What this MCCB carries in the carton
The Siemens SENTRON 3VA2340-5HN42-0AF0 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 and 121 kA at 415 V. The basic switch supplied is 3VA2340-5HN42-0AA0, and the integrated auxiliary trip is 3VA9608-0BB11. No holes in the box for the core protection function.
At 500 V the rating drops to 75.6 kA, and at 690 V to 17 kA — the interrupting curve follows system voltage. For a 400 A feeder on a 415 V supply with a high fault-current transformer, this breaker handles the full available fault without cascading to a main breaker.
Thermal derating — the real continuous current at panel ambient
At 55 °C it derates to 385 A, at 60 °C to 370 A, at 65 °C to 355 A, and at 70 °C to 340 A. For a panel running at 55 °C ambient — common in sealed enclosures with solar load — the breaker still carries 385 A, not the full 400 A. The maximum power loss is 96 W, which factors into enclosure thermal calculations.
Mounting dimensions and panel fit
Dimensions: 248 mm high, 184 mm wide, 110 mm deep. The 184 mm width is the 4-pole frame — standard for a 400 A MCCB in this class.
What this breaker does not include
The ETU350 release handles overcurrent protection only — line protection version. If the application requires remote tripping or ground fault, this is not the variant. The auxiliary contact set (1 NO/NC + 1 trip alarm) is present and wired to the HQ terminals.