Transformer is an electrical equipment that function to raise and lower an electrical voltage. It’s use is scattered anywhere, especially on a power plant. Generally on each power plant used a support equipment to raise the generator output voltage in the form of a generator transformer. The generator transformer is closely related to the heat generated by the electric current flowing in the primary and secondary coils while working and the heat depends on how much current flows on both coils. To find out how big the level of heat that occurs in the generator transformer it is necessary process thermography testing. Thermography test results in the form of color gradation from RGB color combinations (Red, Green, Blue) then pass the simulation stage used software Visual Basic by first determining which side of the side is used for the simulation process then the next to find out how big the average value of RGB (Red, Green, Blue) on the previously defined side. results From the existing simulation it can be seen whether the heat that occurs on each component of the transformer generator exceeds the maximum limit or not and there are components that have abnormalities.