Improving Transformer Differential Protection Dependability for Low-current Turn-to-turn Faults

G. Díaz, A. Barbón, and J. Gómez-Aleixandre (Spain)


Turn fault, transformer, symmetrical components, model


This paper presents a new method to evaluate the exis tence of an internal fault of type turn-to-turn in a trans former. A self-defined transformer model is presented, as well as the simulations conducted. The transformer model has been pre-validated by means of the comparison of its performance with that of another model, the latter solved by means of the 2D finite element analysis. The simulations results show that the currents can be ana lyzed through the resolution into their symmetrical com ponents. Based on it, a theoretical approach is explained to describe the transformer performance. Moreover, an explanation about the load power factor and the fault lo cation is explained. The results obtained are then applied to a 20/ 0.38 kV distribution transformer, which was completely disassembled and arranged to develop internal faults. Results agree with the proposed evaluation method.

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