The STMicroelectronics T830-8FP is an 800 V, 8 A RMS Snubberless alternistor triac in a TO-220FPAB full-pack, through-hole package. It belongs to the Snubberless™ series, meaning it is designed for inductive-load switching without the usual RC snubber network across the main terminals — the device's own turn-off dV/dt capability handles the commutation. Typical applications include AC motor speed controls, industrial heating, lighting dimmers, and solid-state relays where the load is resistive or moderately inductive and the line voltage is 230 VAC or 400 VAC nominal.
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The 800 V off-state voltage gives headroom for 400 VAC line applications — the peak of a 400 VAC sine wave is about 565 V, so the 800 V rating leaves margin for mains transients without avalanche. The 8 A RMS on-state current is the continuous load rating; for motor or heater loads with inrush, the non-repetitive surge capability of 80 A at 50 Hz and 84 A at 60 Hz covers the cold-start spike. Gate trigger current is 30 mA max with a 1.3 V max gate trigger voltage — standard logic-level drive from a microcontroller or optocoupler will fire it, but the 50 mA holding current means the load must draw at least that much to stay latched; a very light load may drop out at the zero-cross.