The Siemens 3VA1450-7EF42-0AA0 is a SENTRON molded case circuit breaker (MCCB) for line protection, rated 500 A at 40 °C with a 4-pole configuration and a TM240 thermal-magnetic overcurrent release. That 500 A continuous rating at 40 °C means it carries full load in a typical 40 °C panel environment without derating; above that, the thermal curve steps down to 452 A at 70 °C, which is the maximum operating temperature. The 440 kA breaking capacity at 240 V gives substantial fault-current headroom for high-available-fault installations, dropping to 242 kA at 415 V and 17 kA at 690 V.
Dimensions & Panel Fit
Power dissipation is 122.7 W maximum, so account for that heat load in the enclosure thermal calculation.
The TM240 release is a thermal-magnetic trip unit — thermal for overload protection, magnetic for short-circuit. The 4-pole design handles three-phase plus neutral switching, common for North American and European distribution panels.