Study on polarization and depolarization current detection device for XLPE cable

The polarization/depolarization current (PDC) detection device was designed to measure the broad range current from μA to pA level, which was suitable for 10kV XLPE cables ageing test. To achieve wide range of measurement, the ultra-low bias current amplifier and feedback resistances which had different values were used in the I/V conversion circuits. Teflon material was taken to prevent leakage current in the circuit board. Some effective methods (e.g. ultra-high value resistance, electromagnetic shielding, multiple filters, and high precision A/D conversion) were used to improve the accuracy and resolution of the measurement. The verification indicates that the device has a current measuring range of ±20μA, and a resolution of 0.1pA. The device was used to measure the PDC of the aged cable sample.