Birds Don't Like Wires Over 21 kV 3

[JohnMcNutt]

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?

 

[Mbrooke]

Welcome and much earned

How many pounds of force does 80ka crank out? Around here we don't have to worry about that- yet lol.

 

[transmissiontowers]

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.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[itsmoked]

AFA the crackling, I will defer to your expertise but it seems to happen in fog or very high humidity.

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

 

[transmissiontowers]

I should have remembered that we had a long dry spell with little rain a few years ago in Galveston and we were having to wash insulators with deionized water at a huge expense.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[bacon4life]

Several kinds of wire including AAAC ACCR, GAP and ACSS can operate at 200C or higher.

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.

 

[crshears]

Hey there TxTowers, allow me to add my welcome to everyone else's.

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]

 

[transmissiontowers]

I usually hang out here:

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.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[transmissiontowers]

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.

_____________________________________
I have been called "A storehouse of worthless information" many times.

 

[panter]

At two 110 kV transmission line pillars that extend beyond our workshops during the preparations for the migration of crows in early morning and twilight , there are thousands of them.
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.

 

[HamburgerHelper]

During bird migration season, I once saw hundreds of birds all land on a distribution line. When they got spooked by a passing car or truck, they flew off all in unison and caused the line to bounce up and down like you see with galloping transmission lines. I wouldn't have thought birds could cause that and maybe it doesn't happen often. I tried watching for it again and never could see them get the line bouncing around like I did the first time I saw it.