Voltage Rating Of A Three-Core Power Cable From Considerations Of Discharges In Voids

The voltage rating of a three-core belted cable is determined such that it should be above the discharge inception voltage within the cable. The phase voltage is determined as a function of the location of the void within the cable, the diameter of the void, the gas pressure entrained in the void and for spherically and cylindrically shaped voids. It is found that the voltage required to initiate a discharge is a function of the location of the void and it is lowest for voids located in the vicinity of the interface between the conductor and the dielectric. The discharge inception voltage depends on both the dimension and the geometrical shape of the void. The voltage is higher for a spherical than a cylindrical void and decreases with increasing diameter of the void in the range generally found in practical cables.