What this 400 A MCCB is and what the ratings mean for fit
The Siemens 3VA2340-7HN32-0BA0 is a SENTRON 3VA2 molded case circuit breaker rated for 400 A continuous current at 40 °C, with a 3-pole configuration and line-protection design. It carries a 330 kA interrupting capacity at 240 VAC, 242 kA at 415/440 V, 187 kA at 500 V, and 7.5 kA at 690 V — meaning it can safely clear fault currents up to those levels without upstream cascading, sized for high-available-fault installations like transformer secondaries or large bus risers. The continuous current rating holds at 400 A through 50 °C ambient, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs above 50 °C, the breaker's effective capacity drops — size the load and enclosure ventilation accordingly. It includes an undervoltage release (UVR) as the auxiliary release, meaning the breaker trips when control voltage drops below a set threshold — typical for safety circuits or emergency-stop chains where loss of control power must open the main contacts. The auxiliary switch is not fitted, so no remote status indication from the breaker itself.
Physical fit and panel integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. This is a standard SENTRON 3VA2 frame size — mounts via screw-clamp or optional DIN-rail adapter. Check the existing panel's backplate layout against the 138 mm width and 110 mm depth, especially if replacing a different-frame MCCB where bus-bar centers or gland-plate clearance may differ.