This part is a kind of semiconductor called S2055N.

Function of this product has SCRs.

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-263 D 2 Pak TO-92 * TO-218 TO-252 D-Pak TO-202 * TO-218X 3-lead Compak * TO-220 TO-251 V-Pak A K G (1 A to 70 A) E6 General Description The Teccor line of thyristor SCR semi-conductors are half-wave, unidirectional, gate-controlled rectifiers which complement Teccor's line of sensitive SCRs. Teccor offers devices with ratings of 1 A to 70 A and 200 V to 1000 V, with gate sensitivities from 10 mA to 50 mA. If gate currents in the 12 µA to 500 µA ranges are required, see “Sensitive SCRs” section of this catalog. Three packages are offered in electrically isolated construction where the case or tab is internally isolated to allow the use of low-cost assembly and convenient packaging techniques. [ ... ]

S2055N PDF Datasheet Download