The Siemens 3VA2340-4HM42-0AA0 is a 4-pole SENTRON molded case circuit breaker rated for a continuous current Iu of 400 A at 40 °C, holding that rating flat through 50 °C before it starts to derate — 385 A at 55 °C, 370 A at 60 °C, 355 A at 65 °C, and 340 A at 70 °C. The interrupting ratings tell you where this breaker can sit in the fault-current hierarchy: 121 kA at 240 V, 75.6 kA at 415 V and 440 V, 52.5 kA at 500 V, and 7.5 kA at 690 V. ETU330 electronic trip unit for line protection. N-conductor protection adjustable to OFF, 50%, or 100% of phase current. Rated insulation voltage 800 V.
The breaker measures 184 mm wide × 248 mm high × 110 mm deep. The 4-pole width (184 mm) is the standard for a 400 A frame in the 3VA2 family — it occupies four 45 mm module positions on a DIN rail or bolted to a mounting plate. The depth of 110 mm means it clears most standard enclosure back-panels without a sub-panel extension. The ETU330 is a basic electronic trip with no communication function, so all settings are adjusted via the rotary dials on the front face.
Maximum power loss is 96 W at rated current. The 96 W loss is at 400 A; at partial load the I²R losses drop proportionally.