The Siemens 3VA1340-4EF42-0BB0 is a 4-pole SENTRON molded case circuit breaker (MCCB) rated for 400 A at 40 °C, with a breaking capacity of 121 kA at 240 V and 75.6 kA at 415 V — numbers that tell you this breaker handles heavy fault currents without cascading upstream.
At 240 V the interrupting rating hits 121 kA — that's enough for high-fault locations like a turbine pad-mount transformer secondary or a large motor control center bus. The rating drops to 75.6 kA at 415 V and 52.5 kA at 500 V, and to 11.9 kA at 690 V, so match the available fault current at the installation point. The continuous current holds at 400 A through 50 °C, then derates to 392 A at 55 °C and 376 A at 70 °C — a gentle slope that buys you margin in a warm enclosure.
The 3VA1340-4EF42-0BB0 measures 248 mm high by 184 mm wide by 110 mm deep — a 4-pole frame that fits standard Siemens SENTRON mounting patterns.