The Siemens 3VA1450-5GE42-0AA0-ZD00 is a 4-pole molded case circuit breaker in the 3VA1 IEC frame 630 series, rated for line protection with a TM220 thermal-magnetic trip unit and ATFM (adjustable thermal, fixed magnetic) characteristics. The continuous current rating In=500 A, with overload protection adjustable from 350 A to 500 A via the Ir dial, and short-circuit protection fixed at Ii=10 x In (5000 A). The N conductor is protected at 100%, so this breaker handles full-phase imbalance on a 4-wire system without derating the neutral.
The 4-pole configuration with 100% neutral protection makes it a direct fit for three-phase plus neutral distribution in industrial MCCs, UPS bypass panels, or generator paralleling gear. The nut keeper kit included (ZD00 suffix) is a factory-fit accessory for DC Power OEM applications in China — it retains the terminal nuts during vibration, so you don't lose torque on a shipping container or genset skid. Verify the terminal spread matches your busbar pitch before committing the BOM.