What this 400 A MCCB delivers
The Siemens SENTRON 3VA2340-5HL42-0JC0 is a 4-pole molded case circuit breaker rated for 400 A continuous current at 40 °C through 50 °C without derating — it holds full rating across the typical switchroom ambient band. At 55 °C it still delivers 385 A, at 60 °C it gives 370 A, and at 70 °C it provides 340 A, so you can place it in a warmer enclosure or near other heat sources and still get useful capacity. Breaking capacity reaches 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 7.5 kA at 690 V — the 415 V figure is the one that governs for most 400 V-class industrial distribution, and 121 kA covers nearly any fault level you will see downstream of a utility transformer. This is a line-protection design (not a motor-protector or feeder switch), so its trip curve and thermal-magnetic or electronic characteristics are tuned for cable and busbar protection.
The breaker measures 184 mm wide, 248 mm tall, and 110 mm deep.