Instrument transformers: A different approach to their modeling

As well known, the availability of an advanced and reliable model describing the real behavior of a physical device may strongly simplify the measurement activities devoted to its characterization. A model driven approach can meaningfully reduce the amount and the complexity of the required tests. This is very important when in field experimental activities are required. A typical example of this situation is the metrological assessment of the instrument transformer (IT) for medium and high voltage applications. The aim of this paper is to present a different approach to the instrument transformer modeling. This proposal leads to an analysis of the instrument transformer that is independent by the waveform shape of the voltage applied to its primary and simply based on the measurement of the input and output signals. In this paper an experimental procedure for the identification of the model parameters of a voltage IT (VT) at the AC-mains frequency is presented and discussed. Finally, the proposed model has been simulated by using the parameters experimentally evaluated. The simulation results have been compared with those obtained through a conventional calibration procedure.