The Siemens SENTRON 3VA1112-4EF36-0KC0 is a 3-pole molded case circuit breaker rated for 125 A continuous current, with a TM240 thermal-magnetic overcurrent release and an integrated shunt trip (STL). It's built for line protection — meaning it sits upstream of a distribution bus or a feeder, not on a motor branch. The interrupting ratings climb to 121 kA at 240 V AC and 75.6 kA at 415 V AC, so it handles high-fault scenarios without cascading upstream. The 800 V rated insulation voltage (Ui) gives headroom for 480 V or 600 V class panels.
Mounting footprint: 130 mm tall, 76.2 mm wide, 70 mm deep. That 76.2 mm width is a standard 3-pole MCCB pitch — it drops into a SENTRON panelboard or a DIN-rail adapter without surprises. The front face carries IP40 protection, so it's fine inside a closed enclosure but not for washdown areas. Two HQ auxiliary switches are built in, giving you status feedback for a PLC or a remote indication lamp.
Thermal derating is minimal up to 50 °C — still 125 A. At 55 °C it drops to 120 A, at 60 °C to 117.5 A, and at 70 °C to 112.5 A. That's a gentle slope; you don't lose much headroom in a warm panel. The TM240 release is a fixed thermal-magnetic type — no interchangeable trip units, so the breaker is factory-set for 125 A. Latching endurance is rated at 15 000 operations, which is typical for a distribution MCCB — not a switching duty cycle, but fine for infrequent manual isolation.