Failure investigation of buffer layers in high-voltage XLPE cables

•A new-type failure of HV XLPE cables have occurred in recent years.•Lots of white powder and ablated traces appeared in the buffer layers.•Standard failure analysis methods are conducted, including SEM, EDAX, and XPS.•The appearance of white powder and electrochemical corrosion are analyzed.•Causes of the buffer layer failure are explained and measures are recommended.