What this MCCB is and what it does
The Siemens 3VA2440-7JQ32-0BL0 is a SENTRON molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a continuous rated current of 400 A across the full ambient temperature range from 40 °C to 70 °C, meaning no derating is needed for elevated temperatures inside a crowded enclosure — a practical advantage when the panel runs warm. The 3-pole construction handles three-phase systems; the interrupting ratings climb to 330 kA at 240 V AC and hold at 242 kA through 440 V, then drop to 187 kA at 500 V and 9 kA at 690 V. That 330 kA figure at 240 V is the headline number for high-fault applications like service-entrance or large industrial switchboards where available fault current is substantial.
Key features for panel integration
The breaker includes an undervoltage release (UVR) for coordinated shutdown on loss of control voltage, and a communication function for integration with higher-level monitoring systems. The auxiliary switch complement is 2 auxiliary switches + 1 trip alarm switch + 1 electrical alarm switch HQ — enough to signal position and fault status back to a PLC or building management system without adding external interface relays. Physical footprint is 248 mm high, 138 mm wide, 110 mm deep; verify the mounting pattern against the existing panel cutout, but the 3VA family shares a common bolt-hole layout across the frame sizes, so a panel specified around a smaller 3VA2116 frame will accept this 400 A unit without re-drilling.
Selectivity and coordination
The instantaneous trip setting starts at 600 A (minimum) and goes to 6 000 A (maximum), with a short-time withstand of 5 kA limited to 1 second. The full-scale current rating is 400 A, and the initial value for the long-time pickup is 80 A. This range allows selective coordination with downstream breakers — the 3VA2440 can be set to ride through motor starting inrush or transformer energization while still clearing a hard fault upstream. The trip indicator confirms the breaker has opened on a fault, which saves troubleshooting time on a multi-feeder panel.
Environmental and compliance
Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Maximum power loss is 66 W, which factors into enclosure thermal calculations if the panel is tightly packed. The design is line-protection (not motor-protection), so it is suited for feeder and main breaker duty rather than individual motor branch circuits.