What this MCCB delivers for the panel
The Siemens 3VA1225-5GF42-0JC0 is a 4-pole SENTRON molded case circuit breaker rated for 250 A continuous current at 40 °C, with a TM240 thermal-magnetic overcurrent release. Its 187 kA breaking capacity at 240 V and 121 kA at 415 V give it the headroom to clear high-fault events without cascading upstream — critical for a main or feeder breaker in a distribution panel where SCCR coordination matters. The 158 mm height, 140 mm width, and 70 mm depth fit the standard SENTRON 3VA footprint, so it drops into a panel already laid out for the series without re-drilling the mounting plate or re-routing busbars. Rated insulation voltage of 800 V means it's suited for 690 V line-to-line systems common in industrial and utility networks, and the IP40 front protection keeps debris out of the enclosure face in a clean panel environment.
Thermal derating and real-world current
The breaker holds its full 250 A rating up to 50 °C ambient. Above that, derating is linear: 243.3 A at 55 °C, 236.5 A at 60 °C, 229 A at 65 °C, and 223 A at 70 °C. If the panel internal temperature runs hot — say near a transformer or in a NEMA 12 enclosure — the 60 °C figure is the one to size against, not the catalog maximum.
Breaking capacity across voltage levels
The 187 kA at 240 V and 121 kA at 415 V cover most low-voltage distribution scenarios. At 440 V the rating drops to 36 kA, and at 690 V to 17 kA — still enough for most motor-control-center feeder applications at that voltage, but worth verifying against the transformer impedance and available fault current on site.
Integrated trip options and auxiliary contacts
The breaker ships with a shunt trip (STL) auxiliary release for remote tripping — useful for emergency-stop circuits or interlocking. It also includes 2 HQ auxiliary switches for status feedback to a PLC or SCADA. The integrated auxiliary trip is order code 3VA9688-0BL32, so if you need a spare or replacement, that's the part to source alongside this MCCB.