25 A RMS, 700 V — the load-switching workhorse
The STMicroelectronics BTB24-700BRG is a standard triac in a TO-220-3 through-hole package, rated for 25 A RMS on-state current and 700 V off-state voltage. It handles AC loads up to roughly 6 kW on 230 V mains with margin, making it a common choice for industrial heating, motor speed controllers, solid-state relays, and large lighting banks. The 50 mA maximum gate trigger current (Igt) means it needs a driver transistor or optocoupler — a standard MCU GPIO cannot drive it directly. The 260 A non-repetitive surge rating at 60 Hz (Itsm) covers the inrush from incandescent lamps or motor starts without commutating off.
Industrial temperature range and mounting
The TO-220-3 through-hole package mounts into a standard tab for heatsinking — plan for a thermal interface material and a heatsink if the continuous current exceeds about 12 A RMS in still air. The hold current (Ih) is 80 mA maximum, which means the triac will stay latched once triggered as long as the load current stays above that threshold; low-power loads may need a dummy resistor to ensure reliable commutation.