What this MCCB is and what it does
The Siemens SENTRON 3VA2025-6KQ46-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 25 A continuous current across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. It carries the ETU860 electronic trip unit, which gives you adjustable long-time delay (0.5 to 25 s) and N-conductor protection configurable from OFF up to 160 %. The breaking capacity hits 242 kA at 240 V, 187 kA at 415/440 V, and still holds 121 kA at 500 V; at 690 V it drops to 3 kA, so this is a 400 V-class main or feeder breaker, not a 690 V machine protector.
Where it fits in the panel
Footprint is 140 mm wide by 181 mm tall by 86 mm deep — standard 4-pole MCCB envelope for a SENTRON 3VA2 frame. Front face carries IP40 protection, so it's fine inside a closed panel but not for washdown zones. The ETU860 includes communication and ground-fault summation (L+N), which means it can talk to a higher-level system and detect residual current without a separate core-balance CT.