What it is and what it does
The Siemens SENTRON 3VA2340-7HL32-0BA0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in distribution panels. It carries a maximum interrupting capacity of 330 kA at 240 V, dropping to 242 kA at 415 V and 440 V, 187 kA at 500 V, and 7.5 kA at 690 V — so at typical 400 V-class industrial feeds it handles fault currents up to 242 kA without upstream coordination issues. The breaker includes an undervoltage release (UVR) that trips the mechanism when supply voltage drops below a set threshold, which is a common requirement for motor control centers and safety circuits that need to drop out on loss of control power.
Thermal derating and panel fit
The 400 A rating holds flat from 40 °C through 50 °C, then derates to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. In a sealed enclosure or high-ambient machine cabinet, that means you lose 60 A by the time the internal air hits 70 °C — plan the load accordingly or add ventilation. Dimensions are 248 mm high × 138 mm wide × 110 mm deep, which fits the standard SENTRON 3VA mounting footprint; the panel cutout and bus-bar spacing match the existing 3VA line. Maximum power loss at rated current is 98.5 W, so the breaker itself dumps about 100 W into the enclosure — factor that into your thermal budget if you're stacking multiple units.