What this breaker is and what the ratings mean for your panel
The Siemens 3VA1120-4GF42-0AA0-ZD00 is a 4-pole IEC frame 160 molded case circuit breaker from the 3VA1 series, configured for line protection with a TM240 thermal-magnetic trip unit. The 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 governs the available fault current your panel's bus can tolerate upstream. Rated In is 20 A, with overload protection adjustable from Ir=14 A to 20 A via the ATAM dial, and short-circuit protection fixed at Ii=8 to 16 times In (160 to 320 A). The N conductor is protected at 100% (full-rated), and the unit includes a nut keeper kit specified for DC Power OEM builds in China.
Deployment context
As a 4-pole IEC frame 160 MCCB, this breaker mounts into a panelboard or enclosure on a DIN rail or direct-mount base. The 36 kA interrupting rating at 415 V makes it suitable for main or branch feeder protection in industrial and commercial distribution boards where the available fault current is known to be within that limit. The nut keeper kit indicates it is prepared for DC Power OEM integration, likely in a pre-wired assembly.