What this MCCB delivers — and where it fits
The Siemens 3VA2125-7HL42-0AA0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection, carrying 25 A continuously across the full ambient range from 40 °C to 70 °C with no derating needed. That flat thermal curve simplifies panel design — one device covers a warm cabinet without recalculating the load schedule. Its 4-pole construction handles three-phase plus neutral, with the N-conductor protection adjustable to OFF or 100 % of the phase rating. The ETU320 electronic trip unit provides selectable overload and short-circuit curves, giving the integrator precision over coordination with downstream breakers. Breaking capacity is the headline: 330 kA at 240 V AC, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 3.7 kA at 690 V. That 330 kA figure at 240 V means this breaker can be installed close to a large transformer or generator bus where fault current is extreme — no need for a current-limiting reactor or upstream fuse to protect the MCCB.
Panel fit and physical integration
Dimensions are 140 mm wide, 181 mm high, and 86 mm deep — a standard SENTRON 3VA2 footprint that drops into existing panel layouts without re-drilling the mounting plate. Front-face protection is IP40, adequate for a clean indoor enclosure; the breaker is not rated for washdown or outdoor exposure. The 3VA2125-7HL42-0AA0 carries no undervoltage release, no voltage trigger, no communication module, and no ground-fault monitoring — it is a pure line-protection device. If your BOM requires shunt trip or remote status, plan for an accessory add-on or step up to a 3VA2 variant with those features built in.