1120-4GE42-0AA0-ZD00 is a 3VA1 IEC frame 160 molded-case circuit breaker in breaking capacity class S, rated 20 A with a 36 kA interrupting capacity at 415 V. It is a 4-pole unit with TM220 thermal-magnetic overload protection, adjustable Ir from 14 A to 20 A, and fixed short-circuit pickup Ii at 16 x In. The ATFM designation indicates line protection with N-conductor protection at 100%.
This breaker mounts in a standard panel or enclosure on a DIN rail or screw-fixed baseplate, depending on the 3VA1 accessories used. The 4-pole configuration with 100% N-conductor protection suits it for three-phase systems where neutral continuity is critical — typically 400 V distribution panels feeding mixed single-phase and three-phase loads.
The nut keeper kit for DC Power OEM in China is a factory-fitted option on this order code, indicating it was configured for an OEM application requiring captive hardware for DC-side terminations. This does not affect the breaker's AC ratings.