Using impulse with appropriate repetition frequency in IFRA test to diagnosis winding deformation in transformer

Abstract

Frequency response analysis (FRA) is a regular method to detect winding faults in transformer. According to the kind of excitation source, it can be divided into two categories that are impulse frequency response analysis (IFRA) and sweep frequency response analysis (SFRA). Compared with SFRA, IFRA use less time during test and can reach higher frequency domain it's about 10MHz, with SFRA usually up to 1MHz only. However, it has been discovered that the test result of IFRA can be heavily influenced by the repetition frequency of input impulse. In addition, frequency resolution of the test result also need to be considered. In this regard, at first, the impact of repetition frequency is discussed. Then, experiments using input impulse with different repetition frequency are carried out on a 10kV/400V oil-immersed transformer and compared with the test result of SFRA, which can be regard as an accurate reference.