Determination of Water in Transformer by Water Solubility and Percent Moisture by Dry Weight in Comparison with ppm Water Value for Justification Transformer Maintenance

Abstract

The measure of water content is to find water content in transformers. There are many ways that water can occur in the transformers, such as residual moisture in the paper insulation and oils during the manufacturing process, generating from the degradation of transformer paper insulation and oil, ingression into the transformer, etc. The water in the transformer resides in liquid insulation approximately 1% and in the solid paper insulation of roughly 99%. The status of water in oil and water in paper insulation is not stable; water in paper insulation moves into transformer oil and vice versa, depending on loads and temperature. Both waters in oil and water in paper insulation reduce the insulation property of the transformer. This paper aims to present the observations of total water content in the transformer (water in oil and water in paper insulation) compared to the PPM value directly from laboratory testing to understand the severity and manage proper transformer maintenance decisions.