400 A MCCB with ETU550 trip unit — what the ratings mean for your panel
The Siemens SENTRON 3VA2340-5JP32-0AC0 is a 3-pole molded case circuit breaker rated for 400 A continuous current at 40 °C, with the ETU550 electronic trip unit managing overcurrent protection. That 400 A holds flat through 50 °C, then derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C — so in a warm enclosure you size for the derated figure, not the nameplate. Breaking capacity runs 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. That 187 kA at 240 V is the headline number for high-fault北美 panels; the 121 kA at 415 V covers most European industrial distribution. The rated insulation voltage of 800 V means it's rated for 690 V systems with margin. IP40 on the front keeps dust out of the operator interface but expects a clean enclosure — not a washdown location.
Line protection, communication, and auxiliary contacts
This is the line protection version — no voltage trip, no undervoltage release, no ground fault monitoring. It does carry a communication function, so it can talk to a BMS or PLC for monitoring and remote trip indication. The auxiliary contact version is 2 auxiliary switches HQ, giving two form-C contacts for status feedback. Max power loss is 96 W at rated current — factor that into enclosure thermal calculations. Mechanical endurance is 15,000 operations. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C.