Fourier transform infrared spectroscopy (FTIR) analysis of transformer insulation paper in natural ester

Transformer insulation paper especially kraft paper is extensively used as transformer solid insulation since a long time ago. Natural ester from palm is considered as a candidate of naturally friendly liquid insulation for high voltage transformers. Accelerated thermal aging can change the structure of transformer insulation paper in natural ester. In this paper, transformer insulation paper get accelerated aging test in natural ester at temperature 150°C for varying durations. This research was conducted by soaking transformer insulation paper in natural ester which was thermal aged at temperature 150°C from 336 hours, 672 hours and 1008 hours. The object of experiment on this research is copper which is wrapped around by transformer insulation paper placed in natural ester. The results of the experiment showed the structural changes of transformer insulation paper under accelerated thermal aging with fourier transform infrared spectroscopy (FTIR). Microstructure on the surface of transformer insulation paper changing during accelerated thermal aging was observed by using scanning electron microscope (SEM). The FTIR results of transformer insulation paper showed the intensity of peaks absorbance of O-H functional group (at wavenumber 3273 cm
⁻¹
and 3325 cm
⁻¹
), the intensity of peaks absorbance of C-H functional group (at wavenumber 2855 cm
⁻¹
and 2922 cm
⁻¹
), the intensity of peak absorbance C=O functional group (at wavenumber 1743 cm
⁻¹
) and the intensity of peak absorbance of C-O functional group (at wavenumber 1159 cm
⁻¹
). The SEM results of transformer insulation paper showed the paper surface morphology. Analysis of structural changes with FTIR can be explained by aging mechanisms of transformer insulation paper in natural ester.