Sensitivity of leakage inductance for detecting winding movements in transformers

Abstract:

Leakage inductance of transformer windings is widely used as a health indicator especially for detecting winding anomalies. This test is also routinely carried out before and after short-circuit withstand test which is a part of factory acceptance test. Change in leakage inductance can possibly reveal damages in the winding assembly. Some research efforts report that leakage inductance captures structural alteration in the winding, viz., winding movement. However, diagnosing the extent of damage is not, in general, possible from the deviation in leakage inductance. Asymmetry introduced by the movement of windings makes a transformer vulnerable to short-circuit forces and therefore diagnosing the severity of such movements is crucial. This paper analyzes the change in leakage inductance for various degrees of radial and axial movements of windings. The investigation was carried out using Finite Element Method on a typical power transformer design. It was found that leakage inductance is affected by large movements in the axial direction while it was found to be practically insensitive to small axial movements. Radial movements were found to yield no significant change in leakage inductance irrespective of its severity. Simulations performed using Ansys Maxwell are reported and the observations are explained using the behavior of computed magnetic fields.

Año de publicación:

2019

Keywords:

Fuente:

scopus