What this MCCB delivers
The Siemens 3VA2125-7HK36-0AA0 is a SENTRON molded case circuit breaker (MCCB) sized for line protection in distribution panels. It carries a rated continuous current of 25 A across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling, which simplifies panel thermal budgeting. The 3-pole design with an ETU340 electronic overcurrent release gives you adjustable long-time, short-time, instantaneous, and ground-fault protection curves, so you can coordinate downstream breakers without nuisance trips. Interrupting capacity is the headline here: 330 kA at 240 V, 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 clear a fault near the transformer secondary without upstream fuses needing to open — a real advantage for high-fault panels where series-rated combinations get complicated. At 690 V the rating drops to 3.7 kA, which still covers most motor-circuit faults in 690 V drives.
Panel fit and mounting
The 3VA2125-7HK36-0AA0 measures 105 mm wide, 181 mm high, and 86 mm deep. That 105 mm width is the standard 3-pole MCCB footprint for the SENTRON 3VA2 frame — it drops into the same DIN-rail or screw-mount slot as other 3VA2 breakers, so a panel laid out for a 3VA2125-8KQ42-0AA0 will accept this unit without drilling new holes or moving busbars. Front IP40 protection keeps dust out of the trip-unit compartment in a clean indoor panel; no washdown rating here, so keep it inside the enclosure.