400 A MCCB with ETU320 — what the ratings mean for panel fit
The Siemens 3VA2440-5HL32-0DC0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current (Iu) across a 3-pole configuration, making it the main feeder or large-motor protection in a 400 V industrial distribution panel. The ETU320 electronic trip unit gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves — not a fixed thermal-magnetic response, so coordination studies actually mean something downstream. Breaking capacity is voltage-dependent: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. At 415 V — the common European industrial supply — 121 kA SCCR means this breaker clears a bolted fault without upstream fuses needing to open, provided the panel bus bracing holds. That is a high-interrupting rating for a 400 A frame; you are not forced into a current-limiting fuse coordination. Thermal derating is published per degree: full 400 A up to 50 °C, then 384 A at 55 °C, 376 A at 60 °C, 368 A at 65 °C, and 360 A at 70 °C. If the panel ambient runs at 55 °C, you lose 16 A of headroom — factor that into the load schedule before committing the BOM line.
Undervoltage release and auxiliary switching
This variant ships with an undervoltage release (UVR) fitted — the basic switch is order code 3VA2440-5HL32-0AA0, and the integrated auxiliary trip is 3VA9608-0BB25. The UVR drops the breaker on loss of control voltage, which is standard for emergency-stop circuits or undervoltage protection on motor feeders. Two auxiliary switches (HQ type) are built in for status feedback to a PLC or remote indication panel. Rated insulation voltage Ui is 800 V, so the breaker is rated for 690 V systems without derating the internal creepage distances. Maximum power loss at rated current is 66 W — plan ventilation accordingly if the MCCB is enclosed in a low-volume pull-box rather than a ventilated switchboard.