Zhiqin Ma

TL;DR: In this article, a comparative study of physicochemical, ac breakdown strength and thermal stability behavior of BIOTEMP natural ester/pressboard insulation and Karamay 25# naphthenic mineral oil/press board insulation after long term thermal ageing was conducted.

TL;DR: In this paper, a new method for assessing the ageing condition of the oil-paper insulation in terms of the depolarization charge quantity was proposed, which can also be used to assess the condition of new insulation system using natural ester in transformers accurately.

TL;DR: In this paper, a method for evaluating the aging degree of main insulation of a transformer is proposed, which considers the influence of multiple factors such as measuring temperature, a main insulation structure, and oil conductivity, and has wide applicability to an oil-immersed transformer; the defects in a traditional chemical and electric method are compensated; the moisture content of the main insulation, and meanwhile the aging state of the insulation can be evaluated; and moreover the method can be used for on-site diagnosis directly, and have the advantages of lossless, convenience, transplantation and the

TL;DR: In this article, the authors show that both polarization and depolarization current increase with temperature and an inflection point appears in the depolarisation current when moisture content is lower, and the time of inflection points shifts to lower with temperature increased.

TL;DR: In this article, the authors measured and analyzed the temperature dielectric spectrum (TDS) characteristics of the transformer oil-paper insulation to evaluate the state of the vegetable oil paper insulation system.