Routine over-voltage testing of high-voltage cables

Routine over-voltage testing by direct current at high voltages is considered as a means of locating and eliminating weaknesses in the insulation of high-voltage cables, which might otherwise develop into breakdowns in service. A series of tests carried out on a cable network operating at 11 kV is described, from the results of which conclusions are drawn as to the lines on which tests should be carried out and the extent to which service breakdowns may be eliminated.