What this MCCB carries and where it fits
The Siemens SENTRON 3VM1225-5EE36-0AA2 is a 3-pole molded case circuit breaker rated for 250 A continuous at 40 °C, with a TM220 thermal-magnetic overcurrent release designed for line protection. It breaks up to 187 kA at 240 V AC and 121 kA at 415 V AC, so it handles high-fault utility feeds or transformer secondaries without cascading upstream — the interrupting capacity at 415 V is the number that governs most industrial panel coordination studies. Insulation voltage is rated 800 V, operating voltage 690 V AC, which covers 480/600 V class systems with headroom. Thermal derating starts at 55 °C: 243.3 A at 55 °C, 236.5 A at 60 °C, 229.8 A at 65 °C, 223 A at 70 °C. If the panel ambient runs above 50 °C, size the load at the derated figure, not the 250 A nameplate. Power loss at full load is 57 W — negligible for ventilation planning in a standard enclosure, but worth noting if the panel is sealed and densely packed.
Panel fit and mounting
Dimensions are 70 mm deep, 105 mm wide, 158 mm high. It mounts on a DIN rail or directly to a backplate via the screw terminals. The front face carries IP40 protection — fine for a closed cabinet, not for washdown or outdoor exposure. No undervoltage release, no shunt trip, no communication module on this variant; it is a straight thermal-magnetic breaker with no auxiliary electronics.