Birds Don't Like Wires Over 21 kV
Birds Don't Like Wires Over 21 kV
(OP)
Here is a question that has bugged me for a long time but I never bothered to ask:
Does anyone know why birds do not perch on wires > 21 kV?
There are no 35 kV in this area so I don't know what they think of those.
I know I have never seen them perched on 60 kV or greater unless they are deenergized.
It must not kill them or else you would see dead birds for miles.
Do they not like electric field close to the wires?
Has this ever been studied?
Does anyone know why birds do not perch on wires > 21 kV?
There are no 35 kV in this area so I don't know what they think of those.
I know I have never seen them perched on 60 kV or greater unless they are deenergized.
It must not kill them or else you would see dead birds for miles.
Do they not like electric field close to the wires?
Has this ever been studied?






RE: Birds Don't Like Wires Over 21 kV
Keith Cress
kcress - http://www.flaminsystems.com
RE: Birds Don't Like Wires Over 21 kV
1. Heat (higher loading on these circuits)
2. Higher electric field
3. Larger conductor size
Of course I could be very wrong since I know nothing about birds.
RE: Birds Don't Like Wires Over 21 kV
Once on the wire, you do not feel anything. It's the spark that the birds don't like. I guess that they can sit on an de-energized wire and that they will continue sitting there when the wire gets energized again.
But they will not love the tickling when they leave the wire.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Birds Don't Like Wires Over 21 kV
http://www.bing.com/videos/search?q=high+voltage+w...
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Birds Don't Like Wires Over 21 kV
Although some wires do operate at uncomfortably high temperatures, many are also operated close to ambient. For many of our transmission lines, the lines will be warmer while de-energized on a still sunny day, than carrying typical power flows on a windy (> 2 m/s windspeed) cloudy day.
RE: Birds Don't Like Wires Over 21 kV
Do you get a spark because the bird is one plate of a capacitor and the wire is another plate and when the two get close they discharge?
RE: Birds Don't Like Wires Over 21 kV
The arrangement is actually a capacitive voltage divider, like a capacitive PT, and current depends on equivalent capacitance, voltages involved and the Paschen's and other guy's laws. For a bird, it cannot be a lot of current. But nasty enough.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Birds Don't Like Wires Over 21 kV
A pair of Turtle Doves has discovered, likely through trial and error, that the pine tree over my driveway is close enough to get some heat from the house, but dense enough to protect them from raptors. So they roost in the exact same spot every night and as you might imagine, my car ends up being their toilet. I tried a lot of things to discourage them from that roosting site, shiny balloons, mylar ribbons, a fake owl on the chimney, all with limited or no success. So for the past week I have been going out after dark, rain or shine, with my head lamp and a "wrist rocket" sling shot to fire a group of tiny pebbles into the tree where they are, just enough to disturb them. The first night they came back after an hour, the third night it was 3 or 4 hours, last night they finally did not come back. They learned...
"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington
RE: Birds Don't Like Wires Over 21 kV
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I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
The rain does not boil off of transmission lines.
A line of any length at that temp would have losses greater than the load.
Bill
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"Why not the best?"
Jimmy Carter
RE: Birds Don't Like Wires Over 21 kV
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Birds Don't Like Wires Over 21 kV
Way back, they used to only run the ACSR 75°C normal rating and 90°C emergency. Later they used 90°C normal and 120°C emergency. They started to develop the high temperature wire to push more power down the lines. If the lines are lightly loaded, electrically, they are not too much above ambient and in the very cold weather, they will ice over and start galloping because of the shape of the ice. During the summer when everyone is running the air conditioner, the wire temperature goes up and the wire can sag an extra 20 feet from the unloaded position on an average 800 foot span.
Below is the output from a Sag-Tension program for a 795 MCM ACSR conductor on an 800 foot span in a 120 mph hurricane. When the wire is first strung, the sag is 13.50 feet at 60°F. After it creeps and gets loaded up, the sag goes to 25.36 feet at a max emergency operating temp of 120°C. The wire tension goes up to 12,907 pounds in a 120 mph wind from the initial stringing tension of 6501 pounds. The conductor has 26 aluminum strands over 7 steel core strands and is 1.108 inches diameter.
WC Weather Case Condition Allowable Actual Allowable Actual Allowable Actual % of OK No. Description % of % of Tension Tension Catenary Catenary Allowable or Ultimate Ultimate (lbs) (lbs) (ft) (ft) Capacity NG. ----------------------------------------------------------------------------------------------------------------- 6 60F Initial RS 33.0 20.6 6501.2 5929.1 62.5 OK 6 60F Creep RS 18.0 18.0 5667.1 5164.7 99.9 OK * 11 Hurricane Initial RS 50.0 41.0 12909.3 3664.5 82.0 OK 12 NESC LIGHT Initial RS 50.0 26.3 8272.8 5796.4 52.5 OK Ruling Span Sag Tension Report ---Weather Case--- | --Cable Load-- | -----R.S. Initial Cond.---- | ------R.S. Final Cond.----- | | | | --------After Creep-------- | # Description | Hor. Vert Res. | Max. Hori. Max R.S. | Max. Hori. Max R.S. | | -----Load----- | Tens. Tens. Ten C Sag | Tens. Tens. Ten C Sag | | ---(lbs/ft)--- | (lbs) (lbs) %UL (ft) (ft) | (lbs) (lbs) %UL (ft) (ft) | -------------------------------------------------------------------------------------------------- 1 15F 0.00 1.09 1.09 7690 7678 24 7018 11.40 6828 6814 22 6229 12.85 2 25F 0.00 1.09 1.09 7399 7386 23 6752 11.85 6533 6518 21 5958 13.43 3 30F 0.00 1.09 1.09 7265 7252 23 6629 12.07 6391 6376 20 5828 13.73 4 40F 0.00 1.09 1.09 6996 6982 22 6382 12.54 6131 6115 19 5590 14.32 5 50F 0.00 1.09 1.09 6741 6727 21 6149 13.02 5890 5874 19 5369 14.91 6 60F 0.00 1.09 1.09 6501 6486 21 5929 13.50 5667 5650 18 5165 15.50 7 70F 0.00 1.09 1.09 6277 6262 20 5724 13.98 5464 5446 17 4978 16.08 8 80F 0.00 1.09 1.09 6060 6044 19 5525 14.49 5275 5257 17 4805 16.66 9 90F 0.00 1.09 1.09 5859 5842 19 5340 14.99 5101 5082 16 4646 17.23 10 100F 0.00 1.09 1.09 5671 5654 18 5169 15.49 4938 4919 16 4496 17.80 11 Hurricane 3.33 1.09 3.50 12909 12833 41 3664 21.85 12907 12830 41 3664 21.86 12 NESC LIGHT 0.83 1.09 1.42 8273 8253 26 5796 13.81 7579 7558 24 5308 15.08 15 Rule 250 D 0.40 2.09 2.13 10580 10546 34 4945 16.19 10279 10243 33 4803 16.67 16 75C(167) 0.00 1.09 1.09 4668 4648 15 4248 18.84 4114 4090 13 3739 21.42 17 90C(194) 0.00 1.09 1.09 4368 4346 14 3973 20.15 3871 3846 12 3516 22.78 20 120C(248) 0.00 1.09 1.09 3887 3863 12 3531 22.68 3483 3456 11 3159 25.36 23 200C(392) 0.00 1.09 1.09 3081 3050 10 2788 28.75 3065 3034 10 2773 28.90 24 250C(482) 0.00 1.09 1.09 2880 2846 9 2602 30.81 2868 2834 9 2591 30.94 25 BLOWOUT 60 0.55 1.09 1.23 6938 6921 22 5644 14.18 6152 6132 20 5001 16.01 26 FIRST CRACK CHK 0.55 1.09 1.23 6938 6921 22 5644 14.18 6152 6132 20 5001 16.01 27 Max Temp 0.00 1.09 1.09 2880 2846 9 2602 30.81 2868 2834 9 2591 30.94 28 Min Temp 0.00 1.09 1.09 8143 8131 26 7432 10.77 7323 7309 23 6681 11.98 29 Rule 230B1 0.83 1.09 1.42 8273 8253 26 5796 13.81 7579 7558 24 5308 15.08_____________________________________
I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
RE: Birds Don't Like Wires Over 21 kV
I have never seen it but has anyone else seen rain turning to steam or water vapor on transmission lines??
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Birds Don't Like Wires Over 21 kV
http://www.southwire.com/ProductCatalog/proddetail...
500kV switch opening.
https://www.youtube.com/watch?v=PXiOQCRiSp0
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I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
Uhhh, you might want to reconsider that. Simply no- in fact the opposite. :) :) For a structural guy this rivals what many long standing EEs post here- and they know their stuff. Great info!
As for not seeing steam- its a guess- but its possible that since water has a much higher thermal absorption capacity that it cools the conductor down significantly over 2ft/wind or still air temps.
RE: Birds Don't Like Wires Over 21 kV
Thanks for the kind words. I've picked up a little Electrical knowledge over the past 43 years of designing structures for Substations. The fault current gives me a Short Circuit Force on the buswork that I use to design the structure with other wind loads for extreme conditions. I know enough not to raise my hand too far inside a substation and to shuffle my feet if I hear any arcing (too much step potential between one foot and the other if you run).
AFA, the rain on hot conductor, I'm only guessing that it flashes to steam as the drops hit if it is indeed at or near max operating load. On foggy days you can hear the crackle around the wires which I assume are the tiny water drops flashing to steam. I'll have to ask the EE over the cubicle wall.
_____________________________________
I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
If you are actually "running", only one foot will be in contact with the ground at any time. However, a good thing to keep in mind.
RE: Birds Don't Like Wires Over 21 kV
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Birds Don't Like Wires Over 21 kV
How many pounds of force does 80ka crank out? Around here we don't have to worry about that- yet lol.
RE: Birds Don't Like Wires Over 21 kV
If you saw my bulk, you would realize it has been many years since I have "run" with only one foot on the ground at a time. :)
As far as the 80 kA, I'll have to dig out my spreadsheet and see what the figure is. You EE's know that it depends on the spacing of the bus. The equations in IEEE 605 are pretty conservative from what I have learned. I am the chair of the committee that is revising ASCE 113 and we are going over the first edition (I was Vice-Chair on that one) and adding some stuff.
AFA the crackling, I will defer to your expertise but it seems to happen in fog or very high humidity.
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I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
That's when the dirt and salts coating everything become more conductive and leakage currents begin worming their way thru it all. We get that here in our coastal town in-spades. While walking the dog, my wife and I have fun trying to see the actual arc-light given off by this process. We manage to see it whenever there isn't bright street lighting. Try it next time you hear it in the dark. It's across the insulators usually.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Birds Don't Like Wires Over 21 kV
_____________________________________
I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
Actual line temperature is often lower than rated line temperature since the ratings are for a near worst case weather day. If the wind is 4 ft/s instead of the typical assumption of 2 ft/s, the conductor temperature would be reduced from 200C down to around 150C.
If I have done the thermodynamics correctly, evaporative cooling from rain at 0.2 cm/hour falling on a 795 conductor would reduce the operating temperature by around 15C.
RE: Birds Don't Like Wires Over 21 kV
As to the OP, I have seen birds sitting on the 28 kV lines in our province [Ontario, Canada] more often than I can recall, but they generally eschew anything 44 kV and above; the only exception is that ospreys seem to have no issues working around energized 44 kV equipment, often building nests one stick at a time into great sprawling affairs that render ganged manually switched devices completely inoperable [they must have an osprey nest-building construction code by which they choose only dry, high dielectric strength wood as a building material, as I have never heard of a feeder tripping off due this activity].
Since ospreys are a protected species, my utility's response has typically been to build a new non-electrical structure of slightly greater height in near geographic proximity and re-locate the entire nest onto the new structure in the off-breeding season while the birds are down south. Only very rarely have the returning ospreys scorned the new location and re-built their nest onto the same device.
I once recall seeing a very determined pigeon trying to alight on one phase of a 230 kV open-air bus; alas, every time it landed, it again flew back off, but stubbornly repeated the attempt a few feet further along the buswork . . . after fifteen minutes it finally gave up.
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Birds Don't Like Wires Over 21 kV
http://www.eng-tips.com/threadminder.cfm?pid=608
I try to answer technical questions about T-Lines and substations there, so if you need answers to structure questions, post over there.
As far as hi temp conductors, we have looked at 3M (don't remember the name) which IIRC, you basically rent from them, at least it was that way when they were trying to get to market for low sag conductor. And your Ospreys made their way south to my area of Texas so we built a structure near the nest and transferred it over.
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I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
I dug out my spreadsheet and ran a 50 GVa fault for a 345kV substation with 18'-0 phase spacing which I calculate will have a fault current of 83,600 amps. The load per foot of a 6" bus will be 42.4 pounds per foot for the SCF. In a 140 mph wind, the wind on the bus will be another 26.3 pounds per foot. When we combine SCF and 140 mph hurricane wind we take 80% of the short circuit current, so the combined wind and SCF force is 53.4 pounds per foot and a typical 30'-0 span would have 1.6 kips at the insulator on a bus support column.
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I have been called "A storehouse of worthless information" many times.
RE: Birds Don't Like Wires Over 21 kV
Congratulations to the designer who, in addition to other parameters, and so many of these birds are predicted as a possible problem and the extra weight.
RE: Birds Don't Like Wires Over 21 kV