Wildlife-Related Outage Management Whitepaper
While vegetation-caused outages tend to occur most often during inclement weather, such as strong storms, excessively windy conditions, ice storms, blizzards, etc., wildlife-related outages can occur any time of day or night, any time of the year, and under any weather conditions.
The first step in preventing wildlife-related outages is to learn what kinds of wildlife are getting on your system, when they are getting on, where they are getting on, why they are getting on, and how they are getting on. Until you know the answers to these questions, you won’t be able to begin to take steps to solve the problems.
In general, outages that occur in substations get more attention than those that occur on distribution lines, because a substation outage will affect a far greater number of people and is usually more costly to repair. For example, if a squirrel gets into a substation and takes out a breaker, it will trip off a whole circuit. However, with overhead distribution, most utilities have programs to isolate faults on the system. As a result, a squirrel can get into a transformer on a distribution line, and it may take out the transformer. While the fault may propagate up-line a few spans and take some customers out, a fuse will eventually take that out at one of the laterals.
The first step in dealing with substation outages is to look at the annual performance of each substation as it relates to wildlife-caused outages. Then, identify the substations with the most such outages, and create a plan to address these.
The goal is to make sure the substation is not attractive to wildlife in the first place. As such, for example, you should have a program in place to inspect the substations on a regular basis to make sure you don’t have small birds nesting in the springtime. While these birds are not physically large enough to create phase-to-phase or phase-to-ground contact, the eggs and the young birds in the nest can be very attractive to raccoons, snakes, and other predators, which can be large enough to create these contacts.
Second, don’t store unnecessary materials or equipment in substations. These items can be very attractive to animals that are seeking refuge. For example, piles of old equipment, boards, discarded PVC pipe, etc., can become homes for mice or rats. And, as with small birds making nests, the mice and rats will likely begin to attract predatory animals, such as snakes, foxes, and owls.
Third, check the perimeter fencing around substations. In most cases, animals that do get into substations do so either by climbing over the fence (such as squirrels, raccoons, and snakes), or gaining access through gaps under the fence (such as squirrels, raccoons, snakes, and foxes). Access through or under fences usually occurs as the result of either broken or damaged sections of fence, or shallow openings under the fence between the ground and the bottom of the fence. It does not take much for an animal to dig out a little bit more under a fence in order to gain access. Make sure there are no gaps or breaks in the fence. In addition, consider extending the fence a bit deeper into the ground, making it more difficult for animals to burrow under.
After adopting these three strategies, if you are still experiencing wildlife-related substation outages, you will need to determine specifically what kinds of wildlife are causing the outages.
For example, if you determine that they are caused by wildlife other than birds, you might find that it makes sense to install special fence systems around the substations. Some of these are fences within fences, such as modular fences that go around equipment within a substation. These can be effective in preventing climbing animals from gaining access to that specific equipment.
If you determine that the outages are being caused by birds, you might want to look at the various cover-up products that are available, such as bushing covers for transformers, insulation for wires, switch barriers on regulators, etc. One consideration in deciding what kind of products to purchase is to ask yourself, “If birds were in here, what could they possibly contact?” Then, find a way to remove or cover that phase-to-phase or phase-to-ground contact.
While substations should be the focus of most wildlife-related outage prevention strategies, there is still a need to devote some resources to the distribution system. This is especially true for lines that are serving critical loads, such as hospitals. The best thing you can do to reduce overhead distribution wildlife-caused outages is to make sure that every distribution transformer that leaves the service yard already has a bushing cover with it. In addition, every surge arrester that goes out to the system should go out with a protective cap on it. All of the jumper wires and connections to these should be insulated. Doing these few things can make a big difference.
Another reason to pay attention to distribution lines is that some outages along these lines can be caused by raptors and other protected species of birds, which are covered under three different acts – the Migratory Bird Treaty Act, the Endangered Species Act, and the Bald and Golden Eagle Act.
Besides the nuisance and cost factors associated with restoring power, these incidents can lead to financial penalties to utilities that, it is deemed, don’t take appropriate measures to prevent such deaths. In 2009, for example, PacifiCorp pleaded guilty to 34 counts of killing golden eagles, hawks and ravens in Wyoming. It was sentenced to pay over $1.4 million in damages (a $510,000 criminal fine and $900,000 in restitution). It was also ordered to spend $9.1 million to repair or replace equipment designed to protect migratory birds from electrocution.
One solution to protecting large birds is to install large colorful balls, spirals or flappers on the highest lines. When birds see these devices, they know something is in their way and tend to fly above them. According to the U.S. Fish and Wildlife Service, such devices can reduce strikes by as much as 75 percent.