Parametric fit and blocking capability
The BTW68-800RG is a standard-recovery SCR rated for 800 V off-state blocking and 30 A RMS on-state conduction. That 800 V Vdrm means it holds off rectified 480 VAC line peaks with margin — the 1.5× derating rule for inductive loads is satisfied without stacking devices. On-state voltage drop Vtm is 2.1 V max at the rated current; the conduction loss at 30 A RMS is roughly 63 W peak, which the TOP-3 copper tab dissipates into a heatsink. The 75 mA holding current ensures the device stays latched after the gate pulse drops, typical for phase-control circuits.
Surge ruggedness and gate drive
Non-repetitive surge current is 400 A at 50 Hz and 420 A at 60 Hz (half-sine wave, Tj initial 25 °C). This covers motor inrush, capacitor charging, and fuse-clearing events — the silicon junction absorbs the thermal transient without failure as long as the surge duration stays under 10 ms. Gate trigger current Igt is 50 mA max, gate trigger voltage Vgt 1.5 V max — compatible with standard 5 V logic driving a series resistor. The 20 µA off-state leakage at 800 V is negligible for standby power budgets.
Package and thermal path
TOP-3 (TO-247 style) through-hole package with a large metal tab — the case is the anode connection. The tab must be electrically isolated from the heatsink unless the circuit common is the anode rail.