Growth properties of sulfide trees in cables under dc stress

Investigations on the growth properties of sulfide tree in cable insulation, subjected to dc electric fields, are described in this paper. Measurements of electric strength and conductivity are correlated to tree growth, observed by optical and electron microscopy, during accelerated aging tests performed in sea water with hydrogen sulfide. It is shown that both electric strength and dc conductivity are very sensitive to the length and concentration of sulfide trees, and that the magnitude of the electric field affects tree shape and growth rate significantly.