What the ratings mean for your panel
The Siemens SENTRON 3VA2340-5JQ42-0KL0 is a 4-pole molded case circuit breaker (MCCB) rated 400 A continuous at 40 °C, with a breaking capacity of 187 kA at 240 V AC and 121 kA at 415 V AC. That 187 kA figure at 240 V means it can safely interrupt a fault current up to 187,000 A without welding contacts or rupturing the case — critical for high-fault installations like transformer secondaries or large motor control centers. At 690 V the interrupting rating drops to 7.5 kA, so verify the available fault current at your service voltage before specifying. The breaker carries a full rated current of 400 A from 40 °C up to 50 °C, then derates linearly to 300 A at 70 °C. If your panel ambient runs above 50 °C, you need to account for that derating in the load schedule — a 375 A load at 55 °C is still within the curve. This MCCB includes a communication function and is fitted with a shunt trip release (STL) plus an auxiliary switch configuration: 2 auxiliary switches + 1 trip alarm switch + 1 electrical alarm switch HQ.
Panel integration and footprint
The breaker measures 248 mm high by 184 mm wide by 110 mm deep — a standard SENTRON 3VA2 frame size. It mounts on a DIN rail or directly to a backplate via the screw terminals. The 110 mm depth leaves room for cable bending radius in a 400 mm deep enclosure. Maximum power loss is 96 W at rated current, so factor that into the enclosure thermal calculation — a sealed cabinet may need forced ventilation or a larger volume to stay below the 70 °C operating maximum.