The main factors influencing the gas preservation condition includes the fault amplitude, fault fragmented intervals, fault surface dip, and the position of fracture cavity system in the faulted zone.

In a drive system of power transistor inverter-motor, not only can it be used in fine control of motor current waveform, phase, amplitude and frequency, but can also be used to sense, fault current.

Because complex wavelet transforms can exactly identify amplitude and phase information in signal to be dealt with, they are suitable for detection of fault signals in power system.