In my September 2, 2011 post, I replied to a Connecticut fan that inquired on the prudence of flowing through legacy splices. At the end of that post I promised to explain integrated rehabilitation – the ultimate approach to rehabilitating underground cables. When it comes to rehabilitating aging underground power cables there are basically three tool choices: A good choice, a better choice, and the best choice. The only bad choice is to do nothing at all.
Replacing aging cables and associated components is a good choice. The post replacement reliability is likely to be better than 99%. Most post-replacement reliability issues are likely to be craftsmanship. The dark sides of replacement include its capital inefficiency, its negative environmental impact, and the disruption to electrical customers as heavy equipment moves around their neighborhoods. No matter how the legacy cable was buried (i.e. direct buried, in conduit, single phase or multi-phase) it will require at least twice as much capital to replace as required to rejuvenate. Particularly for direct buried cable, which is typically abandoned in place, all the copper, aluminum, and polymer must be replaced with new natural resources, suffering a considerable carbon footprint.
Rejuvenation is like recycling cable in place and at a fraction of the cost of replacement. Unsustained pressure rejuvenation or UPR, has been practiced for over two decades. Post-injection reliability is on a par with replacement and anticipated life of two decades or more is possible. When splices are encountered, an attempt is made to flow through those splices with varying degrees of success. Some circuit owners have great success; others have dismally low success. On average, about half of the splices encountered support flow. Improved UPR or iUPR was introduced in 2008 by Novinium. Improved UPR eliminates the soak period used in the original UPR approach. Elimination of the soak period improves the safety and the economics of the UPR injection paradigm.
Introduced in 2005, Sustained pressure rejuvenation or SPR enjoys numerous safety and operational advantages over UPR. Most significantly …
1. Exposure to energized components is reduced several-fold from UPR making the process inherently safer.
2. Dielectric properties increase about 87-times faster than with UPR or iUPR. This means even higher post-injection reliability.
3. Even single-section, post-failure injection is authorized to be capitalized by the FERC and RUS.
4. A single visit to a cable segment means minimal disruption to electrical end-users.
With these three tools in our rehabilitation toolbox, Novinium draws the right tool for the job. Because SPR enjoys the greatest capital efficiency and the highest post-rehabilitation reliability, it is applied to as many cables as possible. The vast majority of cables are rehabilitated this way.
Occasionally, a splice, which will support flow, is pinpointed in a location too difficult to excavate. For these cases, iUPR is utilized. In spite of the compromises associated with flowing through splices, iUPR is still more capital efficient than replacement and has a similar post-injection reliability for a couple of decades.
Finally, where there is widespread neutral corrosion or too many splices, the most capital intensive replacement tool is utilized.
The key to the unmatchable economics of the integrated approach is the minimization of replacement. Worldwide there is a single rehabilitation supplier capable of providing the fully integrated rehabilitation approach – Novinium. Novinium founders invented UPR, iUPR, and SPR, so there is nowhere else that circuit owners can access the world’s foremost experts.
Using the right tool for the job,
T. B. Frog