The Schneider Electric G12E3A20 is a GoPact MCCB 125 thermal-magnetic circuit breaker, a 3-pole fixed-mount device rated 20 A at 40 °C with a 15 kA breaking capacity at 380/415 V AC. Its TM-D trip unit provides LI protection — thermal for overload (L) and magnetic for short-circuit (I) — making it a straight distribution breaker for panelboard or sub-feed duty where the fault current stays under 15 kA.
Above that temperature, thermal trip thresholds shift — the breaker will hold less current before the bimetal deflects. For a 20 A feeder on a 415 V supply with a prospective fault current under 15 kA, this breaker is sized correctly. Power dissipation per pole is 18.7 W at rated current — three poles total 56 W of heat inside the enclosure, so factor that into cabinet thermal calculations. Mechanical endurance is 30,000 cycles; electrical endurance under load at 415 V In is 8,000 cycles. For a distribution breaker that sees infrequent switching (maybe a few operations per year), that is ample. For a breaker used as a daily disconnect, the electrical life is the limiting number.
Fixed-mount, backplate mounting — no DIN-rail clip. The 75 mm width, 130 mm height, and 60 mm depth fit standard MCCB panel cutouts. Ambient operating range is -20 to 55 °C, storage -35 to 85 °C.