The Siemens 3VA2340-5HL32-0CH0 is a 3-pole SENTRON molded case circuit breaker rated for 400 A continuous current at 40 °C, with a maximum breaking capacity of 187 kA at 240 V AC. The 187 kA at 240 V covers high-fault service-entrance positions; at 415 V it still holds 121 kA, and at 690 V it derates to 7.5 kA — so the voltage class of your bus determines which interrupting rating governs the fit.
Above that it steps down: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. The unit measures 248 mm high by 138 mm wide by 110 mm deep, which fits standard MCCB mounting footprints in Siemens SENTRON distribution boards. Max power loss is 98.5 W at rated load, so account for that heat in the enclosure ventilation calculation.