Mitigation of Transmission Lines against Bird Hazards - the Israeli Experience EDM International Conference on Overhead lines, Fort-Collins, CO, March 29 - April 1, 2010 Dr. Ofer Bahat 1 University of Haifa and the Technion Institute of Technology, Haifa, Israel; BirdsVision Ltd. Summary The extensive use of transmission lines by different bird species in Israel for perching and roosting causes severe damage to the transmission network, mainly to 110 and 161 KV lines but also rarely to a 400 KV line. Birds are seldom electrocuted when perching on lower arms of transmission poles, while in close proximity to the above wires. However, a much more common phenomenon occurs when birds' streamers produce flashovers that result in outages. These may account for more than 90% of the overall damage to transmission lines in Israel, including several dozens of events of severe outages every year. Most of them are caused by wintering birds in specific locations. Costs of such events vary and may reach several hundred-thousands $ US each or even more. The Israel Electric Corporation uses several mitigation devices to prevent outages. These include spikes, wires, additional perches, "umbrellas" and insulating sleeves. These devices considerably improved the situation in some areas, but on the long-run proved to be insufficient and the damage remains severe. The current paper describes the causes of the outages, and the various measures that were implemented to reduce the damage. A major conclusion of the paper is the need for a new approach to reduce the number of outages: This should involve careful planning of transmission line development in the vicinity of important bird areas, implementation of new systems that will efficiently prevent bird activity on transmission lines and long-term maintenance of these systems. Key words: Birds, transmission lines, roosting, perching, outages, bird streamers, flashovers, mitigation measures. 1 bahat@shani.net 1
Introduction Since the mid 1990 s, systematic bird damage to transmission lines has been observed in certain areas of Israel. This damage involved perching and roosting birds of several species, including mainly migrating White Storks (Ciconia ciconia) and wintering Black Storks (Ciconia nigra). In addition, wintering raptors, including Long-legged Buzzards (Buteo rufinus), Common Buzzards (Buteo buteo), Imperial Eagles (Aquila heliaca), Black Kites (Milvus migrans), Saker Falcons (Falco cherugg) and European Kestrels (Falco tinnunculus) are observed regularly perching on transmission lines while foraging during daytime. Most of the raptors tend to perch on the upper arms as single individuals. However, Black Kites which are highly gregarious, usually perch in groups on a single pole (O. Bahat pers. obs.) (see Fig. 1). Fig. 1: Black Kites (Milvus migrans) perch on the different arms of a 161 KV pole, equipped with different deterrent and insulated devices (photo: Ofer Bahat ). 2
Small birds such as Turtle Doves (Streptopelia turtur) and also passerines such as European Starlings (Sturnus vulgaris) regularly use the transmission line poles and wires for perching during winter or for some resident species also in other seasons. Fig. 2: Hundreds of European Starlings (Sturnus vulgaris) may perch on a single 161 KV pole during their daytime wintering activity in Israel (photo: Ofer Bahat ). Data that have been collected since the late 1990s clearly show that the roosting activity of certain species, mainly wintering Black Storks (Ciconia nigra) on steel poles of transmission lines (110 and 161 KV), is a major cause of outages on these lines (1). In addition, other data showed that some migratory species such as the White Stork (Ciconia ciconia) regularly use transmission lines for roosting in certain areas during their migration over Israel. As more and more electrocuted birds were found since the mid 1990s (1) and the number of outages related to bird activity increased, it became obvious that this phenomenon is of much concern and solutions are needed to reduce the damage. Smaller species such as doves or passerines cause no obvious damage to the transmission lines due to the random use of the poles for perching by these species, their much smaller size and thus smaller amounts of produced 3
streamers and the fact that they often perch on wires and thus cause no outages. However, systematic use of transmission lines' poles for perching or roosting by larger species such as raptors and storks in Israel, is a reason of much concern, as the magnitude of power outages which is in probable relation to roosting large avian species augmented up to over 90% of the overall annual outages on transmission lines in Israel (Bahat pers. comm. based on IEC unpublished material). Inspection of the outages in the transmission lines showed that birds are electrocuted on a limited scale (probably up to few dozen of individual birds every year difficult to assess due to predator activity and high removal rate), while roosting on the middle or lower arms of the 110 or 161 KV steel poles (O. Bahat pers. obs.). However, it has been clearly shown that birds such as raptors or storks usually perch or roost on the upper arms, and therefore most of the outages are the result of the bird s streamers of semi-conductive effluent that bridge the gap between the pole arms and wires, pollute the insulators below and eventually cause flashovers (1). Since the late 1990s, the Israel Electric Corporation (IEC) started to implement different devices and modifications to 110 and 161 KV transmission line poles, in an attempt to prevent bird perching and roosting on the poles' arms and prevent the damage of flashovers caused by the birds' streamers. These devices included: 1. Spikes These are metal made devices that were produced by the IEC and were fixed on the upper side of the upper arms of transmission line poles, on the edge of the arms above the insulators (see fig. 3). Their designated role was to avoid perching of birds in this sensitive position. 2. Wires - These are also metal made devices that were produced by the IEC and were fixed on the upper side of the upper arms of transmission line poles, connecting the edge of the arms above the insulators to the central pole (see fig. 3). Their designated role was to avoid perching of birds along the upper arms. 4
3. Additional perches These were also metal made devices that were produced by the IEC and were fixed on the top of the pole. Their designated role was to attract birds to this upper position and reduce the pressure on the upper arms (see fig. 3). 4. "Umbrellas" - The IEC together with Raychem Ltd., started during late 1996 to develop new mitigation solutions based on insulation of the wires and use of "umbrellas" to avoid flashovers. These were implemented in the field since the late 1990s and on a larger scale during the early 2000s. They are fixed on the upper and lower ends of the insulators chain (see fig. 3 and 4). 5. Insulating sleeves These were developed together with the "umbrellas" by the IEC together with Raychem Ltd., from late 1996 to insulate the wires from birds' streamers. They cover the electricity cable in the area below the insulators chain (see fig. 3 and 4). 6. Replacement of ceramic insulators with synthetic ones The IEC modified several dozens of transmission line poles by conducting this replacement. This was done in hope that the synthetic insulators will be less sensitive to the outages caused by birds' streamers (see fig. 3). 5
Additional perches Spikes Wires "Umbrellas" Synthetic insulator Insulating sleeve Fig. 3: Different devices and modifications that were installed on a 161 KV transmission line pole, in an attempt to prevent bird perching and roosting on the poles' arms and prevent the damage of flashovers caused by the birds' streamers (photo: Ofer Bahat ). "Umbrellas" Insulating sleeve Fig. 4: Closer look at the "umbrellas" and insulating sleeve installed on a 161 KV pole, in an attempt to prevent flashovers caused by the birds' streamers (photo: Ofer Bahat ). 6
Although the use of these devices in some cases substantially decreased the number of outages, the problem is still severe and the damage to the transmission lines is still significant (O. Bahat - pers. comm. based on IEC unpublished material). Accordingly, the present study was aimed to investigate the following issues: 1. Conduct observations during day and night on transmission lines where birds' activity takes place, in order to observe bird activity on poles that were fitted with mitigation devices, compared to unfitted poles. 2. Identify the bird species that perch or roost on the poles, and analyze if their activity and behaviour is affected by the mitigation devices. 3. Evaluate the efficiency of the mitigation devices that were implemented by the IEC and the possible use of other potential mitigation measures. Materials and methods Observations were contacted all year round since early January 2009 until the end of February 2010, documenting birds' activity on transmission lines (161 and 400 KV) in three areas: Carmel coast area, south of the city of Haifa (161 KV line), Akko Valley, north of the city of Haifa, (161 KV line) and an area north-east of the town of Hadera (400 KV line), all in the north-west of Israel. Night observations were usually made from a 4x4 car, in order to prevent disturbance to the birds, at specific locations not closer than 150 meters from the transmission poles, to prevent disturbances to the birds' activity. Daytime observations were also conducted from a car for the same reason. Night observations started 2 hours before sunset (at approximately 15:00) and ended in the morning after the last bird left the poles (at approximately 07:00). These were conducted twice every week during the 2009 and 2010 winters, when birds' activity was at its peak, and once a week in other seasons in the three study areas. Daytime activity observations covered the perching and foraging behaviour of birds around and on transmission line poles. They were conducted after the roosting birds left the transmission line (at approximately 06:00) until first arrivals of roosting birds (at approximately 15:00). 7
The observation equipment included 8x42 Leica binoculars and 15-60x70 Kowa telescope, in addition to 22x Canon 750i DV camera. Night observations were made with the use of a Cyclop 1081 Star Light Scope (SLS), and FLIR Systems P640 thermal imaging radiometer. Results Most bird activity in the three study areas was performed by a very limited number of species: Nocturnal activity was solely conducted by the Black Stork (Ciconia nigra), the only species in the study area that regularly uses transmission lines for roosting. This species usually starts to appear at the study areas during September on its early migration from its nesting habitats in northern Europe to its wintering grounds in Israel and further south into Africa (8). However, significant roosting on transmission lines in the study area started only on late October. The wintering of the Black Storks in the study area, including the use of transmission line poles for roosting, continued until mid March, when the birds migrated north. A peak of use of the poles for roosting took place on the autumn migration from late October until late November with regular roosting on the poles in all the study area. Maximum number of birds on a single pole was 21 for a 161 KV pole and 25 for a larger 400 KV pole. However, the number of birds on a single pole usually did not exceed 15 and 20 for the 161 and 400 KV poles respectively. Later during the winter months, the roosting on the pole became more random, probably also because of much more severe weather conditions with strong winds and rains that prevented the regular use of the poles for roosting. Birds' activity on the lines gradually decreased from late February. The Black Storks roosted regularly in high numbers on the protected poles, ignoring the spikes that were placed at the arms ends and roosted nearby (see fig. 5). Even when birds came to roost at near or complete dark, they did not seem to be bothered by the spikes and there were no observations on any casualties caused by missed landings. The birds behaved perfectly well under nocturnal conditions and found a safe landing place on the arm. In addition, the Black Storks often used the added wires for perching as well, although these 8
wires tend to move, therefore the birds are not stable for a while after landing, but eventually stabilize themselves and remain on the wires, but much less in numbers compared to the arm itself (see fig. 6). Fig. 5: Black Storks (Ciconia nigra) roost on the upper arms of a 161 KV pole. Note the spikes at the arms tips, the "umbrellas" above and below the chain of insulators and the insulated sleeves underneath the insulators (photo: Ofer Bahat ). Fig. 6: Black Storks (Ciconia nigra) arrange their roosting positions on the upper arm of a 161 KV pole. Note the two birds that use the added wire as an additional roosting position (photo: Ofer Bahat ). 9
The additional perches that were constructed on the upper part of the central pole were regularly used by Black Storks for roosting. However, this did not result in a reduction in the use of the upper arms by the birds and simply increased the overall number of storks on these poles (see fig. 7). Fig. 7: Black Storks (Ciconia nigra) use the additional perches on the top and the sides of a 161 KV pole for roosting (photo: Ofer Bahat ). The installation of "umbrellas" on the top and bottom of the insulators chain, of course has no effect on the birds use of the pole's arms, however observations show that very often, in areas where birds use the poles regularly for roosting, the "umbrellas" are extensively covered by bird streamers. The same is also true regarding the insulated sleeve which covers the energized wire underneath the insulators. Regarding the replacement of ceramic insulators by synthetic ones, it turned out that the ceramic insulators were more resistant to the outages compared to the synthetic insulators and therefore these replacements were stopped (O. Bahat - pers. comm. based on IEC unpublished material). Birds' diurnal activity in the study area varied according to the area: European Kestrels (Falco tinnunculus) commonly used the transmission lines (both 161 and 400 KV) in low numbers, as hunting observation posts all year round. In the Akko 10
valley, wintering raptors including Buzzards (Buteo buteo) and Long-legged Buzzards (Buteo rufinus) occasionally used the poles for perching during daytime. A rare use of the poles was also documented by wintering Imperial Eagles (Aquila heliaca). However, wintering Black Kites (Milvus migrans) regularly perched on transmission line poles at the Akko Valley area. Black Kites are highly gregarious, and they were usually seen perching in groups of about 10 birds on upper and lower arms alike, and up to 33 kites were observed on a single pole (O. Bahat pers. obs., see fig. 1). Among the smaller avian species, wintering European Starlings (Sturnus vulgaris) occasionally perched in high numbers on the transmission line poles at the Akko Valley. In some cases, the highly social Starlings aggregated in their hundreds on a single pole (O. Bahat pers. Observation, see fig. 2). As a conclusion, the study data show that the use of the different deterrent devices which have been installed by the IEC on transmission line poles in order to prevent bird perching and roosting on these poles, has very limited effect, if any. It seems that the efficiency of these devices to prevent bird activity on the poles in very slim, and that the birds find different ways to use the poles for perching and roosting despite the installation of these devices. However, it seems that the installation of the insulated sleeves and umbrellas reduced the damage of flashovers in some areas, but the overall picture shows that their effect is limited due to their limited ability to insulate these extremely high voltage, and therefore on the long run the insulated sleeves and "umbrellas" do not give a sufficient solution to the problem stopped (O. Bahat - pers. comm. based on IEC unpublished material). Comparing previous data on the number of outages and their consequent damage (1) to the period of the present study, it seems that although the number of events and their severity differs considerably in between years and specific cases, the general estimation of the damage's magnitude during the study period, remains the same as during the previous one (1): the direct repair damages costs for the utility are approximately 70K $ US for one event. Total damages estimated for a single event may reach 400K $ US (including costs of unsupplied 11
electricity, excluding possible compensations to factories and other possible indirect costs) (Bahat - pers. comm. based on IEC unpublished material). Accordingly, as during each winter a minimum number of 20 outage events takes place in the study area, the damage to the utility, (excluding potential indirect costs) is in the magnitude of 8 million $ US in this area alone. Discussion The present study investigated the impact of various mitigation methods of transmission lines against bird hazards in three different areas in northern Israel. The results of the study clearly demonstrate that the efficiency of the mitigation methods that have been used in the study area is very limited, and that the presence of transmission line poles in areas where resident, wintering or migrating avian species occur in high numbers, is very hazardous in terms of damage to the utility. Once these poles are attractive to the birds for perching and roosting, and once the surrounding area has high carrying capacity due to much available food at fishponds and in the fields, the resulting damage is very high. As has been shown in other studies, bird streamers are a significant cause for flashovers and consequent outages in many countries, and by many bird species (2, 4, 9, 10, 11). The present study observations suggests that aggregation of many birds on one pole when roosting or perching, has a much higher damage potential due to the much higher quantities of streamers secretion which may cause higher rates of flashovers and outages. This is further increased by roosting birds that spent many hours (typically 15 hours during the winter) on the poles constantly, thus dramatically increase the numbers of streamers secretion. As has been shown earlier, The avian streamers secretion is predominantly determined by the internal digestion of food by the birds, and not by external factors (1). Although very important work has been done in different countries and in the study area to implement mitigation measures to the problem of birds streamers in transmission lines (3, 4, 5, 6, 7, 10), it seems that these measures give only 12
partial solution to the problem. Due to the very high voltage and the still limited options to insulate the wires, there is maybe a need for a different approach that will combine more active detection and deterrence methods that will overcome the severe problem of habituation by birds, and will enable to keep the poles "sterile" without any bird activity. In addition, management actions, which will reduce the availability of resources to birds in the vicinity of the transmission lines, have also an important potential to substantially reduce birds' activity in such areas and hence further reduce the damage to the electricity network. Acknowledgements I am grateful to Hezi Samoha, Head of Transmission Lines Department, Israel Electric Corporation, for his important support and the development of mitigation solutions. I also thank Amir Balzam, head of the north district transmission lines maintenance department of the Israel Electric Corporation, for his support in the field and for providing highly valuable information. Bibliography 1. Bahat, O. 2008. Wintering Black Storks (Ciconia nigra) cause severe damage to transmission lines in Israel A study on the risk and mitigation possibilities. Pp. 177-198 in: Proceedings of the 10th International Conference on Overhead Lines: Design, Construction, Inspection and Maintenance. March 31 through April 3, 2008, Fort Collins, Colorado. 2. Bekker, H.J.J. and Hoch, D.A. 2002. Analysis of factors contributing to unexplained transmission line faults on a high voltage transmission network. Pp. 655-660 in: Proceedings of the 6 th Africon Conference in Africa, University of Natal, S.A. 3. Burnham, J.T. 1995. Bird streamer flashovers on FPL transmission lines. Power Delivery 10(2): 970-977. 4. Burnham, J., Carlton, R., Cherney, E.A., Couret, G., Eldridge, K.T., Farzaneh, M., Frazier, S.D., Gorur, R.S., Harness, R., Shaffner, D., Siegel, S., and 13
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