What this breaker is and what the ratings mean
The Siemens 3VA1120-4ED42-0AA0-ZD00 is a 4-pole IEC frame 160 circuit breaker from the 3VA1 series, built for line protection with a TM210 thermal-magnetic trip unit. Its breaking capacity is 36 kA at 415 V (class S), meaning it can safely interrupt a fault current up to that level without welding the contacts or cascading an arc upstream — critical for panel SCCR compliance. The fixed overload protection is set at Ir = 20 A, and the short-circuit pickup is fixed at Ii = 16 × In (320 A), so the magnetic trip reacts fast on a hard short but lets motor inrush through. This variant ships with a nut keeper kit and is designated for DC Power OEM builds in China.