What this MCCB is and what it does
The Siemens SENTRON 3VA2225-5HN32-0HL0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current Iu of 250 A, with a rated insulation voltage Ui of 800 V. It is configured for line protection — meaning it guards feeders and distribution circuits against overload and short circuit, not motor or generator protection. The interrupting capacity at 240 V is 187 kA, at 415 V and 440 V it is 121 kA, and at 690 V it drops to 5.1 kA — so the voltage class of your installation determines the fault current the breaker can safely clear.
Trip unit and auxiliary releases
The overcurrent release is an ETU350 electronic trip unit, which provides adjustable long-time, short-time, instantaneous, and ground-fault protection curves — typical for selective coordination in distribution panels. The breaker includes a shunt trip (STL) for remote tripping, and the auxiliary contact block carries 2 auxiliary switches, 1 trip alarm switch, and 1 electrical alarm switch (HQ configuration). A voltage trigger is present; undervoltage release and phase failure detection are not fitted on this variant.
Thermal derating and operating limits
The breaker is rated 250 A continuously at ambient temperatures up to 50 °C. Above that, the current must be derated: 241 A at 55 °C, 232 A at 60 °C, 222 A at 65 °C, and 213 A at 70 °C. The operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. Maximum power loss is 48 W. These numbers matter when sizing the enclosure ventilation — a fully loaded breaker at 250 A dissipates nearly 50 W, which adds up in a multi-breaker panel.
Physical footprint and panel integration
Dimensions are 105 mm wide, 181 mm high, and 86 mm deep. The 105 mm width is standard for a 3-pole SENTRON 3VA2 frame — it mounts on a DIN rail or can be screw-fixed to a backplate. The depth of 86 mm includes the arc chamber and terminals; allow clearance for cable bending radius and the shunt trip wiring.