Abstract
Frequency Response Analysis (FRA) is an Off-line condition monitoring technique for the transformers and is successful, in diagnosing mechanical faults and inter-turn short-circuits. Only limited literature is available for On-line FRA works, and the effect of the transformer’s load on the fault diagnosing capability of FRA has not yet been analysed. Motivated by this research gap, an experimental investigation was done to analyze the effect of load on IFRA based inter-turn short-circuit diagnosis. A single-phase 1 kVA, 240V/240 V transformer supplying R and R-L loads and a three-phase 5 kVA, 440 V/440 V transformer supplying an induction motor at various load levels were tested. Inter-turn short-circuits were emulated in their windings and, the effectiveness of IFRA in diagnosing the same was investigated. Comparisons were made between the frequency response of the loaded transformers in their healthier conditions and emulated fault conditions, based on the transfer function plots and the statistical parameters. Investigations reveal that the loads alter the useful spectrum of IFRA. The frequency response of the healthier transformer itself varies based on the transformer’s load and necessitates a careful focus on the sensitive frequency spectra for effective inter-turn short-circuit diagnosis in loaded transformers.
Highlights
Condition monitoring of transformer and fault diagnosis at earlier stages will reduce downtime and maintenance expenditure, thereby ensuring the reliability of the power system
Two types of comparisons were made to analyse the influence of the transformer’s load on its frequency response: (1) Comparisons in terms of the EEV-TF plots of different cases and (2) Comparisons in terms of statistical parameters extracted from the End Voltage Transfer Function (EEV TF) magnitudes, on sub-band basis [19]–[21]
An experimental investigation was carried out to analyze the effectiveness of Impulse Frequency Response Analysis (IFRA) in diagnosing inter-turn short-circuits within transformers under different load conditions
Summary
Condition monitoring of transformer and fault diagnosis at earlier stages will reduce downtime and maintenance expenditure, thereby ensuring the reliability of the power system. Testing techniques like FRA, DGA, PDC have gained importance and focus and has been an area of attraction among researchers globally [1], [2]. Techniques like DGA and PDC focus on the dielectric behaviour whereas, FRA addresses issues like winding deformation, displacement; both axial and radial [3]. Researchers have identified that the radial deformation of winding, axial winding elongation, overall-bulk and localised movements and short-circuits are the frequent faults of the transformer windings. Winding deformations can occur due to sudden surges in electrical loading pattern which, if unnoticed, will result in severe damages.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
