Prevention of Transformer Failure through Continuous Monitoring

A utility decided to monitor the condition of the insulation system of an old transmission transformer. The installed system monitors the absolute values of bushing insulation capacitance and dissipation factor, taking the reference signal from a group of voltage transformers located in the same substation. Partial discharges are measured at the bushing measuring taps and in the ultra-high frequency range with an antenna installed within the transformer tank. The advantages provided by both methods are combined in order to confirm the presence of the partial discharge (PD) activity inside the tank. The system employs advanced techniques of multi-channel and multi-spectral PD sources and noise separation and identification. An acoustic localization of the PD was also undertaken and the…