The Siemens 3VA2340-7KP42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for 400 A continuous current at 40 °C, with a 4-pole configuration and an ETU850 electronic trip unit. This is the line-protection version — no ground-fault monitoring built in, so if you need GF protection you'd add an external module or look at the GF variant. The interrupting ratings are the headline here: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 7.5 kA at 690 V.
At 55 °C it derates to 375 A, at 60 °C to 350 A, at 65 °C to 325 A, and at 70 °C to 300 A. That's a linear-ish drop of about 5 A per degree above 50 °C. If your panel ambient runs at 55 °C — common in a sealed, sun-loaded enclosure — you lose 25 A of headroom.
ETU850 trip unit — what it gives you
The adjustable response time (tr) ranges from 0.5 s to 17 s, which gives you selectivity coordination flexibility downstream. The N-conductor protection is adjustable: OFF or 20 % to 100 % of the phase setting. That matters for 4-wire systems where you need to protect the neutral against harmonic currents.
The 3VA2340-7KP42-0AA0 measures 248 mm high, 184 mm wide, and 110 mm deep. That's a 4-pole frame — wider than a 3-pole by roughly one pole pitch.