What the ratings mean for a 400 A line-protection MCCB
The Siemens 3VA2340-5KP32-0AJ0 is a SENTRON molded case circuit breaker (MCCB) sized for 400 A continuous duty, with an adjustable thermal-magnetic trip unit covering 600 A to 4000 A — so it protects feeders and large motor circuits where the full-load current lands in that band. The interrupting ratings climb to 187 kA at 240 V AC, drop to 121 kA at 415 V and 440 V, then 75.6 kA at 500 V, and 7.5 kA at 690 V. That SCCR curve tells you where it can sit without cascading upstream: at 480 V (common in North American plants) it holds 121 kA; at 690 V (European industrial grids) the 7.5 kA limit means you need a current-limiting upstream device if fault current exceeds that. Continuous current is rated 400 A from 40 °C through 50 °C, then derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C — so a panel builder stuffing this into a warm enclosure needs to check the ambient derating curve before committing the BOM line. It ships with the basic switch 3VA2340-5KP32-0AA0 and includes 2 auxiliary switches plus 1 trip alarm switch (HP type) — enough for remote status indication without adding an external aux block. The communication function is onboard, so it can feed power-monitoring data to a higher-level system. No undervoltage release or ground-fault monitoring is fitted; those are add-on options if the application requires them.
Integration and panel fit
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That depth (110 mm) is shallow enough for most standard distribution panels; the 138 mm width means it occupies three pole spaces on a DIN-rail or panel-mount footprint. Maximum power loss is 96 W — factor that into enclosure thermal calculations, especially if the panel is sealed or has limited ventilation.