MCCB for line protection with ETU350 trip unit
The Siemens SENTRON 3VA2325-5HN32-0DC0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current Iu of 250 A, fitted with an ETU350 electronic trip unit and configured for line protection duty. The interrupting capacity reaches 187 kA at 240 V AC and 121 kA at 415 V and 440 V, dropping to 75.6 kA at 500 V and 17 kA at 690 V — figures that govern the available fault current the breaker can safely clear at the point of installation. The ETU350 provides adjustable overload and short-circuit protection curves, making this MCCB suitable for main feeder or large subfeed applications where coordination with downstream devices matters.
Thermal derating and operating limits
The 250 A rating holds at ambient temperatures up to 50 °C; above that, the breaker derates to 240 A at 55 °C, 235 A at 60 °C, 230 A at 65 °C, and 225 A at 70 °C. The operating temperature range spans -25 °C to 70 °C, with storage from -40 °C to 80 °C. Maximum power loss is 40 W. For panel builders, the 138 mm width, 248 mm height, and 110 mm depth define the mounting footprint on a DIN rail or backplate.
Auxiliary contacts and undervoltage release
This MCCB ships with 2 auxiliary switches (HQ version) for status feedback to a PLC or annunciator panel. An undervoltage release (UVR) is integrated — when control voltage drops, the breaker trips, providing a coordinated shutdown on loss of control power. The UVR design is specified as part of the basic switch assembly (3VA2325-5HN32-0AA0), and the integrated auxiliary trip module carries order code 3VA9608-0BB25. Latching endurance is rated at 15,000 operations.