400 A MCCB with ETU560 — line protection for high-fault panels
The Siemens SENTRON 3VA2340-5JQ42-0KH0 is a 4-pole molded case circuit breaker rated for 400 A continuous current (Iu) in a line protection version, built around the ETU560 electronic trip unit. This is the version you spec when you need adjustable long-time, short-time, instantaneous, and ground-fault protection curves — not a thermal-magnetic fixed-trip. The 400 A rating holds at 40 °C, 45 °C, and 50 °C; above that it derates to 375 A at 55 °C, 350 A at 60 °C, 325 A at 65 °C, and 300 A at 70 °C, so if your panel ambient runs hot, factor the thermal curve into your BOM margin. Short-circuit breaking capacity is the headline number for this frame: 187 kA at 240 V, 121 kA at both 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V. That SCCR profile means it handles high-fault utility feeds at low voltage and still clears a 690 V motor-circuit fault without cascading upstream. For a 400 A frame, the 121 kA at 415 V is the spec that usually decides the panel coordination study.
Trip unit, auxiliaries, and communication
The ETU560 electronic trip unit supports communication — it can talk to the higher-level control system via the SENTRON communication bus, so you get remote trip indication, current metering, and parameter adjustment without opening the panel door. The auxiliary contact block ships with 2 auxiliary switches plus 1 trip alarm switch HQ, which covers the feedback signals a PLC typically needs: breaker closed, breaker open, and trip event. A shunt trip release (STL) is integrated for remote emergency-off or undervoltage-initiated tripping. Ground-fault monitoring uses summation current formation on L + N, so it detects leakage without a separate toroid. Rated insulation voltage Ui is 800 V, which matches the 690 V breaking rating — this breaker is insulated for 690 V line-to-line service. Maximum power loss is 96 W, which is the heat you need to vent in the enclosure; for a 400 A frame that is typical and manageable with natural convection in a ventilated panel. Mechanical endurance is 15,000 operations — not a daily-switch duty class, but fine for a distribution feeder that cycles once or twice a month.
Physical fit and environmental limits
Dimensions: 184 mm wide, 248 mm high, 110 mm deep. Operating temperature range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.