The Siemens SENTRON 3VA1225-5EF42-0BA0 is a 4-pole molded case circuit breaker (MCCB) rated for 250 A at 40 °C, designed for line protection in distribution panels. It carries a TM240 thermal-magnetic release — the thermal element handles overloads, the magnetic element clears short-circuits — and includes an integrated undervoltage release (UVR) that trips the breaker when supply voltage drops below a set threshold, protecting downstream equipment from brownout damage.
Interrupting capacity and coordination
This MCCB delivers 187 kA interrupting capacity at 240 V, stepping down to 121 kA at 415 V, 75.6 kA at 440 V, 30 kA at 500 V, and 17 kA at 690 V. The 187 kA figure at 240 V is the highest in this class — it handles high-fault scenarios near the transformer secondary without cascading upstream. The rated insulation voltage is 800 V, so the breaker is suitable for 480/277 V and 600/347 V systems with headroom.
Thermal derating and power loss
The 250 A rating holds from 40 °C through 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. Maximum power loss is 59.5 W — a factor for enclosure heat rise calculations when grouping multiple breakers. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.
Mounting and panel fit
Dimensions are 140 mm wide, 158 mm high, and 70 mm deep. The 4-pole body at 140 mm width occupies four standard 35 mm DIN-rail module spaces (each pole ~35 mm). Depth of 70 mm leaves clearance for rear-mounted busbars and cable exits in a 200 mm deep enclosure. The TM240 release is factory-set; no trip indicator is fitted, and there is no communication function or ground-fault monitoring on this variant.