The Evolution and Application of Outage Mitigation Methods

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So how do you best protect against animal-based threats, and is it even possible to achieve zero animal-caused outages once applied?

IEEE-1264TM, “IEEE Guide for Animal Deterrents for Electric Power Supply Substations,” discusses many strategies to combat the issue, and this standard examines various strategies deployed, including simulated natural predators, noisemakers, cover-up materials, animal fences and barriers, nest relocation, increased insulator size and spacing, and construction of indoor substations, to name a few. Largely, 10-20 years ago, these methods were experimental in nature when introduced; yet time and experience have exposed both successful and unsuccessful methods.

Data and experience have suggested that the least effective methods include deterrents (see Figure 4) such as simulated predators, noisemakers and smells, as they have shown to exhibit a limited life span before animal adaptation.12 Animal behavior experts explain that this is primarily because animal instinctual behavior leads animals to initially be frightened by these devices, while increased exposure allows them to test and naturally realize that these harmless devices will not hurt them. Scents of predators have been used to simulate a similar threat, which also worked initially, only to have the scent wear off or wash away or the animals became used to the smell and, consequently, aware of the lack of threat.

Various Types of Animal Protection and Their Best Applications – Figure 4


Animal Fences

Some other outage mitigation solutions include limiting animals’ ability to gain access to equipment beyond the protection afforded by standard fencing. One example is the installation of electrified fencing surrounding equipment that is more prone to land-based animal intrusion. When applied to areas that tend to be more problematic, the fence can be more or less expansive as needed. A limitation associated with these systems is that while they are effective for ground-based animals, they do not keep avian animals out of the area (with open sky access). Burrowing animals still could intrude; however, this risk is limited because the animals do feel the electric field created by the fence and tend to avoid the area.


Animal Guards
Installing animal guards is another approach. Animal guards are mounted on equipment to block animals from getting into electrified conductors and can provide protection from a limited type of animal contact, but certain animals that are more resourceful (e.g., squirrels) have shown their ability to bypass these animal guard protections. These are considered somewhat effective, low-cost solutions for protection of distribution transformers or any other lower cost, short-lead-time equipment. In fact, most utilities report that they proactively install this type of equipment on a transformer when a new installation or replacement is commissioned.


Animal Cover-up
The most complete and proven method involves the cover-up design approach, where insulation covers are added to electrified equipment and/or grounded structures in the vicinity of energized risk points, thus providing improved insulation and protection in a specific and targeted way. This method dramatically increases the span that’s necessary for an animal to bridge the contact points and minimizes risks relating to gaps being accessible to crawling animals or inquisitive birds. Cover-up typically is applied to equipment in an area that needs additional span distances, including transformer bushings, circuit breaker bushings and others that are most vulnerable to animal contact.

This design eliminates high-risk bridging and does not allow animals to bypass the protection by climbing around or finding another access point for intrusion, which can be a limitation of other protection methods. Additionally, the risk of bird intrusion is eliminated since the cover-up guard protects the equipment in all directions, not just for land-based intrusion. In practice, cover-up protection eliminates the root cause of animal intrusion by increasing the span distance rather than managing the symptom of animal contact.

Two main types of cover-up solutions are available, including a one-size-fits-all or a customized cover-up design, which is built to precisely fit specific equipment types. For a cover-up to work most effectively, it should completely cover the equipment it surrounds because ill-fitting covers can be bypassed by animals or can leave gaps and spaces where a contact or nesting can be made. While the best covers will maintain a tight fit to preclude intrusion, it also is critical that they are durable. IEEE-1656TM is an engineering specification that establishes guidelines for animal protection products, such as ultraviolet exposure protection, impact resistance, salt exposure and flame resistance, ensuring that maintenance is virtually nonexistent. This is important not only because it ensures that a long-lasting solution is deployed, but it also has cost recovery implications.


Protection Selection Considerations
When selecting cover-up protection, it is essential to consider long-term concerns that will allow for the cost-effective operation and inspection of the equipment the cover-up protects. Should the equipment require access in a way that necessitates the cover-up’s frequent removal, ease of doing so is a key factor. An additional consideration should include the ability to perform infrared inspections with minimal or no extra work required. Any additional work that is required to remove and then reapply a cover-up during maintenance could be considered extra operating Operations and Maintenance (“O&M”) expense, reflecting another cost driver and proving the value of finding the right cover-up product.



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[12]      Mitigation of Animal-Caused Outages for Distribution Lines and Substations, (1999) EPRI, Palo Alto, Calif. 1999. Report TE-114915.

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This post is the third in a series of seven excerpts from an electric utility industry white paper prepared by FTI Consulting, entitled, THE CASE FOR ELIMINATING ANIMAL-CAUSED OUTAGES IN ELECTRIC SUBSTATIONS AND ON POWERLINES. The full white paper may be downloaded by clicking here.

Darren Barnett

Darren Barnett

Senior Product Manager Wildlife Mitigation Business Unit
Darren holds a degree in Electrical Engineering Technology from Louisiana Tech University and has over 28 years of experience in the electric power distribution industry. Darren’s career started as a Design Engineer for a major transformer and components manufacturer. From there he advanced to positions of increasing responsibility, including Quality Assurance Manager, Engineering Manager and Vice President of Components Operations. Darren is an active member of IEEE and was on the committee that developed the 1656 -2010 testing guide for wildlife mitigation products.