Line protection MCCB with ETU340 — 25 A, 3-pole, 440 kA at 240 V
The Siemens 3VA2125-8HK36-0AA0 is a SENTRON molded case circuit breaker (MCCB) in the 3VA2 frame, configured as a line protection device with an ETU340 electronic overcurrent release. Rated continuous current Iu is 25 A across the full ambient range from 40 °C to 70 °C, so no derating is needed for warm panel environments. Three poles, rated insulation voltage Ui of 800 V. Breaking capacity runs from 440 kA at 240 V down to 53 kA at 690 V — that 440 kA figure at 240 V covers high-fault industrial services where the upstream transformer can deliver serious short-circuit current.
What the ratings mean for fit
The 25 A rating holds flat from 40 °C to 70 °C ambient — that's unusual for an MCCB and means you don't have to oversize for a hot enclosure. The ETU340 release is a solid-state trip unit with a fixed time delay tr of 1300 ms (both min and max settings), so it's set for selective coordination downstream: it lets a 25 A branch breaker clear a fault before this main trips. The 440 kA at 240 V is the highest breaking capacity in this class; it safely interrupts faults up to that level without cascading upstream. Front protection is IP40 — fine for a clean indoor panel, not for washdown areas.
Panel integration
Dimensions: 105 mm wide, 181 mm high, 86 mm deep. The 3VA2 frame mounts on a DIN rail or can be screw-mounted in a distribution panel. An optional motor drive (product extension available per the spec) allows remote reset or switching. Communication function is not built in — this is a standalone breaker, no fieldbus module on board. Power loss is a low 0.5 W maximum, negligible for thermal budgeting in a dense panel.