The Schneider Electric G12F3F100 is a GoPact MCCB 125 — a fixed-mount, 3-pole moulded case circuit breaker rated 100 A at 40 °C with a TM-D thermal-magnetic trip unit providing LI (overload and short-circuit) protection. The TM-D trip unit uses a thermal bimetal for overload (L) and a magnetic solenoid for short-circuit (I); the magnetic pickup is fixed, so you cannot adjust the instantaneous trip threshold. That makes this a distribution-grade breaker (Category A utilisation), not a motor-protection device with adjustable magnetic settings. For motor branch circuits you would typically pair it with a contactor and overload relay upstream.
Mounting and integration into a panel
Mounts fixed to a backplate via the 25 mm connection pitch — no DIN rail adapter here, it bolts directly. The front-facing screw terminals (both line and load sides) make for straightforward busbar or cable connections in a distribution board. Pollution degree 3 (IEC 60664-1) means it is rated for the conductive-dust and condensation environment typical of an industrial control panel, not a clean room. Overvoltage category III confirms it is intended for the fixed installation downstream of the main service entrance. Ambient operating range is -20 to 55 °C, storage -35 to 85 °C, which covers most unheated electrical rooms. At 2000 m altitude no derating is needed; above that, up to 5000 m, the dielectric strength drops and you must derate the voltage and current per the manufacturer's curve.