Investigations on liquid insulation system and enhancement of their characteristics in power transformer

Abstract

The condition monitoring of the sensitive equipments in the Power system are essential to maintain continuous power supply. Power transformer is one of the most important equipments in the system to be monitored very closely. Systems abnormalities like excess loading, switching and ambient conditions are responsible for its accelerated ageing and sudden failure. Insulation plays a sensible role in determining the life time of transformers. To determine the performance of transformer, it is necessary to have investigations on ageing of transformer oil due to thermal degradation. The behavior of various critical parameters of transformer oil is interpreted with a view to enhance its life time. The diagnostics of the critical parameters for the defined ranges of ageing of transformer oil attempts to determine the level of insulation and serve to ensure its efficient operation. In the present work an effort has been made to analyze various critical parameters like acidity, Breakdown Voltage (BDV), viscosity, volume resistivity, loss tangent, dielectric constant and spectral characteristics for different range of thermal degradation of transformer oil with various compositions of materials like pressboard and Kraft paper. As an initiative exclusive Thermal-Ultraviolet analysis has been carried out to investigate the spectral characteristics of transformer oil. Solid insulation like Kraft paper, press board on degradation process generates furanic compounds such as 5-Methyl Furan, 2-Acetyl Furan, 2-Hydroxy Methyl Furan and 2-Furaldehyde. Traditionally the presence of furanic compounds in transformer oil is determined using High Performance Liquid Chromatography (HPLC). An effort has been made to estimate the presence of furanic derivatives using, a low cost technique, that is UV-Visible light absorbance property of furanic compounds. Degree of polymerization of insulation paper and remaining life time of transformer has been examined.