ITEE Innovation Expo 2008 : Project Details

Investigate optimisation of polarisation measurement time using the Charge Difference Method (CDM)

Power transformers around the world are approaching toward the end of their design life and they are essential components of transmission systems in power industries. Replacement of transformers through their design life is unrealistic because some of them are still in workable condition. Hence the condition monitoring of the transformer is vital for the power industry. Polarization and Depolarization Current method used for assess the oil and paper conductivity which comprise the transformer insulation the oil conductivity is estimated at the beginning stage of the polarization current, while the paper conductivity is estimated at the later stage of the depolarization current and it is taking a longer time (10000 seconds) to obtain accurate paper conductivity. Hence, charge difference method is introduced which is less disturbed by noise and it is able to assess paper insulation of the transformer tested. The purpose of this thesis project is to evaluate the shortest time possible to determine the transformer paper conductivity; using charge difference method. A comparison is also made with the current difference method which is an alternate way of assessing the paper conductivity. The test data is obtained by implementing PDC method on the power transformers.