The Siemens SENTRON 3VA2340-5HL42-0CA0 is a 4-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with an interrupting capacity of 187 kA at 240 V AC and 121 kA at 415/440 V. The continuous rating holds flat at 400 A up to 50 °C, then derates to 385 A at 55 °C and 340 A at 70 °C, so you don't lose headroom unless the cabinet runs hot.
At 240 V it's rated 187 kA, at 415 V and 440 V it's 121 kA, at 500 V it drops to 75.6 kA, and at 690 V it's 7.5 kA. That steep roll-off above 500 V means this breaker is optimized for 400/480 V distribution — not for 690 V motor circuits. The minimum breaking capacity is 600 A, so it's not for tiny branch circuits.
That 184 mm width is a 4-pole frame — it needs a 4-module-wide cutout in a panel or a dedicated MCCB mounting base.