What this MCCB carries and where it fits
The Siemens 3VA2340-5JQ32-0BA0 is a 3-pole SENTRON molded case circuit breaker rated 400 A continuous at 40 °C ambient, designed for line protection in distribution panels. Breaking capacity reaches 187 kA at 240 V and 121 kA at 415 V — enough to handle high-fault utility feeds or transformer secondaries without cascading upstream. The frame holds the same interrupting rating across the 400 A continuous band, so you don't lose headroom as load approaches the trip setting. An integrated undervoltage release (UVR) is factory-fitted — when control voltage drops below the dropout threshold, the breaker trips open. That makes this variant suited for applications where loss of control power must automatically disconnect the load (e.g., emergency-stop chains or undervoltage protection on motor feeders). No auxiliary switch is included on this order code; if you need remote status feedback, you'll add a separate auxiliary switch module.
Thermal derating — the real current you get
The 400 A rating holds flat up to 50 °C. Above that, the frame derates in 25 A steps: 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. If your panel ambient runs above 50 °C, size the breaker for the derated value — the trip unit is thermal-magnetic and responds to actual heat, not the nameplate. At 98.5 W maximum power loss, ventilation in the enclosure matters; tight gutters with no airflow will push internal temperature past the 50 °C threshold.
Dimensions and panel fit
Footprint: 248 mm high, 138 mm wide, 110 mm deep. That's a standard 3-pole MCCB frame for 400 A class — fits most DIN-rail or panel-mount enclosures with a 3-pole cutout. The 110 mm depth leaves room for rear-connected busbars or cable lugs without forcing a deeper enclosure than necessary.