What this 400 A MCCB is and what the ratings mean for your panel
The Siemens SENTRON 3VA2340-5HN32-0DL0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C. That 400 A is the full-load handle rating — it carries that current indefinitely in a 40 °C ambient without tripping. Above 55 °C you need to derate: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If your panel ambient runs hot, the 55 °C and 60 °C figures are the ones that decide whether this breaker fits the load. Breaking capacity is the other headline. At 240 V it interrupts 187 kA — that's high enough for most service-entrance and large feeder applications. At 415 V it's still 121 kA, and at 690 V it drops to 7.5 kA. The 690 V figure matters if you're on a 690 V IT or corner-grounded delta system; at that voltage the breaker is still rated for the 400 A frame but the fault clearing limit is much lower. This is a line-protection design, meaning the trip curve and thermal-magnetic or electronic trip unit are set for protecting cables and busbars, not motor overloads. It includes an undervoltage release and comes with a complement of auxiliary switches: 2 auxiliary switches + 1 trip alarm switch + 1 electrical alarm switch HQ. The basic switch supplied is 3VA2340-5HN32-0AA0.
Mounting dimensions and panel fit
The breaker measures 248 mm high × 138 mm wide × 110 mm deep. That 138 mm width is the standard 3-pole MCCB footprint for the SENTRON 3VA frame at this rating — it occupies the same DIN-rail or screw-mount pattern as other 3VA breakers in the same frame size. If you're swapping into an existing panel, check the gland-plate cutout and the busbar spacing against the 110 mm depth; the undervoltage release module adds a few mm behind the breaker body.