Dielectric properties of mixed mineral and synthetic ester oil. Issue 9 (28th October 2020)

• Record Type: Journal Article
• Authors: Mahidhar, Gorla Durga Pawan; Somasundaram Karthikeyan, Amizhtan; Sarathi, Ramanujam; Taylor, Nathaniel; Edin, Hans
• Is Part Of: IET science, measurement & technology. Volume 14:Issue 9(2020)
• Page Start: 704
• Page End: 714
• Publication Date: 2020-10-28
• Subjects: corona -- power transformer insulation -- insulation testing -- partial discharges -- electric breakdown -- transformer oil -- ultraviolet spectroscopy -- frequency‐domain analysis; transformer insulation -- continuous breakdown studies -- AC voltage -- frequency‐domain spectroscopy studies -- dielectric properties -- synthetic ester oil -- corona inception voltage -- ultra‐high frequency technique -- statistical study -- breakdown voltage -- standard lightning impulse voltages -- mixed mineral oil -- UHF technique -- interfacial tension -- flash point -- ionic mobility -- UV‐vis spectroscopy -- liquid chemical stability -- polarisation current -- UHF signal energy analysis -- phase‐resolved partial discharge analysis -- DC voltages; Measurement -- Periodicals; Electrical engineering -- Periodicals; Electronics -- Periodicals; Nanotechnology -- Periodicals; Electromagnetism -- Periodicals; Medical instruments and apparatus -- Periodicals; 621.3
• DOI: 10.1049/iet-smt.2019.0227
• Languages: English
• ISSNs: 1751-8822

Abstract

Abstract : The dielectric properties of 20% synthetic ester oil mixed with mineral oil were studied for its potential applications as an insulator in transformers. The corona inception voltage of mixed oil under AC and DC voltages was measured by the ultra‐high frequency (UHF) technique. A statistical study of the breakdown voltage of mixed oil under AC, DC and standard lightning impulse voltages was carried out to obtain a database which would be useful for designing transformer insulation. Further, the mixture was subjected to continuous breakdown studies under AC voltage with lightning impulse voltages, at regular intervals and characterised through measurement of interfacial tension, flash point, ionic mobility as well as UV–vis spectroscopy and frequency‐domain spectroscopy studies to understand the liquid's chemical stability. The results of the study have shown that the mixture was stable even after several breakdowns. The ionic mobility and polarisation current have increased, indicating higher losses in the oil. UHF signal energy analysis and phase‐resolved partial discharge analysis have revealed a reduction in discharge activity with mixed oils.