Resposta em frequência de transformadores de potencial indutivo: uma analise experimental

Abstract

Faced with the growing of electronic components with nonlinear characteristics associated with electrical power systems, its noted the appearance of undesirable harmonics flowing between the busbars, so that the level of harmonic distortion tends to increase. It might compromise the operation of equipment, such as capacitors, electrical machines and transformers. Also, it violates the rules imposed by ANEEL and ONS. Therefore, for the corrections that can mitigate these effects to be taken, it is necessary to get accurate measurements of harmonics levels. However, in high voltages, transductors of potential are typically used to connect quality analyzers. That’s when measurement mistakes are found. In high frequencies, potential transformers do not keep their unitary transformation ratio, as it happens in the fundamental frequency. It leads to mistakes in the process of transformation of the primary to secondary voltage. Therefore, the objective of this study is to find the frequency response curve of several kinds of the potential transformers, in order to reduce misinterpretation about the distortions levels. For this purpose, the Frequency Response Analysis (FRA) was used to find the behavior of the transductors in high frequency, leading to reliable results. Finally, a frequency response analysis of the commercial equipment in terms of its practical tests is presented, as well as the associated mistakes.