STMicroelectronics, BTA24-600BWRG, Circuit Protection Devices, Thyristor Surge

 BTA24 Series 600 Vdrm 25 A Flange Mount Snubberless Triac Thyristor - TO-220AB

https://www.futureelectronics.com/p/electromechanical--circuit-protection--power-thyristors/bta24-600bwrg-stmicroelectronics-1668227