What this MCCB carries — and what it clears
The Siemens 3VA1112-6EF36-0KA0 is a 3-pole SENTRON molded case circuit breaker rated 125 A at 40 °C, sized for line protection in distribution panels. Its TM240 thermal-magnetic release handles overloads and short-circuits; the integrated shunt trip (STL) lets you remotely trip the breaker via a control signal — useful for emergency-stop or interlock circuits where you need to kill power without pulling the handle. Breaking capacity is the headline here: 220 kA at 240 V AC, 154 kA at 415 V, 75.6 kA at 440 V, and 17 kA at both 500 V and 690 V. That 220 kA figure at 240 V means this breaker can safely interrupt a fault current up to 220,000 A without welding its contacts or rupturing the case — critical for high-fault installations like transformer secondaries or large motor control centers where the available fault current is well above what a standard 65 kA or 100 kA MCCB could handle. Rated insulation voltage is 800 V, so it's rated for 690 V systems with margin. Power loss maxes at 28.1 W — factor that into enclosure thermal calculations if you're packing several breakers in a tight panel.
Thermal derating and panel fit
The 125 A rating holds flat from 40 °C through 50 °C — no derating needed in a typical 50 °C panel ambient. Above that it drops: 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, 114 A at 70 °C. If your enclosure runs hot, size the upstream conductor and downstream load for the derated value, not the 125 A nameplate. Footprint: 130 mm high, 76.2 mm wide, 70 mm deep. That 70 mm depth is shallow enough to fit most standard distribution enclosures without a deep can — good for retrofit into existing panels where depth is tight. Three-pole, no trip indicator, no undervoltage release, no communication function, no ground-fault monitoring on this variant.