Study on the Effects of Thermal Aging on Insulating Paper for High Voltage Transformer Composite with Natural Ester from Palm Oil Using Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDS)

Abstract

Abstract:Mineral oil is widely used as liquid insulation in high voltage equipment. Due to environmental considerations, recently natural esters have been considered as naturally friendly liquid insulation candidates for high voltage transformers. In this experiment, transformer insulation paper was subjected to get accelerated aging test with copper strip in natural ester in a hermeneutical heat-resistant glass bottle at temperatures of 120 • C and 150 • C for 336 h, 672 h and 1008 h. The experimental results of Fourier transform infrared spectroscopy (FTIR) showed that the intensity of the absorbance peak of the O-H functional group decreased with aging, while the intensity of the C-H and C=O functional group absorbance peaks have increased with aging and the intensity of the C-O functional group absorbance peak has a tendency to increase with aging. The energy dispersive X-ray spectroscopy (EDS) experimental results showed that the weight percent of the element C increased with aging and the weight percent of the element O has decreased with aging. The experimental results show a good correlation between the degree of polymerization (DP) and the weight percent of O element. This indicates that EDS may be used as a new method for estimating the DP of transformer insulation paper.

Fourier Transform Infrared (FTIR) Spectroscopy Analysis of Transformer Paper in Mineral Oil-Paper Composite Insulation under Accelerated Thermal Aging

“…IEEE Standard C57.100-2011 also recommends using a copper conductor in experiments relating to transformer solid insulation [20]. A total amount of 10 g kraft paper, 8.75 g copper conductor, and 200 g mineral oil were placed in a hermetical glass bottle [17,21]. A pre-treatment process was carried Energies 2018, 11, 364 3 of 12 out on the mineral oil samples by putting the mineral oil in the oven for 24 h at 100 • C [9,11,17].…”

“…Energies 2018, 11, x FOR PEER REVIEW 3 of 12 on the mineral oil samples by putting the mineral oil in the oven for 24 h at 100 °C [9,11,17]. The purpose of this step was to reduce the amount of water content inside the mineral oil.…”

“…For insulating paper performance measurements, the spectroscopy technique and statistical analyses have been developed to obtain a correlation between the spectral response and the chemical properties of the paper. Several works have reported that this combined method has shown the possibility of using the spectroscopy technique for determining the degree of polymerization (DP) and water content of the transformer paper [6,[16][17][18]. Currently, destructive methods such as viscometry have been widely used for the direct measurement of DP [6,19].…”

Regeneration of Transformer Insulating Fluids Using Membrane Separation Technology

“…The function of the nitration is identified in the spectral region between 1600 cm −1 and 1650 cm −1 which is not seen in the spectral curve of purified oil, thus ensuring the disappearance of carboxylic acids and nitrated compounds in the purified oil. Further, increase in thermal oxidation with aging of oil is generally accompanied by nitration which introduces nitrogen oxides (NO, NO 2 and N 2 O) to the oil [26]. The effect of the nitration on the quality of the oil is similar to that of oxidation, which either increases the viscosity of the oil or involves in increasing insoluble sediments.…”

Physiochemical and Electrical Properties of Refined, Bleached and Deodorized Palm Oil under High Temperature Ageing for Application in Transformers

“…Previous studies revealed that the electrical and physiochemical properties of new PO are close to other types of natural esters and mineral oil (MO) [3][4][5][6]. The majority of these properties are comparable to other types of vegetable oils under ageing at temperatures ranging from 85 to 150 • C, which are maintained at acceptable levels according to standards [7][8][9][10][11]. Currently, the high temperature ageing performance of PO has not been well established and requires further investigation.…”