Rahimpour - University of Tehran Iran، University of Stuttgart Germany
Christian - University of Stuttgart Germany
Feser - University of Stuttgart Germany
Mohseni - University of Tehran Iran

The application of the transfer function is discussed at present as a method for diagnoses and on-site monitoring of power transformers with regard to mechanical damages of the winding. In order to be able to evaluate the measurements, the correlation between the characteristics of transfer functions and possible damages must be known. Real failures in operation do not occur with sufficient frequency, in order to be able to compile these empirically. Apart from the experimental damaging of test windings, these correlations can also be investigated more in dept with mathematical computer models. These facts lead to the development of a computer model which simulates results of executed experiments as exactly as possible. Based on this model, winding damages can also be simulated. Using this model one can investigate the correlation between modifications in the structure of the winding (turn short circuit, mechanical shift etc..) and the transfer function characteristic of the winding at high frequencies. The modeling was done for a noninterleaved double disk winding of small power (1.2 MVA) and the effect of locus-dependent turn short circuits on the transfer function was examined in more detail. The simulation outcomes are compared to appropriate experimental results.

Transformer, High frequency Model, Monitoring, Transfer Function