This is one of the semiconductor types. This part name is Q6040K9.
This product has Alternistors functions.
Manufacturers of product is Teccor.
Image and pinout :
Q6040K9 PDF Datasheet
Some of the text files within the PDF file
Teccor offers bidirectional Alternistors with current ratings from 15 to 40 Amperes with voltages from 200 to 800 Volts as part of Teccor board line of thyristors. [ … ]
Please refer to the file for details.