Broadband impedance spectrum detection of buffer layer defects in 110 kV crosslinked polyethylene cable with corrugated aluminium sheath

The buffer layer defects of high‐voltage crosslinked polyethylene(XLPE)cable occur frequently,which makes the detection method become the focus to be studied.Here,the broadband impedance detection technology for the buffer layer defects of high‐voltage XLPE cables with corrugated aluminium sheath is investigated.There are nine cable samples,including new and defective ones.Some of the defective cables are artificial,and the other is retired cables.The influence of wiring mode,the circumferential relative position of electrodes,cable length,artificial white powder,artificial damp,and retired defective cables on the impedance spectrum is studied.It is found that the wiring mode of the insulation shield/aluminium sheath at the end of the cable can effectively detect the buffer layer defects.And the broadband impedance amplitude spectrum of the buffer layer in defective cable,measuring at various circumferential relative positions,is obviously different.When there are white powders,air gaps,or ablation in the buffer layer,the broadband impedance spectrum(BIS)will increase by several times.When the buffer layer is damped,the BIS will reduce.The research here provides theoretical support and technical methods for the buffer layer defects of XLPE cable with corrugated aluminium sheath.