MCCB for motor protection — 250 A, ETU350M, 330 kA at 240 V
The Siemens SENTRON 3VA2325-7MN32-0JL0 is a 3-pole molded case circuit breaker rated for 250 A continuous current (Iu) and built for motor protection duty. It carries the ETU350M electronic trip unit, which provides phase-failure detection and adjustable overload and short-circuit protection curves sized for motor loads — not just distribution feeders. Breaking capacity reaches 330 kA at 240 V, 242 kA at 415 V and 440 V, 187 kA at 500 V, and 52.5 kA at 690 V — figures that give the panel designer substantial SCCR headroom for high-fault installations. The frame measures 138 mm wide × 248 mm high × 110 mm deep, fitting the standard SENTRON 3VA mounting footprint. Panel builders should note the 37.5 W maximum power loss when sizing enclosure ventilation.
Trip unit and auxiliary configuration
The ETU350M overcurrent release supports motor protection with adjustable settings. A shunt trip (STL) auxiliary release is built in for remote tripping. The auxiliary contact block provides 2 auxiliary switches plus 1 trip alarm switch and 1 electrical alarm switch (HQ configuration). Rated insulation voltage is 800 V. The breaker includes a voltage trigger and a trip indicator for fault status at a glance. No undervoltage release or ground-fault monitoring is fitted on this variant.
Thermal derating and operating range
The 250 A rating holds from 40 °C through 50 °C. Derating begins at 55 °C (240 A), stepping down to 225 A at 70 °C. Operating ambient range is -25 °C to +70 °C; storage range is -40 °C to +80 °C.