The Siemens SENTRON 3VA2225-6HN32-0BC0 is a 3-pole molded case circuit breaker rated for a continuous current Iu of 250 A at 40 °C, with an insulation voltage Ui of 800 V. The ETU350 electronic trip unit handles the overcurrent protection curve — no phase failure detection, no communication module onboard. Breaking capacity steps down across voltage: 242 kA at 240 V, 187 kA at 415 V and 440 V, 121 kA at 500 V, and 6 kA at 690 V.
Full 250 A holds through 50 °C ambient. At 55 °C it derates to 241 A, at 60 °C to 232 A, at 65 °C to 222 A, and at 70 °C to 213 A. The 105 mm width is three-pole standard for this frame size — it fits a standard SENTRON mounting pattern, no adapter plate needed. Maximum power loss is 50.5 W. That heat has to leave the enclosure — factor it into your thermal budget, especially in a sealed stainless steel panel.
What the ETU350 release does
The ETU350 is an electronic trip unit with LSI protection — long-time, short-time, and instantaneous. The undervoltage release drops the breaker when control voltage falls below its dropout threshold, which is standard for emergency-stop chains or undervoltage protection schemes. Mechanical endurance is rated at 20,000 operations.