Effects of Impulse Waveform Parameters on the Breakdown Characteristics of Nano-TiO2 Modified Transformer Oil

Statistical results have shown that the waveforms of impulses invading power transformers differ from those of the standard impulse voltage recommended by the IEC Standard. However, the effect of such differences on the modification effect of nano-modified transformer oil has rarely been studied. The present work therefore experimentally investigated the effects of impulse waveform parameters on the breakdown characteristics of nano-TiO2 modified transformer oil (NMTO). We determined the breakdown characteristics of NMTO with different nano-particle concentrations, and compared the breakdown characteristics under both standard impulse voltage and non-standard impulse voltage. Specifically, the influence of the wave front time and wave tail time of the applied voltage on the breakdown characteristics of NMTO were experimentally identified. Finally, mechanisms of observed phenomena were analyzed. Test results indicate that both the waveform parameters and polarity have important effects on the modification effect of NMTO. Such effects are attributed to the migration of positive particles and charged nanoparticles.