The pulse voltage method is an effective method for detecting inter-turn insulation faults in aircore reactors

but it is difficult to identify fault features in the time domain detection waveform. In this paper

a method to identify faults by using its FFT waveform characteristics is proposed. The finite element method is used to calculate the variation rules of inductance of each of layer and total inductance of the coil group of no-fault of coil group in case of fault at different positions of air core reactor. To add pulse oscillation circuit to the coil group model to transform the time domain waveform of voltage on both ends of reactor into frequency domain waveform by way of FFT. The FFT waveform variation feature of different fault locations are compared

thinking that the variation of the attenuation resonant frequency of FFT waveform of air core reactor at different fault positions is due to the variation of inductance

which provides mathematical support for the frequency domain fault criterion. Taking the frequency corresponding to the peak point of the FFT waveform of the faulty coil group as the criterion

a method for judging the fault and the degree of fault of the reactor based on the characteristics of the FFT waveform is proposed

and verified by actual example. The results obtained further expand the effectiveness and accuracy of the pulse voltage method for detecting the turn-to-turn short-circuit faults of air-core reactors

and provide method guidance for further accurately determining the turn-to-turn short-circuit defects of air-core reactors.