What the ratings mean for fit
The 3VA2340-5HN42-0DH0 is a Siemens SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, with an ETU350 electronic trip unit. The 4-pole configuration covers three-phase plus neutral, and the 800 V rated insulation voltage (Ui) gives headroom for 480 V or 600 V class systems. The breaking capacity varies by system voltage: 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 — so at 480 V you interpolate between the 440 V and 500 V figures, which is typical for a large-frame MCCB protecting a transformer or main feeder. The ETU350 is a basic electronic trip unit with adjustable overload and short-circuit settings, but no communication, phase-failure detection, or ground-fault monitoring — it's a line-protection device, not a motor-protection or power-monitoring breaker. The included undervoltage release (UVR) and the auxiliary contact pack (2 auxiliary switches + 1 trip alarm switch HQ) cover the common control-wiring needs for shunt-trip and status feedback in a distribution panel. Thermal derating is published: the breaker holds 400 A up to 50 °C, then drops to 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. If the panel ambient runs above 50 °C, you need to account for that in the feeder sizing. Maximum power loss is 98.5 W, which matters for enclosure heat load calculations.
Panel integration and wiring
The breaker measures 184 mm wide by 248 mm high by 110 mm deep — a standard footprint for a 400 A 4-pole MCCB in the SENTRON 3VA2 frame. It mounts with four screws to a backplate or mounting rail; no DIN-rail clip on this frame size. The undervoltage release and auxiliary contact pack are factory-integrated, so no field-assembly of those accessories is needed — just wire the line and load lugs, connect the UVR coil to the control voltage, and terminate the auxiliary contacts into the PLC or status-monitoring input. The ETU350 trip unit is the supplied basic switch variant (3VA2340-5HN42-0AA0) with the electronic trip module built in. No communication module, so no Modbus or PROFIBUS interface — this is a straightforward distribution breaker, not a smart breaker. The 4-pole design with neutral protection is typical for North American 120/208 V or 277/480 V wye systems where the neutral needs overcurrent protection.