400 A MCCB with ETU550 — selectivity and thermal derating
The Siemens 3VA2340-5JP32-0AE0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current (Iu) in a 3-pole configuration, fitted with an ETU550 electronic overcurrent release. It carries a rated insulation voltage (Ui) of 800 V and delivers a breaking capacity of 187 kA at 240 V, 121 kA at 415/440 V, 75.6 kA at 500 V, and 17 kA at 690 V — figures that define its selectivity envelope in a distribution panel. The thermal derating curve is explicit: full 400 A up to 50 °C, then 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C. This means the breaker can be applied at its nameplate rating in most ventilated enclosures, but a 55 °C internal ambient (common in crowded switchboards) forces a 6% headroom reduction. Maximum power loss is 96 W, which should be factored into enclosure thermal calculations. The ETU550 release supports communication functions, enabling integration with higher-level monitoring systems for trip data and load profiling. The breaker includes four auxiliary switches HQ for status feedback to a PLC or SCADA. Mechanical endurance is rated at 15,000 operations, appropriate for a main feeder or large sub-feed application where switching frequency is moderate.
Panel integration — dimensions and auxiliary wiring
The breaker measures 138 mm wide, 248 mm high, and 110 mm deep. The 138 mm width is the standard 3-pole MCCB footprint for this SENTRON frame size; verify busbar spacing and door cutout against the existing panel layout. The four auxiliary switches HQ are pre-configured — no separate auxiliary block to order — and their wiring should be planned for the control voltage present in the panel. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. No undervoltage release or shunt trip is fitted on this variant.