The Siemens 3VA1340-5EF42-0AA0-ZD00 is a 4-pole IEC frame 400 molded-case circuit breaker from the 3VA1 series, configured for line protection with a TM240 ATAM trip unit. The In=400 A continuous rating and adjustable overload protection (Ir = 280 A to 400 A) let you match the breaker to the cable or busbar ampacity, not the other way around.
The TM240 ATAM is a thermal-magnetic trip unit. The thermal element handles overloads (Ir adjustable 280–400 A), and the magnetic element handles short-circuits (Ii adjustable 5 to 10 x In, so 2000 A to 4000 A). The N conductor is unprotected on this variant, which is standard for 3-phase loads where the neutral carries only unbalanced current.