Method of testing the voltage withstand ability of a high voltage d-c cable at a voltage higher than its normal operating voltage while carrying current

摘要

A high voltage d-c cable is tested by first disconnecting the normally- grounded sheath of the cable from ground and providing insulation between the sheath and ground. The sheath is then biased to a predetermined bias voltage that is of an opposite polarity with respect to ground as the normal operating voltage of the cable conductor. The conductor is then energized with current and test voltage derived from its normal source. This test voltage is of the same polarity with respect to ground as the normal operating voltage of the cable conductor and of a magnitude approximating said normal operating voltage, whereby the difference between said test voltage and said bias voltage is applied to the cable insulation between the cable conductor and sheath.