What this 3VA1225-5EF42-0AD0 is and what it does
The Siemens SENTRON 3VA1225-5EF42-0AD0 is a 4-pole molded case circuit breaker (MCCB) designed for line protection in distribution panels and switchgear. Its TM240 thermal-magnetic release provides overload and short-circuit protection for feeder circuits, with a rated current of 250 A at 40 °C ambient — the same rating holds at 45 °C and 50 °C, then derates to 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. The 187 kA breaking capacity at 240 V AC means it can safely interrupt fault currents up to that level without upstream cascading; per the datasheet, the interrupting rating drops to 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V.
Where it fits in the panel
The 3VA1225-5EF42-0AD0 mounts on a DIN rail or directly to a backplate in a standard distribution enclosure. Its dimensions — 158 mm height, 140 mm width, 70 mm depth — match the SENTRON 3VA family footprint, so it drops into existing panel layouts without rewiring if the busbar and lug kit are compatible. The unit ships with three auxiliary switches (HQ type) pre-installed, which can be wired for status feedback to a PLC or remote indication.
Key ratings and what they mean for selection
The rated insulation voltage of 800 V sets the maximum system voltage the breaker can withstand without breakdown — suitable for 690 V line-to-line systems common in industrial plants. The maximum power loss of 57 W is the heat dissipated at full rated current; panel ventilation or spacing should account for this to keep the ambient within the 70 °C operating maximum. The TM240 release is a fixed thermal-magnetic trip unit — no electronic adjustment, no ground-fault monitoring, no communication function. This is a straightforward, rugged breaker for standard feeder protection where selectivity coordination is done via the trip curve.