What this MCCB is and what it does
The Siemens 3VA2125-7HK42-0AA0 is a SENTRON molded case circuit breaker — a 4-pole, 25 A rated device with an ETU340 electronic trip unit. It's built for line protection in distribution panels, sized to handle continuous current up to 25 A across the full ambient range from 40 °C to 70 °C without derating. Breaking capacity is the headline here: 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 53 kA at 690 V. That's a serious fault-current rating — it'll clear a high-energy arc flash without cascading upstream breakers, which matters when you're protecting a main or a feeder in a high-capacity plant.
Mounting and panel fit
Dimensions: 140 mm wide, 181 mm tall, 86 mm deep. That's a standard 4-pole MCCB footprint for the SENTRON 3VA2 frame — it'll drop into a panel that was laid out for a 3VA2-series breaker without re-drilling the mounting plate or re-routing bus bars. Front face carries IP40 protection — fine for a clean indoor panel, not rated for washdown. The ETU340 electronic trip gives you adjustable N-conductor protection (OFF or 100%) and a fixed time delay tr of 1300 ms.
Trip unit and protection characteristics
The ETU340 is an electronic overcurrent release. Rated insulation voltage Ui is 800 V, and latching endurance is 20,000 operations. Maximum power loss is 0.6 W. Operating temperature range: -40 °C to 70 °C. Storage range: -40 °C to 80 °C. No communication function, no ground-fault monitoring built in — this is a straight line-protection breaker, not a metering or GFCI device.