Oscillatory wave cable partial discharge（PD） test is a new method for cable defects detecting. The quality of the PD signal collected is closely related to the impedance detection. The traditional RC-type detection impedance cannot take into account the energy of PD pulse detected and its attenuation effect on low frequency test voltage. In order to improve the performance of the detection impedance

a kind of π-type detection impedance for oscillatory wave cable PD test is presented. Theoretical analysis and experimental results show that the π-type detection impedance has a better attenuation effect on low frequency test voltage while keeping a high output pulse energy. In addition

there is a good linear relationship between the input and output signals. In the application of cable PD location under oscillating wave

this detection impedance can be used to detect the PD signal and its reflected waves effectively

and to locate the cable fault accurately. Therefore

the π-type detection impedance has broad application prospects in the PD test for high-voltage and long-distance cables.