Hot-Line XLPE Cable Insulation Monitoring Based on Quick Positive and Negative DC Superposition Method

摘要

According to the feature of DC superposition theory which is applied widely in monitoring the insulation condition of power cable with cross-linked polyethylene insulation (XLPE), such as high precision but time-consuming, so a quick positive and negative DC superposition monitoring method is presented in this paper. In which the Positive and negative DC voltages are injected to detection circuit respectively, and the steady voltages of the two conditions mentioned above are calculated from the transient voltages of sampling resistance. Considering the algebraic average of positive and negative steady voltages as finally steady voltage, so the value of insulation resistance for XLPE power cable is obtained. The proposed method not only has avoided infection in measuring precision resulted from water treeing, but also taken into account distributing capacitance; the monitoring time has been decreased. WINBOND W78E58B has been used in signal processing and the experiment results have affirmed the availability.