This part is a kind of semiconductor called Q6040K9.

Function of this product has Alternistors.

Manufacturers : Teccor

Image and pinout :

Some of the text within the PDF file :

Teccor offers bidirectional Alternistors with current ratings form 15 to 40 Amperes with voltages from 200 to 800 Volts as part of Teccor broad line of thyristors. Teccors alternistor has been specifically designed for applications which are required to switch highly inductive loads.

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Q6040K9 PDF Datasheet Download