This part is a kind of semiconductor called S1200NC25D.

Function of this product has Symmetrical Gate Turn-Off Thyristor.

Manufacturers : IXYS

Image and pinout :

Some of the text within the PDF file :

WESTCODE An IXYS Company Date:- 8 Apr, 2005 Data Sheet Issue:- 3 Symmetrical Gate Turn-Off Thyristor Type S1200NC25# Absolute Maximum Ratings VDRM VRSM VRRM VRSM VOLTAGE RATINGS Repetitive peak off-state voltage, (note 1). Non-repetitive peak off-state voltage, (note 1). Repetitive peak reverse voltage. Non-repetitive peak reverse voltage. MAXIMUM LIMITS 2500 2600 100-2000 100-2000 UNITS V V V V ITGQM Ls IT(AV)M IT(RMS) ITSM ITSM2 I2t di/dtcr PFGM PRGM IFGM VRGM toff ton Tjop Tstg RATINGS Maximum peak turn-off current, (note 2). Snubber loop inductance, ITM=ITGQM, (note 2). Mean on-state current, Tsink=55°C (note 3). Nominal RMS on-state current, 25°C (note 3). Peak non-repetitive surge current tp=10ms. Peak non-repetitive surge current, (Note 4) I2t capacity for fusing tp=10ms. [ ... ]

S1200NC25D PDF Datasheet Download