MCCB for 400 A feeder protection
The Siemens SENTRON 3VA2440-6HL32-0BL0 is a 3-pole molded case circuit breaker rated for 400 A continuous current (Iu) with an ETU320 electronic trip unit. Its interrupting capacity reaches 242 kA at 240 V AC, 187 kA at 415/440 V, and 121 kA at 500 V — figures that govern its placement in high-fault panels where selective coordination with downstream breakers is required. The 800 V rated insulation voltage (Ui) sets the maximum system voltage the breaker can be applied to, per IEC 60947-2.
Thermal derating and operating envelope
The breaker holds its full 400 A rating up to 50 °C ambient. Above that, derate linearly: 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. Maximum operating temperature is 70 °C; storage range spans -40 °C to 80 °C. The 66 W maximum power loss at rated current matters for enclosure thermal calculations — factor it into the panel cooling budget.
Auxiliary and release configuration
This variant ships with an undervoltage release (UVR) — design of the auxiliary release is undervoltage release. The auxiliary contact block includes 2 auxiliary switches, 1 trip alarm switch, and 1 electrical alarm switch HQ. The integrated auxiliary trip is order code 3VA9608-0BB11. A trip indicator is present. Latching endurance is rated at 15,000 operations.