METHOD FOR TESTING AC DIELECTRIC BREAKDOWN OF POWER CABLE

摘要

PURPOSE:To easily and certainly discover a dielectric breakdown hole by applying AC voltage across a lead and a shield body to generate dielectric breakdown in an insulating body and instantaneously stopping the application of the voltage to form the dielectric breakdown hole in the insulating body. CONSTITUTION:AC voltage is applied across the conductor 11 and shield body 15 of a CV cable 10 to generate dielectric breakdown in an insulating body 13 and the application of the voltage is instantaneously stopped to form a fine dielectric breakdown hole 18 in the insulating body 13 while the state before dielectric breakdown is preserved as much as possible as it is. Next, water 57 being a non-insulating liquid is introduced between the conductor 11 and insulating body of the cable 10 under pressure. The cable 10 whose breakdown hole 18 is filled with the water 57 by this method is cut into two parts and the respective parts are subjected to a megger test. The cut part having the breakdown hole 18 formed thereto lowers in insulation resistance but the other healthy cut part does not lower in insulation resistance. Further, by successively repeating the cutting of the cable and the megger test, the position of the breakdown hole 18 is roughly estimated.