This part is a kind of semiconductor called Q8012RH5.

Function of this product has Alternistor Triacs.

Manufacturers : Teccor Electronics

Image and pinout :

Some of the text within the PDF file :

l Se ec te U. L. G 39 CO 716 E R #E d P Fi le k ac ag es * NI ZE D * TO-220 *TO-218 *TO-218X TO-252 D-Pak TO-263 D 2 Pak TO-251 V-Pak MT2 MT1 G (6 A to 40 A) E4 General Description Teccor offers bidirectional alternistors with current ratings from 6 A to 40 A and voltages from 200 V to 1000 V as part of Teccor's broad line of thyristors. Teccor's alternistor is specifically designed for applications that switch highly inductive loads. A special chip offers the same performance as two thyristors (SCRs) wired inverse parallel (back-to-back), providing better turn-off behavior than a standard triac. An alternistor may be triggered from a blocking to conduction state for either polarity of applied AC voltage with operating modes in Quadrants I, II, and III. This new chip cons [ ... ]

Q8012RH5 PDF Datasheet Download