What this MCCB is and what it does
The Siemens 3VA2340-7HL32-0AD0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current (Iu) in a 3-pole configuration, fitted with an ETU320 electronic trip unit for line protection. It is designed for main or feeder protection in distribution panels where high interrupting capacity is required — 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 52.5 kA at 690 V — giving it a very high SCCR for fault duty up to those levels without cascading upstream. The 800 V rated insulation voltage (Ui) suits it for 480 V and 600 V class systems with margin.
Thermal derating and panel integration
The breaker carries its full 400 A rating from 40 °C up to 50 °C ambient; above that it derates linearly to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. For a panel with a 50 °C internal ambient, no derating is needed. The 138 mm width, 248 mm height, and 110 mm depth fit standard SENTRON 3VA switchboard mounting footprints — verify gland-plate cutout against the existing panel layout. Maximum power loss is 96 W, which should be factored into enclosure thermal calculations.
Key features for the specifier
The ETU320 electronic trip unit provides adjustable overload and short-circuit protection curves. The breaker includes three auxiliary switches (HQ type) for status feedback to a PLC or annunciator panel. It has no undervoltage release, no voltage trigger, no phase-failure detection, no ground-fault monitoring, and no communication function — it is a straightforward line-protection device without add-on modules. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Mechanical endurance is rated at 15,000 operations.