The BT155W-1200T from WeEN Semiconductors is a Silicon Controlled Rectifier with Breakover Voltage 1200 V, Breakover Current 650 A, Gate Trigger Voltage 0.25 to 1 V, Gate Trigger Current 0.05 A, Temperature Operating Range -40 to 150 Degree C. Tags: Through Hole. More details for BT155W-1200T can be seen below.