Assessment of Transformer Cellulose Insulation Life Expectancy Based on Oil Furan Analysis (Case Study: South African Transformers)

Abstract

A R T I C L E I N F O A B S T R A C T Article history: Received: 04 Ju ne, 2021 Accepted: 21 August, 2021 Online: 13 November, 2021 The agein g of oil-immersed power transformers triggers several defects and dama ges in the insulating materials, particularly in the cellulose insulat ion. The decomposition of the cellulose paper produces dissolved gases into the insulating oil, in which the Dissolved Gas Analysis (DGA) of the oil samples can provide insights to incipient faults sustained by the transformer as well as the status of the insulation. The conditio n of the cellulose insulation can be established by the measurement of the Degree of Polymerization (DP). In some instances, when the DP is intricate to measure, the estimation can be realized by collating info rmation with respect to oil Furan analysis (2-furfuraldehyde (2FAL)). In this work, regression analysis based on 120 transformer oil samples is developed to establish new formulae by generating an analogy betwe en the DP and 2FAL to indicate the status of the cellulose insulation and percentage of remnant life expectancy. In present study, five diff erent transformers are tested using the proposed formulae to compute t he DP based on the 2FAL concentrations. The results, are compared with measurement results and four other existing models. The results indic ate an error of estimate of less than 2% and 1% against the measured D P.