Analysis of the Sensitivity of the No-Load Current Measuring to Detect Short Circuits Between Transformer Winding Turns

Short circuits between winding turns are one of the most common and potentially destructive electrical faults in transformers. This paper analyzes the sensitivity of magnitude changes of the harmonic components in the transformer no-load current to detect turn-to-turn faults. Simulations were used to evaluate the technical feasibility of the proposed test in a singlephase high-power transformer and a three-phase low power transformer. Additionally, in the case of the three-phase transformer, measurements were made experimentally, applying turn-to-turn faults in the winding of one of the phases and analyzing their harmonic content. Finally, it is shown how the reduction in the ratio between the third harmonic and the fundamental component magnitudes is a viable indicator to detect incipient insulation faults between turns.