Chemical treatment of URD cables

Cable rejuvenation fluids have been safely injected into cables for more than 20 years. This process increases the dielectric strength of the cable and removes the water trees plaguing older polyethylene cables. The increased dielectric strength and the removal of water trees leads to a considerable increase in the remaining life of the cable. This paper first looks at the early stages of the injection process. A look at how long it takes the fluid to move from the conductor into the PE insulation is calculated. Next, the basic chemistry of the water tree filling and fluid oligomerization is addressed. The resultant fluid is then tracked by diffusion in the polyethylene to give an estimate of how long the fluid stays in the insulation. This can give a cable owner comfort in the length of time the cable should maintain in reliable service. This cable is looked at from the start of injection to the end of its useful life.