What the breaking ratings mean for your fault-current study
The 3VA2125-5JQ46-0AA0 is a SENTRON molded case circuit breaker (MCCB) for line protection, carrying a continuous rated current of 25 A across the full ambient range from 40 °C to 70 °C — no derating needed up to that ceiling. The 187 kA interrupting rating at 240 V is the headline number that tells you it clears even a bolted fault on a high-capacity transformer secondary without the breaker venting or welding closed. At 415 V and 440 V that holds at 121 kA, dropping to 75.6 kA at 500 V, and 3.7 kA at 690 V. For a 4-pole breaker this means the three poles plus neutral all break together; the 800 V rated insulation voltage confirms it's built for 690 V line-to-line systems with margin. The ground-fault monitoring uses summation current formation on L + N conductor — it measures the vector sum, not a separate sensor.
DIN-rail footprint and panel integration
At 140 mm wide × 181 mm tall × 86 mm deep, this breaker occupies a standard 4-module-wide footprint on the DIN rail. The 0.6 W maximum power loss means no forced cooling required in a sealed enclosure — the heat is negligible even with adjacent breakers. Operating range is -25 °C to 70 °C; storage can go from -40 °C to 80 °C. No undervoltage release fitted, and no trip indicator on the front — the status is read from the handle position or via the communication interface.