25 A MCCB with ETU350 — what the ratings mean for your panel
The Siemens SENTRON 3VA2025-6HN46-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for a continuous current of 25 A across the full ambient temperature range from 40 °C to 70 °C — no derating needed up to that ceiling. That means it holds its 25 A rating in a warm enclosure without a sizing penalty. The ETU350 electronic trip unit provides adjustable overload and short-circuit protection with a curve that can be fine-tuned for selectivity downstream. The N-conductor protection is configurable to OFF or 100% of the phase rating. Breaking capacity is the headline here: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 3 kA at 690 V. Those numbers tell you this breaker can interrupt very high fault currents at common distribution voltages without upstream fuses — it's sized for main or large subfeed duty where available fault current is high. Rated insulation voltage Ui is 800 V, so the breaker is suitable for 690 V line-to-line systems with margin. Power dissipation is only 0.84 W per pole at rated current — negligible for enclosure thermal calculations.
Panel integration and mounting
The 3VA2025-6HN46-0AA0 measures 140 mm wide, 181 mm high, and 86 mm deep — a standard 4-pole MCCB footprint that fits SENTRON 3VA2 panelboards and distribution boards. Front-face protection is IP40, so it's protected against tools and wires >1 mm but not against water ingress; mount it inside an enclosure rated for the environment. No undervoltage release, no voltage trigger, no communication function, and no ground-fault monitoring on this variant. The trip indicator is also absent — fault status is read from the handle position and the ETU's local LED. If you need those options, look at the 3VA2 family with the appropriate suffix codes.