This part is a kind of semiconductor called BT138-600.

Function of this product has TRIACS.

Manufacturers : Comset Semiconductors

Image and pinout :

Some of the text within the PDF file :

SEMICONDUCTORS BT138 Series TRIACS FEATURE Glass passivated triacs in a plastic TO220 package. They are intended for use in applications requiring high bidirectional transient and blocking voltage capability and high thermal cycling performance. Typical applications include motor control, industrial and domestic lighting, heating and static switching. Compliance to RoHS. ABSOLUTE MAXIMUM RATINGS Value http://www.net/ Symbol Ratings Repetitive peak off-state voltage Repetitive peak reverse voltage RMS on-state current Non-repetitive peak on-state current Peak gate power Average gate power Storage temperature range Operating junction temperature Unit BT138-500 BT138-600 BT138-800 VDRM VRRM IT(RMS) ITSM PGM PG(AV) Tstg Tj 500 500 600 600 12 95 5 0.5 -45 to +150 110 800 V 80 [ ... ]

BT138-600 PDF Datasheet Download