Measurement and location of dielectric anomalies in field aged XLPE cables

In order to adequately assess the condition of field aged XLPE cable it is necessary to select diagnostic test methods which are sensitive to each type of detection. The paper reports the results of a field test program to evaluate the condition of a number of aged XLPE cables operating at 12 kV and 25 kV line-to-line. Promising test methods included time domain reflectometry to detect and locate PD sources as well as other anomalies in the dielectric. These sites may be temporarily enhanced as a result of selected overpotential tests at a moderate level. Subsequent dissection has revealed extensive water trees and incipient failures in the detected locations.<
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