Siemens SENTRON 3VA1225-5EF32-0BH0 — 250 A MCCB with High Interrupting Capacity
The Siemens SENTRON 3VA1225-5EF32-0BH0 is a 3-pole molded case circuit breaker (MCCB) rated for 250 A continuous current at 40 °C ambient, designed for line protection in distribution panels. It carries a 187 kA interrupting capacity at 240 VAC — that means it can safely clear a fault current up to 187,000 amps without welding contacts or rupturing the case, which is critical for high-fault installations like transformer secondaries or large motor control centers. At 415 VAC the interrupting rating is 121 kA, and it still holds 75.6 kA at 440 VAC, 30 kA at 500 VAC, and 17 kA at 690 VAC, covering most industrial voltage levels. The breaker includes an undervoltage release (UVR) as standard — if the supply voltage drops below a set threshold, the UVR trips the breaker, preventing motor loads from re-accelerating uncontrolled when power returns. It also comes with two auxiliary switches and one trip alarm switch (HQ), giving you remote status indication for open/closed and fault conditions. The insulation voltage is rated at 800 V, so the breaker is suitable for 690 V systems with margin.
Thermal Derating and Power Loss
The 250 A rating holds flat from 40 °C to 50 °C ambient. Above that, derate linearly: 243 A at 55 °C, 237 A at 60 °C, 230 A at 65 °C, and 223 A at 70 °C. If your panel runs hot — say near a drive cabinet or in a non-climate-controlled enclosure — account for that drop. Maximum power loss is 59.5 W, which matters for enclosure ventilation calculations.
Physical Fit and Mounting
The 3VA1225-5EF32-0BH0 measures 105 mm wide, 158 mm high, and 70 mm deep. That 105 mm width is a standard 3-pole MCCB footprint — it fits the same panel cutout and busbar spacing as other SENTRON 3VA frame breakers. The 70 mm depth means it projects less than 3 inches from the mounting surface, leaving room for wiring gutters or a shallow enclosure. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C.