What this breaker is and what the ratings mean
The Siemens 3VA1120-4ED32-0AA0-ZD00 is a 3VA1 IEC frame 160 molded-case circuit breaker (MCCB) with a 3-pole configuration, rated for line protection. Its breaking capacity class S delivers an Icu of 36 kA at 415 V AC — that is the maximum fault current it can safely interrupt without damage, which covers most industrial distribution panels fed by a transformer in that voltage class. The thermal-magnetic trip unit is fixed: overload protection Ir is set at 20 A (non-adjustable), and the short-circuit protection Ii is fixed at 16 x In (320 A instantaneous pickup). This is a line-protection (TM210) device, meaning it is designed for cable and busbar protection, not motor starting — the magnetic pickup is too high for a motor inrush profile.
Deployment context
This MCCB mounts on a DIN rail or panel-mount base inside a standard industrial enclosure. The nut keeper kit (included per the order-code suffix) is intended for DC Power OEM builds in China — it retains the terminal nuts during vibration or transport, a detail that matters if the breaker ships as part of a pre-wired assembly rather than a loose spare.