A100-Interaction of Animals and Birds with Transformers

1.0 Transformer tanks and accessories can get damaged during storage or operation by interacting with animals and birds. The types of nuisances and damages are so variable that power engineers sometimes get baffled by these problems. Let me share some experiences on this matter.

2.0 In the 1980s, two banks of 450 MVA 400/220/33 kV transformers operated in a 400 kV substation. The 33 kV tertiary was formed by an open bus connection supported on post insulators. One early morning, a peacock entered the station and spread his tail quill feathers (train) under the tertiary bus, causing a line fault on the tertiary. Due to some mistake in the wiring of protection CT secondaries, the transformer was not isolated by its 220 kV circuit breakers but by a remote backup breaker after considerable delay. The time delay in clearing the fault caused the failure of the bank's transformers. We got a quarter kg copper globule from one of the transformers from the melting of tertiary winding. Transformers had to be taken to the factory for repair. Power engineers sometimes face problems keeping rodents, monkeys, and peacocks from live transformers. In the above station, after this failure, the tertiary bus was insulated with heat-shrunk epoxy tape to avoid inadvertent shorting by birds and rodents.

3.0 In an underground hydropower station, the Buchholz relay in one of the generator transformers was tripping out during peak load. This caused cascade tripping of other transformers. Low voltage testing and DGA showed that the transformer was healthy. After several rounds of this fiasco, it was found that insects were nesting with mud over the oil seals of the breathing port of the silica gel breather. When the port was completely sealed with mud, the oil level rose, and pressure rose above the conservator during peak load. This pressure rise resulted in the exploding of the mud seal. The consequent mechanical vibrations caused the malfunction of the Buchholz relay. Once the oil cup was shielded with a wire net, the problem disappeared.

4.0 In a large autotransformer, the RIP bushing sheds (composite insulator) were damaged by chewing by monkeys frequenting the station. Rats and similar rodents may gnaw the composite insulator sheds while storing RIP bushings.

5.0 Bird droppings can spoil the painting, a common problem at many sites.

6.0 Some of the solutions tried successfully at various sites are listed below:

1) Use of shields to prevent bird droppings

2) Landscaping the station to prevent access to fruits, seeds or nuts

3) Use of bird and animal traps

4) Plastic mimics (owls/ snakes)

5) Screening the nesting locations near to the station

6) Chemical repellents

7) Sticky glues

8) Disturbing noises like ultrasonic sounds

9) Insulating tapes/ heat shrunk insulation/insulation coating/increased electrical clearances

10) Fence barriers/ ultra-smooth climbing guards/ smaller mesh fence/electric fences

Wildlife Protection Cover/Substation Bushing Connection Insulating Covers/Bushing Connection Animal Covers/Bushing Connection Insulating Covers ( United Electric Company, China)

Some new techniques being tried as animal deterrents:

? Structure guards for ground animals;

? Electrical shocks (electrical wires put on attractive places for animals);

? Optical bird barriers (deters birds from unwanted areas by making use of light beams reflected from direct sunlight);

? Lasers

? Birth control (extruded kibbles used to limit pigeon's reproduction).

? Optical gel (a sticky, unpleasant-smelling gel that looks like fire for birds).

7.0 The following reference materials will help power engineers address adverse reactions to transformers from interactions with animals and birds.

7.1 IEEE Standard 1264-2015 Guide for Animal Deterrents for Electric Power Supply Substations, Pages 20.

7.2 IEEE Standard 1651-2010 Guide for Bird-related Outages

7.3 IEEE Standard 1656-2010 - Guide for Testing the Electrical, Mechanical, and Durability Performance of Wildlife Protective Devices on Overhead Power Distribution Systems Rated up to 38 kV

7.3 CIGRE Technical Brochure No.876-2022, WG C3.16, Interactions between Electrical Infrastructure and Wildlife, Pages 152-169 out of 360 pages.

Readers of the Technical Brochure will gain a comprehensive understanding of:

? Factors of collision and electrocution risks

? Wildlife-related incidents on OHL and in substations

? Mitigation solutions to prevent collision, electrocution and wildlife-related incidents for new and existing infrastructure

? Recommendations on how to communicate wildlife interactions with electrical infrastructure

? Suggestions to develop partnerships

? Recommendations on further research to get better knowledge of the topic