DETERMINATION OF ACIDITY IN ACCELERATED AGED INSULATING PAPER

• Main Author: adiati, Wind
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/39541
• Institution: Institut Teknologi Bandung

Power transformer performance is very dependent on its insulation system condition. Due to the constant load of electrical, mechanical and thermal influences, the insulation is exposed to a continuous aging process. Power transformer oils are oxidized under the effect of excessive temperature and oxygen, this oxidation process will increase the acid number of oil-paper insulation. The acid produced from the hydrolysis process in oil insulation will then move towards paper insulation. Furthermore, an increase in the acidity will break the chain of paper cellulose molecules and eventually causes the cellulose to lose its mechanical and dielectric strength. At the previous time, the acidity number of insulating paper is assumed to be represented by the acidity number of insulating oil, but recent experiment where found that the concentration of water soluble acid can be much higher in the paper than in the oil. Up to now there is no international standard that regulate the acidity measurement of insulating paper, therefore the acidity measurement procedure of paper insulation is required. This research focus on investigating the appropriate methods and procedures to measuring the acidity of paper insulation. The insulating paper tested are impregnated with two different types of oils; the insulating oil is uninhibited (Diala S2 ZU-I) and Gas-to-Liquid (Diala S4 ZX-I). To simulate paper on the aging time, the samples are threated to aged thermally accelerated, an isolation oil-paper model is made to record the aging stages of the paper-oil insulation in an open system, the aging was carried out at a temperature of 130 °C and pressure 0.1 mbar in a heating cabinet for specified time. The research conduct by immersed the insulation paper with pure water in a specific ratio of mass and particular immersion duration; the extract then partially taken to measure it is acidity number using acid-base titration. Nine different methods with different parameter selection that influence the measurement, such as the pretreatment of the paper, mass ratio between solvent and paper sample, paper sample crush process, filtering process, titrated material and extraction mass use for titration are to be investigated. Through this research it is found that the most consistent method to determine the acid number in the paper sample is obtain by dissolving 2 gr of paper sample with 50 gr pure water that put into 50 ml tightly sealed glass bottle, stand the mixture for 5 hours with 25? C storage temperature and continue with acid-base titration of 7 gr paper extract based on IEC 62021. This recommended method will then be used to measure the acidity of the insulation paper impregnated with uninhibited oil (Diala S2 ZU-I) and Gas-to-Liquid oil (Diala S4 ZX-I), and then an analysis of the relationship between the acidity of oil and paper insulation is carried out.