This part is a kind of semiconductor called 40TPS12A.

Function of this product has Phase Control SCR.

Manufacturers : Vishay Siliconix

Image and pinout :

Some of the text within the PDF file :

40TPS...A/40TPS... High Voltage Series Vishay High Power Products Phase Control SCR, 35 A DESCRIPTION/FEATURES 2 (A) The 40TPS...A High Voltage Series of silicon controlled rectifiers are specifically designed for medium power switching and phase control applications. The glass passivation technology used has reliable operation up to 125 °C junction temperature. Low Igt parts available. Typical applications are in input rectification (soft start) and these products are designed to be used with Vishay HPP input diodes, switches and output rectifiers which are available in identical package outlines. This product has been designed and qualified for industrial level. TO-247AC 1 (K) (G) 3 PRODUCT SUMMARY VT at 40 A ITSM VRRM < 1.45 V 500 A 800/1200 V MAJOR RATINGS AND CHARACTERISTICS PA [ ... ]

40TPS12A PDF Datasheet Download