Siemens SENTRON 3VA1225-5EF32-0CA0 — 250 A MCCB with TM240 release
The Siemens SENTRON 3VA1225-5EF32-0CA0 is a 3-pole molded case circuit breaker rated for 250 A continuous current (Iu) at 40 °C ambient, with a TM240 thermal-magnetic overcurrent release. It carries a breaking capacity of 187 kA at 240 V AC and 121 kA at 415 V AC — figures that place it in the high-interrupting category for industrial distribution panels where fault currents exceed typical 50–65 kA ranges. This is the line protection version, meaning it is configured for feeder and main breaker duty rather than motor branch-circuit protection. An undervoltage release (UVR) is integrated; the auxiliary trip accessory is order code 3VA9608-0BB24.
The interrupting ratings span four voltage levels: 187 kA at 240 V, 121 kA at 415 V, 36 kA at 440 V, and 17 kA at 690 V (–). At 415 V, 121 kA exceeds the typical 50–65 kA SCCR found in most North American panel schedules — this breaker is sized for high-fault installations such as transformer secondaries or large motor control centers where the available fault current is known to be above 100 kA. Thermal derating begins at 55 °C: the breaker carries the full 250 A up to 50 °C (–), then steps down to 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C (–). For a panel that runs at 60 °C internal ambient, the usable current is 236.5 A — a 5.4 % reduction from the nameplate rating.