The Siemens 3VA1112-4EF32-0AG0 is a SENTRON molded case circuit breaker (MCCB) rated for line protection — 125 A continuous at 40 °C, 3-pole, with a TM240 thermal-magnetic overcurrent release. Its interrupting capacity hits 121 kA at 240 V and still holds 75.6 kA at 415 V, so it handles high-fault service-entrance or distribution panels where the available short-circuit current is substantial. The 70 mm depth and 76.2 mm width keep it within a standard MCCB footprint for retrofit into existing SENTRON or third‑party panelboards — no re-drilling of the mounting plate needed if the previous breaker was a 3VA or similar 3‑pole frame.
The 125 A rating holds flat from 40 °C up to 50 °C, then steps down to 122 A at 55 °C, 120 A at 60 °C, and 114 A at 70 °C. The 28.1 W maximum power loss is manageable for a 125 A frame; just keep the surrounding air moving if you stack breakers.
The interrupting ratings step down cleanly: 121 kA at 240 V, 75.6 kA at 415 V, 52.5 kA at 440 V, and 11.9 kA at both 500 V and 690 V.
The 130 mm height and 70 mm depth leave room for cable bending below the line terminals. The trip indicator gives a visual flag on the front bezel — useful for a maintenance walk‑by without opening the panel door.