Improved Technique for Fault Detection Sensitivity in Transformer Maintenance Test

Transformer windings might be shifted because of short-circuit current, aging or impact during transportation. The shift modifies the dielectric space between the layers of the windings and may cause an insulation breakdown. Since transformers are expensive to replace, it is vital that their condition are determined accurately without having to dismantle the apparatus to inspect it visually. Generally, transformers test is performed for maintenance purposes, by either low voltage impulse (LVI) test or frequency response analysis (SFRA) test. Both methods have been adopted within the industrial applications. Nonetheless, they have drawbacks, including limited frequencies range for LVI test and time-consuming measurements for SFRA test. To obtain better signature analysis and to increase the detection sensitivity in the transformer maintenance test, this paper suggests a new input signal using a random pulse sequence (RPS) in the transfer function analysis. The results of RPS test are compared against the LVI and SFRA tests to complete the assessments.