A Thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current trigger, and continue to conduct while they are forward biased. Thyristors are synonymous to Silicon-Controlled Rectifier (SCR).
https://www.rapidonline.com/pdf/151290_da_en_01.pdf
https://www.rapidonline.com/pdf/151290_da_en_01.pdf
