What it is and what it does
The Siemens SENTRON 3VA2340-8HN32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for line protection, carrying a continuous current of 400 A at 40–50 °C and an ETU350 electronic trip unit. Its breaking capacity reaches 440 kA at 240 V, 330 kA at 415 V, and 52.5 kA at 690 V — meaning it can safely clear high-fault currents in low-voltage distribution without upstream cascading.
Breaking capacity and thermal derating — what the numbers mean
At 240 V the 440 kA rating covers most North American transformer-fed services; at 415/440 V the 330 kA figure suits heavy industrial switchboards. The 52.5 kA at 690 V still exceeds typical European 690 V plant-floor fault levels. Thermal derating starts at 55 °C — the 400 A rating holds through 50 °C, then drops to 385 A at 55 °C, 370 A at 60 °C, and 340 A at 70 °C. Factor that into the panel ambient if the breaker sits near transformers or drives.
Panel fit and mounting
Dimensions are 248 mm high, 138 mm wide, 110 mm deep. The 138 mm width is standard for a 3-pole MCCB in this class — it fits a typical 3× 45 mm DIN cutout or direct screw-mount plate. IP40 on the front means the enclosure protects against tools and wires larger than 1 mm; the back and sides are open for panel ventilation. Max power loss is 96 W, so allow convection clearance.