This paper presents a new data processing method of partial discharge (PD) pulse in AC withstand voltage test based on rectangular time-frequency filter (RTFF). It is that according to the requirements of AC withstand voltage test using the ultra wide-band PD detection system, the two-dimensional time-frequency window (2D-TFW) mainly resorting to discrete Fourier transform (DFT) to dynamically display the PD parameters under the current withstand voltage working condition is designed and used, including pulse waveforms in time domain and frequency domain, peak phase or time sequence, number of pulses, maximum value of pulses, etc. Then, the tester manually sets the RTFFs on the 2D-TFW, which is also can be called the joined time-frequency windowing method to dynamically display the PD parameters associated with the RTFF under the current withstand voltage condition, so as to realize the real-time anti-interference and pulse source separation. All pulse waveform phase or time sequences under working conditions before and after withstand voltage are stored. So, in addition to judge whether the insulation withstand of the current test object meeting the requirements of PD test in real time, playback analysis can also be carried out after the test using the saved pulse waveform phase or time sequence data file. 

partial discharge deteciton,AC voltage withstand test,rectangular time-frequency filter,ultar wide-band