Comparison of Voltage Response and Return Voltage Measurements of a Transformer Insulation Model

Summary

In mid 1960s, Endre Németh brought on the idea of measurement of return voltage as a diagnostic technique of the insulation of high voltage equipment. From this idea, two diagnostic methods have been developed, namely the Return Voltage Measurement (RVM) and the Voltage Response (VR) method. The recent development of the VR method – by changing of shorting times – enables to investigate the polarisation processes more precisely, moreover by a simple iteration method the parameters of the equivalent circuit of an insulation can be calculated. In this study, parallel RVM and VR measurements were executed on a transformer insulation model at different temperatures. From the results of the VR measurement the distributions of the intensities of polarisation processes were calculated and the results were compared to the polarisation spectrum provided by RVM method. The results were provided by both measurement method highly dependent upon the geometry of the insulation system because the tested insulation has multilayered arrangement, which is built up from oil, paper and prespane. Therefore the temperature dependence of the results were also sensitive to the connection. The results of newly developed method show that the transformer insulation can be described by an equivalent circuit, which contains only five Debye elements.

Additional informations

Authors

Tamus Zoltán Ádám, Szirmai Ágnes, Németh Bálint