The defects of the buffer layer will bring hidden danger to the operation of cable

by which the cable breakdown will seriously endanger safe and stable operation of power system. For studying the defect mechanism of discharge by the white spot in the cable layer

the white spot defect experiment is performed by the artificial simulation

the resistance of the buffer layer with white spot defect is measured and the influence of the white spot on the electrical connection of the buffer layer is studied. Moreover

the equivalent circuit model of cable considering the white spot is set up

the potential variation of the buffer layer in case of fault is simulated and calculated. The discharge simulation experimental platform of the buffer layer is set up for detection of discharge signal. The study results show that the resistance between the buffer layer is increased by more than 10 times after the white spot defect is contained in the trough of each aluminum sheath of the cable

which seriously damages the electrical connection of the buffer layer

leads to the increase of the electric potential of the buffer layer and the increase of the electric field intensity between the buffer layer

thus causing the discharge and damaging the buffer layer.