The Siemens 3VA1120-3GD42-0AA0-ZD00 is a 4-pole circuit breaker from the 3VA1 IEC frame 160 series, rated at 20 A with a breaking capacity class N of 25 kA at 415 V. It uses a TM210 thermal-magnetic trip unit with fixed overload protection (Ir = 20 A) and fixed short-circuit protection set at 16 x In. The FTFM (Fixed Thermal Fixed Magnetic) design means no field-adjustable trip settings — what you see on the nameplate is what you get, which simplifies coordination studies but locks in the protection curve. The N conductor is protected at 100%, and it ships with a nut keeper kit specified for DC Power OEM builds in China.
What the Ratings Mean for Fit
The 25 kA Icu at 415 V puts this in breaking capacity class N — adequate for most commercial and light industrial distribution boards where the prospective short-circuit current stays under that threshold. The fixed Ir = 20 A and Ii = 16 x In (320 A magnetic pickup) make it a drop-in replacement for a line needing a non-adjustable 20 A feeder breaker. The 4-pole configuration with 100% N protection is typical for 3-phase + neutral systems where the neutral is not oversized; if your design expects a reduced neutral (50% or 0%), this breaker will trip on neutral overloads that a reduced-neutral breaker would ignore.
Integration Note
Mounts on standard DIN rail in the enclosure. The nut keeper kit is a mechanical aid for panel builders terminating DC Power OEM assemblies — it retains the terminal nuts during wiring, saving time on repetitive builds. The 3VA1 frame is the compact IEC variant; verify that the panel cutout and busbar spacing match the 160 A frame footprint, not the larger 250 A frame.