Dielectric and Gas Production Characteristics of Synthetic Esters Under Different Discharge Energies

With the increasing demand for safety and sustainable development in the power industry, the research on synthetic esters as a new type of insulating oil is becoming more and more important. This article takes pentaerythritol ester as the research object, simulates its fault conditions under partial discharge (low-energy discharge) and spark discharge (high-energy discharge), studies the dielectric and gas production characteristics, and explores the applicability of the existing fault diagnosis methods for synthetic esters. The results show that during partial discharge, the dielectric constant and loss of the synthetic ester increase, and the resistivity decreases. With the increase of discharge time, the relative percentage of CO continuously decreases, while that of C 2 H 6 and C 2 H 4 continuously increases. Since the C 2 H 4 content of the synthetic ester is significantly higher than that of the mineral oil, the commonly used diagnostic methods are not suitable for the partial discharge fault diagnosis of the synthetic ester. In spark discharge, the gap distance has little impact on the starting voltage but a great impact on the breakdown time, and the dielectric performance deteriorates seriously. C 2 H 2 is the characteristic gas of the synthetic ester spark discharge, and a large amount is produced, but with the increase of the gap distance, its relative percentage continuously decreases. For the spark discharge fault diagnosis of the synthetic ester, the improved three-ratio method and DUVAL triangle method have certain applicability. Comparing different discharge energies, the increase of the discharge energy aggravates the deterioration of the synthetic ester. Under high-energy discharge, the dielectric constant increases significantly, the hydrocarbons increase rapidly, and the C 2 H 2 content increases sharply. Finally, the Duval triangle was modified according to the gas generation characteristics. This research can provide data support for the application and fault diagnosis of synthetic esters in power transformers.