What this breaker is and what the ratings mean for fit
The Siemens 3VA1120-4EF42-0AA0-ZD00 is a 4-pole IEC frame 160 circuit breaker from the 3VA1 series, configured for line protection with a TM240 thermal-magnetic trip unit. The 36 kA breaking capacity at 415 V (class S) means it can safely interrupt fault currents up to that level without upstream cascading — a key figure for panel SCCR coordination. The TM240 trip provides adjustable overload protection (Ir = 14 A to 20 A) and fixed short-circuit protection (Ii = 8 to 16 × In), so the 20 A In rating lets you dial the thermal pickup to match the actual load current on the BOM.
Deployment context
Mounts in a standard IEC panel on DIN rail or via the frame's bolt-on footprint. The 4-pole configuration with unprotected N conductor suits 3-phase + neutral systems where the neutral does not require overcurrent protection — common in distribution sub-feed panels. The nut keeper kit is included for DC Power OEM builds in China, so verify the termination hardware matches your panel's bus-bar or cable lug pattern.