125 A MCCB with 187 kA SCCR — what the ratings mean for your panel
The Siemens SENTRON 3VA1112-5EF32-0JA0 is a 3-pole molded case circuit breaker rated for 125 A continuous current across the 40 °C to 50 °C ambient range, with no derating needed up to that point. At 240 V AC it interrupts faults up to 187 kA — that is the SCCR (short-circuit current rating) that governs whether this breaker coordinates with upstream gear in high-fault installations like transformer secondaries or large motor control centers. The TM240 thermal-magnetic release provides fixed-time overcurrent protection for line distribution or feeder circuits, not motor overload curves.
Breaking capacity by voltage — selectivity planning
The interrupting rating drops as system voltage rises: 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That means in a 480 V panel this breaker still clears 75.6 kA, which covers most industrial service-entrance and sub-distribution scenarios. At 690 V the 17 kA rating suits it for downstream branch protection rather than main incoming duty.
Thermal derating and shunt trip integration
Above 50 °C the 125 A rating begins a gentle derating curve — 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, 114 A at 70 °C. The shunt trip release (STL) allows remote tripping via a separate control voltage, useful for emergency-stop or interlock circuits. The breaker measures 130 mm high, 76.2 mm wide, 70 mm deep — fits standard 3-pole MCCB panel cutouts without special adapters.