This part is a kind of semiconductor called 2SK3550-01R.
Function of this product has Power MOSFET SuperFAP-G series Target.
Manufacturers : Fuji Electric
Image and pinout :
Some of the text within the PDF file :
www.DataSheet4U.com Fuji Power MOSFET SuperFAP-G series Target Specification 2SK3550-01R (900V/1.4Ω/10A) TO-3PF PRELIMINARY 1) Package Items Drain-Source Voltage Continuous Drain Current Pulsed Drain Current Gate-Source Voltage Repetitive and Non-Repetitive Maximum Avalanche Current Non-Repetitive Maximum Avalanche Energy Maximum Drain-Source dV/dt Peak Diode recovery dV/dt Maximum Power Dissipation Operating and Storage Temperature range This material and the information herein is the property of Fuji Electric Co.,Ltd. They shall be neither reproduced, copied, lent, or disclosed in any way whatsoever for the use of any third party nor used for the manufacturing purposes without the express written consent of Fuji Electric Co.,Ltd. 2) Absolute Maximum Ratings (Tc=25• Ž • @ VDS [ ... ]