Method for characterization of insulation state of oiled paper insulated cable in high voltage power cable for determining ageing state, involves calculating p-factor from measured return voltage curves

摘要

The method involves calculating a p-factor as a quotient of a maximum value of a return voltage curve and a product of an initial slope of the curve and a time point at which the maximum value of the return voltage curve is attained, where the measured return voltage curve includes the capacitances of an oiled paper insulated cable line and a crosslinked polyethylene insulated cable line. An influence on measurement values of a voltage measuring device is corrected based on effective internal resistances of the voltage measuring device.