Effect of Cable Restoration Fluid on Inhibiting Water Tree Initiation

Abstract

Silicone fluid has been applied in cable rejuvenation for decades to “cure” existing water trees. However, whether it inhibits future water tree initiation is not known. An electrical aging test has been carried out at 5 kV/mm (127 V/mil) based on a sample which includes semicon electrodes on both sides of the insulation. Samples were tested untreated, treated prior to the test, and treated at the midpoint of the test (3500 h). The results suggest that treatment reduces water tree initiation by a factor of 25 for bow-tie and 100 for vented water trees for the samples treated prior to aging. In the case of samples treated at the mid-point of the test, both bow-tie and vented water tree density are reduced by an order of magnitude relative to the density present at the time of treatment.