| The introduction of digital recording and signal processing techniques permitted the development of a measuring system showing the transient property of transformers and forecasting the voltage distribution in the windings for any transient overvoltage originating from the network or the test lab. The present thesis explains such a system called MACT.;Generally, in the transformer design process, a modeling software is used to calculate the transformer transient behavior. The second part of the thesis compares, for a given transformer, the results of the model with the results provided by the MACT tool. Various discrepancies prove the weakness of the model and therefore bear out the implementation of the tool.;As an example, the third part consists of the evaluation of the transformer insulation safety margin. First, a series of measurements provides the HV winding transient property. The typical lightning impulse voltage distribution along the winding was then calculated. Next, the maximum dielectric stress and its location were determined. The stress was compared to a reference curve establishing the maximum allowed.;ABB plant in Varennes has integrated the MACT tool in the transformer building inspection process. The forth part explains the usefulness of the MACT tool. It was also used to study a EHV transformer's winding penetration of transient overvoltages captured on Hydro-Quebec network.;In conclusion, a new project using this measuring and analyzing tool is suggested. It consists of the assessment of the irrelevance of the test waveshapes. The transient distribution obtained from a measured transformer would be compared with the transient distribution of typical waveshapes captured on the network. (Abstract shortened by UMI.)... |
