Estimation of the model parameters in equivalent circuit models of potential transformers

In this paper equivalent circuit models of potential transformers with model parameters determined by three different estimation methods are set up. The objective is to compare the complexity and the accuracy of the three methods. The model parameters in the first model are determined by measurements of the open-circuit and short-circuit impedance as function of the frequency and by measurements of the voltage ratio at different loads. From the open-circuit impedance measured by a pseudo random binary sequence signal, the parameters in the second model are found. In the third model the parameters are determined from a frequency sweep of the open-circuit and short-circuit impedances. All three methods describe the frequency spectrum from 100 Hz to 1 MHz. The models and the methods to find the model parameters are compared and verified by measurements on a commercial potential transformer.