Siemens SENTRON 3VA2340-5HN42-0KH0 — 400 A MCCB for Line Protection
The Siemens SENTRON 3VA2340-5HN42-0KH0 is a 4-pole molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, designed for line protection in industrial power distribution panels. Its interrupting capacity reaches 187 kA at 240 V AC and 121 kA at 415 V AC, which means it can safely clear high-fault currents in low-voltage switchgear without upstream coordination issues. This MCCB carries a shunt trip release (STL) and is equipped with 2 auxiliary switches plus 1 trip alarm switch (HQ), giving the control system full status feedback on breaker position and fault events.
Breaking Capacity and Thermal Derating
At 500 V the interrupting rating is 75.6 kA; at 690 V it drops to 7.5 kA — a steep derating curve that matters when the breaker is applied in 690 V wind or marine systems. The continuous current holds at 400 A from 40 °C 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. Panel builders should account for the enclosure's internal temperature rise when sizing the breaker. Maximum power loss is 96 W — a figure that drives ventilation requirements in sealed enclosures.
Physical Fit and Mounting
Dimensions are 248 mm height, 184 mm width, and 110 mm depth. The 110 mm depth is the critical dimension for shallow backpanels or gland-plate clearance — confirm the enclosure depth before cutting the mounting plate. The breaker mounts via a fixed (non-plug-in) base; no DIN-rail adapter is listed. Panel layout must allow front-access wiring for the 4-pole line and load terminals.