Investigation of Polarization/ depolarization Current Measurment of different Operating Temperatures

Student: Li Li Tan

Supervisor: Tapan Saha

Category: Engineering Thesis Project - Power

Trouble free transformers play an important role in the electricity industry. It is crucial to ensure that transformers operate efficiently due to the increasing demand of electric energy. Condition monitoring of the insulation of transformers is an important issue since many transformers in electrical industries around the world are approaching the end of their design life. The degradation of transformer insulation is one of the major causes of transformer breakdown. Condition monitoring can be utilized to attempt the prediction of the insulation condition and the remaining lifetime of a transformer. One of the non-destructive monitoring methods is the Interfacial Polarization Spectra (IPS) measurement by Recovery Voltage Measurement (RVM) and Polarization and Depolarization Current Measurements (PDC). The results of both the RV and PDC measurements are largely influenced by environmental conditions, such as the temperature. The main objective of this thesis project is to investigate the recovery voltage and the polarization and depolarization of current measurements at different operating ranges of temperature. Experiments will be done in the lab on a model transformer with dielectric temperature variations. The reason that we do this project was because we wanted to investigate the temperature effect on the characteristic of the transformer oil-paper insulation. The sharing of moisture between the oil and paper at different temperatures is believed to affect the dielectric response measurement. Efforts will be done to identify the effects of temperature on dielectric response measurements of oil-paper insulation system and correlating it with basic insulation properties like the capacitance and conductivity. The effect of temperature on the parameters of a mathematical equivalent model of the transformer insulation structure will also be studies.

Thesis Document (PDF)