Gas-in-oil criteria for the monitoring of self-contained oil-filled power cables

Abstract

Dissolved gas analysis (DGA) initially developed for the monitoring of transformers was recently introduced for in-service diagnostics of power cables. Criteria successfully developed for transformers are not readily applicable to cables because of significant differences in the design and operating characteristics of both systems. The paper presents the development of DGA diagnostic criteria for the maintenance of Hydro-Quebec's power cable network. The diagnostic of a given cable circuit is based on the voltage rating, the individual gas concentration levels, the key gas ratios, the gas formation trends, the years in service, and the load. A new graphical representation ofthe IEC 599 method for the interpretation of gas ratios was developed in view of its application to power cable diagnostic. This new method, also applicable to transformers, solves most of the undetermined diagnostics given by the IEC method. The whole DGA diagnostic procedure logic is coded in an expert system shell automating the final diagnostic on the condition of the cable insulation.

Ferroelectret-based Hydrophone Employed in Oil Identification—A Machine Learning Approach

“…Dissolved Gas Analysis (DGA) is the most used technique to monitor the performance of power transformers [18,20,25,26], and other electrical equipment containing oil. Using the DGA, it is possible to assess the operating condition of the equipment's insulation since this technique is able to identify various types of gases, thus allowing the diagnosis of different types of failures.…”

Metodologia acústica para análise de óleo de transformador por sensores piezoelétricos

“…A taxa de aumento da acidez de um óleo em serviço é um indicador da taxa de envelhecimento do óleo(ABNT, 2009(ABNT, , 2017.ABNT, 1991ABNT, , 2017WANG;VANDERMAAR;SRIVASTAVA, 2002, SUWANASRI et al 2009. descoberta de falhas incipientes na isolação óleo/papel pelo método de DGA é fundamentado no fato de que a quebra da isolação líquida e sólida, sob condições térmicas e elétricas anormais, fornece uma variedade de substâncias voláteis e não voláteis resultantes da degradação do material isolante, que podem evoluir a falhas nos equipamentos(COURDEC;BOURASSA;MUIRAS, 1996).Os gases recorrentes de uma falha são produzidos pela deterioração do óleo do transformador e dos materiais isolantes tais como o papel e o papelão de isolação do núcleo. A taxa da degradação da celulose e do óleo aumenta significativamente com a presença de uma falha dentro do transformador.…”