What this MCCB is and what it does
The Siemens SENTRON 3VA2340-7HN32-0DA0 is a 3-pole molded case circuit breaker (MCCB) rated for 400 A continuous current, designed for line protection in distribution panels and switchgear. It carries a 330 kA interrupting capacity at 240 VAC, 242 kA at 415/440 V, 187 kA at 500 V, and 7.5 kA at 690 V — so the same breaker can be specified across multiple voltage levels without swapping frames, as long as the available fault current stays under the curve at the service voltage.
Thermal performance and derating
The breaker holds its full 400 A rating up to 50 °C ambient. Above that it derates linearly: 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel runs hot — say a packed enclosure near a furnace line or in a non-conditioned electrical room — the actual continuous current you can pull is the derated figure, not the nameplate 400 A. Plan the load schedule against the ambient the breaker actually sees.
Built-in undervoltage release
This variant ships with an undervoltage release (UVR) as the auxiliary release. That means the breaker trips automatically if the control voltage drops below a set threshold — useful for motor protection schemes where a loss of control power should drop the load, or for emergency-stop circuits that need a positive opening on voltage loss. There is no auxiliary switch included, so if you need a remote status contact, add one separately.
Physical fit and panel integration
Dimensions: 248 mm high, 138 mm wide, 110 mm deep. That is a standard SENTRON 3VA form factor — it mounts on a DIN rail or bolts directly into a switchgear chassis. The 110 mm depth leaves clearance behind a standard 200 mm deep enclosure backplate. Maximum power loss is 98.5 W at rated current, so factor that into the enclosure thermal calculation if the panel is tightly packed.
Environmental limits
Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C. The storage limit governs handling and warehousing, not running duty. If the breaker sits in a cold warehouse before installation, it is fine down to -40 °C as long as it is not energized.