400 A continuous, flat derating curve to 70 °C
The Siemens SENTRON 3VA2440-5HN32-0BJ0 is a 3-pole molded case circuit breaker rated 400 A continuous across the entire 40 °C to 70 °C operating range — no derating needed until you exceed 70 °C ambient. That flat thermal curve simplifies panel design in warm enclosures where adjacent devices raise the internal temperature. Breaking capacity scales with system voltage: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 9 kA at 690 V. The 9 kA figure at 690 V is the limiting case for high-voltage industrial networks; the 187 kA at 240 V covers most North American low-voltage fault scenarios with margin. Designed for line protection, this MCCB includes an undervoltage release and a factory-fitted auxiliary switch configuration: 2 auxiliary switches plus 1 trip alarm switch. The auxiliary contacts allow remote status monitoring of breaker position and trip events — useful for feeding a PLC digital input or a panel HMI for fault annunciation.
Physical fit and panel integration
Envelope dimensions: 138 mm wide, 248 mm tall, 110 mm deep. The 138 mm width is the critical dimension for DIN-rail or mounting-plate layout — it occupies three adjacent 45 mm module spaces in a standard distribution panel. Depth of 110 mm includes the breaker body plus the rotary handle projection; verify gland-plate clearance if the breaker is mounted near the enclosure door. Maximum power loss is 66 W — factor that into enclosure thermal calculations, especially in sealed cabinets without forced ventilation.