The G12F3A20 is a fixed-mount, 3-pole GoPact MCCB 125 with a TM-D thermal-magnetic trip unit rated at 20 A at 40 °C. That is the SCCR the panel designer needs for the branch circuit. The TM-D trip provides LI protection: the thermal element (L) handles overloads with a time-delay curve, and the magnetic element (I) trips instantaneously on short-circuit. This is a distribution-grade breaker (utilisation category A), not a motor-protection device — it is sized for cable and busbar protection in a 415/380 V AC distribution panel, not for direct motor starting duty. Overvoltage category III confirms it is intended for fixed-installation downstream of the service entrance, not for plug-connected equipment.
The toggle actuator gives positive visual indication of contact position. Accepts horizontal or vertical mounting flat on the backplate, which matters when the enclosure layout forces a 90-degree rotation. The IP20 finger-safe terminals are sufficient for a closed panel; no washdown rating here.
The breaker carries isolation suitability per EN/IEC 60947-2, meaning it can be used as a visible-break disconnect when the handle position indicates open contacts. The 8000 electrical cycles at rated current and 415 V, plus 30000 mechanical cycles, give a reasonable service life for a distribution panel that sees infrequent switching — not a daily-operate disconnect.
The 440 V rated insulation voltage and 415 V operational voltage at 50/60 Hz define the maximum system voltage this breaker can be applied on. Storage temperature range of -35 to 85 °C and operating range of -20 to 55 °C cover most indoor industrial environments. The altitude derating curve starts at 2000 m; above that, the dielectric and thermal margins reduce per IEC 60664-1.