Innovative application of Frequency Response Analysis for Partial Discharge measurement

Measuring partial discharge on transformers and rotating machines requires knowledge of the frequency characteristics of the the object impedance. This allows assessing capacitive or transmission line behavior and localizing resonances. Impedance measurement is a helpful tool to correctly select the coupling capacitor and measuring impedance for optimal sensitivity. In this paper, a method of impedance measurement is presented based on the same frequency response Analysis (FRA) equipment used for transformers. The typical decrease with frequency of the equivalent capacitance of tranfsformers and the Transmission line behavior of rotating machines are investigated both with simulations and measurements. The impedance measurement gives insight to the electrical behavior of the test object,…