The Siemens SENTRON 3VA2125-8HK32-0AA0 is a 3-pole molded case circuit breaker (MCCB) rated for 25 A continuous current, fitted with an ETU340 electronic trip unit. It's designed for line protection — the primary feeder or distribution circuit in a panel, not motor or generator protection. The ETU340 gives you adjustable thermal and magnetic settings, which is what you want when coordinating downstream breakers in a selective system.
Breaking capacity and selectivity
This MCCB carries a 440 kA interrupting rating at 240 V AC and still holds 330 kA at 415 V and 440 V. At 690 V it's still good for 52.5 kA. That's a high-interrupting-capacity (HIC) device — it can sit close to a transformer secondary or a large generator bus without needing a current-limiting fuse upstream. The 800 V rated insulation voltage (Ui) confirms it's built for 690 V line-to-line systems with margin.
Panel fit and environment
Dimensions are 105 mm wide, 181 mm tall, 86 mm deep — that's a 4.13 by 7.13 by 3.39 inch footprint. It's a standard 3-pole MCCB form factor for DIN-rail or panel-mount installation. Front face carries an IP40 protection rating, so it's fine inside a closed panel but not for washdown or outdoor exposure. Operating temperature range is -25 °C to 70 °C; storage from -40 °C to 80 °C. Power dissipation is low at 0.5 W maximum, so heat buildup in a dense cabinet isn't a concern.