The term wildlife protective device is relatively new to the power industry and refers to any device used on the network to reduce outages due to the impact of wildlife. Other terms sometimes used to describe these devices include animal guards, bird guards, bird deterrents, to name a few.
This article, contributed by INMR Columnist Jonathan Woodworth, provides an overview of such devices used to reduce power system outages caused by wildlife. Design considerations, testing methods and installation issues are all covered.
Devices used to mitigate the effect of wildlife on power systems have been in existence for many decades now. Figure 1 shows an example of such a wildlife protective device (WPD) used on an arrester.
In fact, WPDs are used not only on arresters, but on all types of equipment where animal contact between earth and the high voltage side of the insulator is possible. Figure 2 shows WPDs on a distribution system recloser bushing as well as on the arresters.
Standards & Guides
IEEE 1656 is a Draft Testing Guide for WPDs, as yet not published but already in the final balloting stages. The Guide defines WPDs as “A device, guard or structure providing electrical isolation from high voltage equipment that is intended to prevent contact by wildlife that would result in a momentary flashover or short circuit of the electrical system. Contact by wildlife should not produce physical harm to either the equipment or wildlife.”
This Guide, which was initiated in an attempt to eliminate ineffective designs, will be the first ever on how to test WPDs in order to verify their quality, effectiveness, capabilities and environmental withstand. When published later this year, it will become the only document that covers this important topic anywhere in the world. The focus is entirely on wildlife guards up to 38 kV, which seems appropriate for this type of device since equipment in this voltage range is short enough that the potential for wildlife contact between the HV end of the insulator or bushing to earth is reasonably high. At voltages above these levels, insulator length and spacing is usually great enough to make such a device much less necessary.