The Siemens 3VA1112-6EF36-0CA0 is a SENTRON molded case circuit breaker (MCCB) rated 125 A at 40 °C, with a 220 kA interrupting capacity at 240 V — that is the short-circuit rating that governs its use in high-fault panels like mains feeders or transformer secondaries where available fault current is high. The 3-pole design and line-protection profile (TM240 thermal-magnetic release) make it a straight fit for protecting cables and busbars, not motor circuits.
Ratings that decide the BOM line
Rated current holds flat at 125 A from 40 °C through 50 °C, then derates to 122 A at 55 °C, 120 A at 60 °C, 117 A at 65 °C, and 114 A at 70 °C. That thermal curve means the breaker can be applied at its full nameplate in a 50 °C panel without derating — common in enclosed switchgear or outdoor cabinets. Interrupting capacity drops from 220 kA at 240 V to 154 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V, so verify the available fault current at the installation voltage before specifying. Power loss is 30.6 W maximum — relevant for thermal budgeting in a multi-breaker enclosure.
The 3-pole frame is designed for DIN-rail mounting in standard distribution panels.