Influence of XLPE-covered cables on the impulse withstand voltage of a single-phase structure used in compact distribution lines

This paper investigates the influence of XLPE-covered cables on the impulse withstand voltage of a typical structure used in single-phase compact distribution lines in Brazil. For comparison purposes, two different procedures are adopted for estimating the impulse withstand voltage of this structure under standard positive lightning impulses. One considers a bare cable and the other assumes a XPLE-covered cable. For the impulse withstand analysis considering the bare cable, the up-and-down method is used for determining the critical flashover overvoltage (CFO) of the structure. The corresponding Vxt curve is also determined using the standard procedures. For the impulse withstand analysis considering the XPLE-covered cable, the breakdown voltage was determined in two different laboratory tests, the first one considering a brand new cable and the second one considering a punctured cable. Both tests were performed for two different cable manufacturers.