Study of thermallay accelerated aging of transformer insulation paper in mineral oil and gas-to-liquid dielectrics using scanning electron microscopy (Sem), thermogravimetric analysis (tga) and x-ray diffraction (xrd)

Abstract

This paper reports novel comparative study results on the degradation of kraft paper immersed in mineral oil and gas-to-liquid dielectrics under accelerated aging at 120oC and 150oC for duration up to 1344 hours in a controllable oven. Tensile strength and degree of polymerization (DP)v of paper samples before and after aging were measured. Morphological changes were observed using SEM (scanning electron microscope). Degradation of cellulose from kraft paper including its crystallinity change was investigated through EDX (x-ray diffraction) analysis. Thermogravimetric (TG) analysis was used to study the thermal stability of the paper samples aged in the dielectrics. Experimental results showed that DP, and tensile strength of kraft paper decreased with aging. SEM observation indicated that micro globules detected in the aged paper sample and the diameter of micro globules increased with aging time and temperature. The EDX analysis showed that there were increase of crystallinity of aged paper samples. TG analysis showed that higher mass loss was found in aged samples compared to those new one. The initial decomposition temperature slightly reduced with aging time and temperature.