Cables, reliability and rejuvenation
Editor-in-chief Kathleen Wolf Davis sent me a few questions on our work with cable rejuvenation. Here's a little bit about the project we're working on in that arena.
Davis: Can you tell me about your utility? How many customers you serve, location, physical environment, etc?
We are an electric cooperative with a service territory of 5,000 square miles mostly east of Colorado Springs, Colorado. With over 43,000 members and 52,000 meters we provide electric service to predominantly residential accounts. MVEA incorporated in 1941 as a not-for-profit electric cooperative owned and run by the members it serves. A board of directors from seven different geographic districts and elected by the members, governs our business. MVEA’s headquarters are in Limon, Colorado, with a large operations center located in Falcon, just east of Colorado Springs. Our region is known to have a semi-arid climate with relatively mild temperatures. We are at the edge of the southern Rocky Mountains, so our ground does have many zones of dense rock.
Davis: Can you tell me about the age and type of the majority of the electrical cables in your system?
The majority of the cable in our system is # 2 XLP (cross linked polyethylene) unjacketed cable that was originally installed in 1960s through the late 1980s and started to regularly fail in the 1990s.
Davis: Were you having reliability issues you were having with your older cable? If so, what was happening and where?
Yes we were. In fact, there had been some pretty significant failures in several different periods. I personally arrived at this job in 1991 and was welcomed with two sub-divisions losing power on Christmas eve of 1992. This occurred in the Woodmoor and in the Gleneagle neighborhoods where power was out for 8 hours. Then we had another big outage in the next year on Super Bowl Sunday, in the same Woodmoor subdivision where members didn’t have power for another 6 hours. And the worst was in the winter of 1993 when it was cold and we had most of the Gleneagle subdivision out of power for 12-14 hours. We started a pro-active cable replacement program at that time with an annual budget of $1M dollars per year. In our rural areas we can replace cable for about $15/ft, but cable replacement is very expensive, especially in the rocky areas where it can go up to $85/ft with all the boring that is required to get through the rock. And because the cable is all in nice, residential neighborhoods, we had a lot of members complaining about us ripping up their beautifully landscaped front and backyards.
Davis: How did you learn about electrical cable rejuvenation?
I was at a technology trade show when I was introduced to the concept about 8 years ago. I was pretty skeptical at first. But I was intrigued, especially by the price tag. I learned that cable rejuvenation with injection is about 40% less than cable replacement. This really interested me knowing that I could make our $1M dollar budget go a lot further with cable rejuvenation. And the fact that the cable injection / rejuvenation came with a 40 year warranty, was almost better than the results of cable replacement.
Davis: What made you want to pursue electrical cable rejuvenation? Was cable replacement also considered?
When we determined the need to replace our aging cable in the early 1990s, we had over 600 miles of cable that would need to be replaced as soon as possible. Cable replacement had three negative consequences: (1) it’s expensive, (2) it’s time consuming and (3) it involves a lot of member contact, i.e. physically digging up people’s yards which does not make for happy members, no matter how much explaining you do. The idea of doing far less or no digging was extremely attractive to us. We only have to dig where there is a splice and only a small pit in fact. This is especially important to our residential members where physical appearances are very important.
Since I was still skeptical, I asked for a list of other utilities like ours that were already customers of Novinium, the company that had introduced me to this concept at the tech show. They gave me a list of other cooperatives, just like ours, so I called them all to find out what they thought of the process. I don’t think I would have even considered this technology without all the positive testimonials from other electrical utility managers who actually understand the predicament so many of us face with aging electrical cables.
Davis: Tell us about the process of injecting. What did it involve in your case?
Because I was skeptical of the process of cable injection and rejuvenation, we decided we should first do a pilot project. We went straight to the cable that had experienced the biggest failures. We did this to get a better understanding of the process so we would know what to look for, which cables you should and shouldn’t rejuvenate, how to test etc. That was about 8 years ago now. We are now very skilled at this process. We are using the Novinium’s Sustained Pressure Rejuvenation (SPR) with Cablecure injection fluid and the process significantly increases the reliability of the injected cable and increases safety during injection.
In the last 4 years we have been injecting about 70,000 feet of cable per year which means we are able to treat far more cable with our budget than we could if we were having to replace that same amount of cable. Over the past 4 years we have rejuvenated 289,876 feet of cable and have had zero failures on any of our rejuvenated cable.
Davis: What benefits have you seen from this project?
- Cost effective
- Addressing more cable, more quickly
- Providing reliability faster and more economically
- Allows for pro-active asset management planning for aging electrical infrastructure
- Happier members –i.e not digging up front and back yards, streets, neighborhoods
Davis: What did you learn from this process?
Our operations personnel definitely had to adjust early on. They were used to spending all their time doing line-work, so the process took some time to adjust to. But now that they no longer have to deal with power outages in the middle of the night, they are fully on board with cable rejuvenation.
Replacement hasn’t gone away entirely as we still are replacing our bigger, 3-phase feeder cable so we can upgrade their capacity for the growth in our community. It is our single-phase feeders that are targeted for injection.
Davis: What advice would you give other utilities looking to replace a lot of old cable?
I would advise other utility managers to talk to other utility managers, just as I did. Call me and talk to me and other utilities that are facing similar situations. Utilities interested in pro-actively treating their aging electrical cables should definitely include cable injection / rejuvenation into their asset management plans to quickly address more cable, to quickly prevent failures and outages and do so for 40% less than cable replacement.
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