Flux Based Technique to Identify the Location of Inter Turn Faults in Transformer

  • Swapnil Y. Gadgune
  • Imran S. Mulani
Keywords: Transformer, internal fault, search coil location

Abstract

The internal turn-to-turn faults (TTFs), as a common cause of the transformer failures, result in minor changes on terminal currents/voltages. They maybe undetected by the conventional protective relays. In this study, a simple, sensitive and robust linkage flux based technique is proposed to protect the power transformers against TTFs. In this approach, some separated multi-turn windings as search coils (SCs) have to be wrapped around the transformer core legs to sense the related passing flux. Since passing equal flux through a transformer core leg in normal condition induces equal voltages in the related SCs, variation of the induced voltages indicates the fault occurrence in that phase. Against the traditional differential protection schemes, current transformer error and saturation, tap changer operation, energizing inrush current, over-fluxing etc. cannot impact the proposed technique performance. Therefore, it can be introduced as a comprehensive protection technique for power transformers. It is notable that not only the internal TTFs can be detected by the proposed technique but also other types of internal faults are diagnosable by this technique. For example, the Earth faults near the star point are detectable whenever the star connected winding is grounded solidly. Such faults are similar to TTFs near the star point, and then they are detectable by the proposed technique, as well.

The presented technique can discriminate the external faults from the internal ones, too. When an external fault occurs, transformer winding is shorted entirely. Therefore, the corresponding SCs measure the equal reduced linkage fluxes overall the faulty phase, and accordingly the ΣΔΕ on the faulty phase cannot be activated, as it should be. As a brief review, the ΣΔΕ can detect any event that creates a distortion in the flux symmetricity along each core leg. It senses only the flux uniformity along the core legs and reacts whenever this regularity is distorted.

The proposed technique can be used for all power transformers with different rating voltages and powers. Moreover, type of windings connections cannot impact the performance of the proposed technique, while it is demonstrated on the basis of the flux homogeneity in the healthy transformer core.

References

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Published
2020-03-26
How to Cite
Gadgune, S. Y., & Mulani, I. S. (2020). Flux Based Technique to Identify the Location of Inter Turn Faults in Transformer. Asian Journal For Convergence In Technology (AJCT), 5(3), 87-90. Retrieved from http://asianssr.org/index.php/ajct/article/view/926