Evaluation of Moisture Content in Paper-oil of Aged Power Transformer Using RVM

Abstract

The many diagnostic tools (like Conventional oil test, DGA, DLA and RVM) are available.. From the test results, it is observed that the transformer which has very good result from these techniques and even minimum moisture content in the winding may / will have very poor mechanical integrity. Winding cellulose paper may be aged to such an extent (assessed from DP) that may sudden force or transient may result in failure. DP cannot be conducted regularly to ascertain mechanical integrity of the winding paper. Furan analysis is a substitute for DP. But most of time, Furans are not detected and there is no universal correlation available for DP and Furan.. Both, the moisture content and ageing of paper influences furan. Frequency response analysis gives the information regarding the movement of winding but does not give much, information above mechanical integrity of winding which is essential for transformer reliability. In this paper, an approach has been made to compare the moisture content in the winding from RVM and estimated from oil ppm (using Norris diagram) and estimated from winding DLA (based on Gussenbaner’s relationship)