A method to accelerate FDS measurement using logarithmic chirp excitation voltage

This paper reports an application of logarithmic chirp waveform as a broadband excitation to reduce Frequency Domain Spectroscopy (FDS) measurement time for condition monitoring of oil paper insulation of transformer. In conventional FDS measurement, the insulation under test is subjected to sinusoidal excitation voltage over the frequency range 1kHz-0.1mHz, for a period of two cycles. Due to frequency sweep down to 0.1mHz, conventional FDS measurement takes significantly longer time to perform at site, which is a practical problem. In an attempt to solve this problem, a different approach is adopted in this work which is capable of reducing FDS measurement time appreciably. Instead of applying conventional sinusoidal excitation, a broadband excitation voltage in the form of logarithmic chirp waveform band limited from 1Hz-0.1mHz is used to conduct FDS measurement in the laboratory. The method is experimentally verified on two real life transformers, which validates the practical applicability of the proposed technique.