What is a protection thyristor, Thyristor protection circuit, triac thyristor,

 T1235 Series 600 Vdrm 12 A Snubberless Triac AC Switch Surface Mount - D2PAK

https://www.futureelectronics.com/p/electromechanical--circuit-protection--power-thyristors/t1235-600g-tr-stmicroelectronics-2124396