What this MCCB is and what it does
The Siemens SENTRON 3VA2225-5KP32-0KF0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current of 250 A at 40 °C, designed for line protection in industrial power distribution panels. It carries a breaking capacity of 187 kA at 240 V and 121 kA at 415 V, meaning it can safely interrupt fault currents up to those levels without cascading upstream — critical for maintaining selective coordination in a plant's main or feeder distribution. The breaker includes a shunt trip (STL) release and an auxiliary switch with one auxiliary contact plus one trip alarm contact, allowing remote tripping and status feedback to a PLC or SCADA system. The communication function enables integration into a higher-level energy management or monitoring network, typical for SENTRON series breakers used in switchgear assemblies.
Thermal derating and current selection
The 3VA2225-5KP32-0KF0 holds its full 250 A rating up to 50 °C ambient. Above that, it derates linearly: 238 A at 55 °C, 225 A at 60 °C, 213 A at 65 °C, and 200 A at 70 °C. If the panel ambient runs hot — near a transformer or in a non-conditioned enclosure — the actual continuous current the breaker can carry drops, so size the load accordingly.
Breaking capacity across voltage levels
Breaking capacity varies with system voltage: 187 kA at 240 V, 121 kA at both 415 V and 440 V, 75.6 kA at 500 V, and 4.5 kA at 690 V. For a 480 V distribution panel, the 75.6 kA rating typically exceeds the available fault current, but at 690 V the 4.5 kA figure is the limit — verify the calculated SCCR at the point of installation.