What this 250 A MCCB delivers
The Siemens SENTRON 3VA2325-5HL32-0KL0 is a 3-pole molded case circuit breaker (MCCB) rated for a continuous current Iu of 250 A, configured for line protection. It carries a breaking capacity of 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 17 kA at 690 V — so the interrupting rating drops sharply above 500 V, which matters when specifying for a 690 V distribution bus. The overcurrent release is an ETU320 electronic trip unit, and the auxiliary contact package includes 2 auxiliary switches plus 1 trip alarm switch and 1 electrical alarm switch HQ.
Thermal derating and panel integration
The breaker holds full 250 A rating from 40 °C through 50 °C, then derates to 240 A at 55 °C, 235 A at 60 °C, 230 A at 65 °C, and 225 A at 70 °C. If the panel ambient runs above 50 °C, the continuous current must be adjusted per this curve — a common oversight when packing multiple breakers into a sealed enclosure. Dimensions are 248 mm high by 138 mm wide by 110 mm deep, which fits the standard SENTRON 3VA panel footprint. Maximum power loss is 37.5 W, so heat dissipation within the enclosure needs to be accounted for in the thermal design.