Long span between power poles - Page 1
Forum section: electronics / general

author: Circlotron
author_rank: Super Contributor
timestamp: September 16, 2023, 12:25:14 pm
content: Was looking at some electricity wires today and they seemed to go a long way to the next pole. Pulled it up on Google Earth and the distance was 700 metres! These were ordinary concrete poles too, not huge pylons. Can't imagine how the wires would not touch in the wind. In the Google Earth link can just make out shadow of the two poles from the road on the left to the property on the right.https://earth.google.com/web/@-38.07736772,145.69252541,67.19248015a,1199.65974883d,35y,0h,0t,0r

author: themadhippy
author_rank: Super Contributor
timestamp: September 16, 2023, 01:01:23 pm
content: Quotethe wind hits the lines from the same direction so they both should move in the same direction,

author: Ian.M
author_rank: Super Contributor
timestamp: September 16, 2023, 01:23:18 pm
content: Its quite common to fit mid-span insulated spacers to long spans (e.g. river crossings) in windy areas.

author: The Electrician
author_rank: Frequent Contributor
timestamp: September 16, 2023, 02:14:06 pm
content: I wonder what the longest power line span in the world is?Here's a candidate:https://www.tacomadailyindex.com/blog/tacoma-power-celebrates-tacoma-narrows-crossing-completion/993822/

author: rstofer
author_rank: Super Contributor
timestamp: September 16, 2023, 06:38:11 pm
content: Long lines sag when overloaded during the summer heat waves (California). They touch the ground and we have a devastating wild fire. And really long outages!

author: soldar
author_rank: Super Contributor
timestamp: September 16, 2023, 06:40:01 pm
content: Quote from: Circlotron on September 16, 2023, 12:25:14 pmProbably in Australia they can get away with longer distances because the wires there hang upwards.According tomyGoogle Earth one post is at<coordinates>145.691896,-38.078044</coordinates>and the other at<coordinates>145.696683,-38.078018</coordinates>and the distance between them is 420 metric meters.

author: Circlotron
author_rank: Super Contributor
timestamp: September 16, 2023, 10:33:15 pm
content: Oh yeah, there is another pole that I didn’t notice. So it’s 400m from where I’m standing to that pole then another 300m. Anyway, it looks a long way just looking at it.

author: TimFox
author_rank: Super Contributor
timestamp: September 16, 2023, 10:52:45 pm
content: Last year, a new 230 kV transmission line was installed (replacing a failed one) across the mighty Mississippi River near New Orleans.The towers on each bank are 475 ft = 145 m high, and the river is 3700 ft = 1130 m wide at that crossing.When the previous line failed in Hurricane Ida (one tower collapsed), it had to be dynamited for removal.The Tacoma Narrows line mentioned above is 6240 ft long: the original was installed in 1926, but the towers have been replaced recently.

author: soldar
author_rank: Super Contributor
timestamp: September 17, 2023, 11:06:54 am
content: https://en.wikipedia.org/wiki/Ameralik_SpanThe Ameralik Span is the longest span of an electrical overhead power line in the world. It is situated near Nuuk on Greenland and crosses Ameralik Fjord with aspan width of 5,376 m(17,638 ft) at 64°6′18″N 51°14′16″W. It was built in 1993 by the Norwegian company NTE Entreprise (Nord-Trøndelag Elektrisitetsverk) and is part of a single-circuit 132 kV powerline running from Buksefjord hydroelectric power plant to Nuuk.The span consists of four steel conductors of 40 millimeters diameter whereby one is a spare conductor. The span has a width of 190 metres and a minimum clearance of 128 metres. The pylons on each side of the span carry only one conductor each and are situated on mountains 444 metres high on the north and 1,013 metres at the south shore.https://en.wikipedia.org/wiki/Yangtze_River_power_line_crossingsThe Yangtze River power line crossings are overhead power lines that cross the Yangtze River in China. There are at least three power line crossings on the Yangtze River at Jiangyin, Nanjing, and Wuhu. The towers of the crossing in Jiangyin are among the highest in the world. It is a section of the 500 kV power line from the Yancheng power station to the Dou Shan substation in the province of Jiangsu. The power line section running over the river has aspan width of 2,303 m(7,556 ft).= = =The tallest tower:The 380-metre tall electricity pylon to carry power cables between Zhoushan's Jintang and Cezi islands with aspan of 2, 656 metres= = = = =in the Pearl River, at<coordinates>113.5607734397952,22.88809827504799</coordinates>there is a tower in the middle of the river and the span on one side is 1555 m.

author: Gyro
author_rank: Super Contributor
timestamp: September 24, 2023, 12:26:05 pm
content: This is not a record breaker, at a span of 3060ft,with towers of 487ft high and minimum height over the river of 250ft, but an interesting article from my mid 1930s "Wonders of World Engineering" book. The span was constructed over the river Thames at Dagenham (also the site of the Ford UK car factory) in 1932, during the construction of the UK National Grid. The article includes some photos of working practices of the time - for instance, the petrol driven winch sitting on baulks of wood near the top of the tower, working in white shirt, tie and braces and working at height with little protection. It's hard to see how much PPE was in use (other than a cloth cap!), particularly harnesses, unless they were tied on by their tool belts...P.S. After several attempts, it seems impossible to get the forum to save the attachments in the correct order!

author: soldar
author_rank: Super Contributor
timestamp: September 24, 2023, 09:36:26 pm
content: Quote from: Gyro on September 24, 2023, 12:26:05 pmThanks! Very interesting.

author: IanB
author_rank: Super Contributor
timestamp: September 24, 2023, 10:10:27 pm
content: Quote from: Gyro on September 24, 2023, 12:26:05 pmIt's interesting that you posted that, since when this thread was first started I went looking for it. Unfortunately, I think it is not there anymore at that location.There seems to be a new crossing now, further downstream between Thurrock and Swanscombe. It can be seen at the link below:https://maps.app.goo.gl/KCzBb697UbxiPNsh8

author: floobydust
author_rank: Super Contributor
timestamp: September 24, 2023, 10:19:41 pm
content: I worked in the utility industry and some powerline runs had problems withconductor gallop.Usually in flat areas, the plains with no trees to break the wind. You would get phase-phase arcing or shorts if the lines touched and welded, or just fatigue failures of the lines.The cable segments between poles has many mechanical resonances. Adding mechanical AC termination resistance like aStockbridge damperor plastic spacers was done to stop it.

author: Gyro
author_rank: Super Contributor
timestamp: September 25, 2023, 08:52:25 am
content: One thing that did strike me when I was re-reading the article before photographing it, (in page 3) was the conductor composition:QuoteThey seem to have gone to extrodinary efforts and cost with these conductors, verging on unobtanium. If the crossing was indeed replaced with one downstream (rather than duplicated), the scrap value must have been rather lucrative (after a rather long unwrapping session)!I wonder what other long span conductors are made of, it seems unlikely that they would be of the same detail and composition.

author: soldar
author_rank: Super Contributor
timestamp: September 25, 2023, 10:30:21 am
content: Quote from: IanB on September 24, 2023, 10:10:27 pmI would think there's a good chance it was destroyed by that specialized German demolition team, the Luftwaffe.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 25, 2023, 02:20:59 pm
content: Quote from: Gyro on September 25, 2023, 08:52:25 amAFAIK nowadays it's a steel cable core surrounded with strands of aluminium, calledACSR (Aluminum Conductor Steel Reinforced).

author: Gyro
author_rank: Super Contributor
timestamp: September 25, 2023, 06:10:55 pm
content: Quote from: soldar on September 25, 2023, 10:30:21 amI'm not so sure about that. Hitting the fairly widely strung conductors and narrow steel lattice pylons would have been no easy task, short of a direct collision. The pylons were also designed to withstand breakage of 3 of the 6 conductors. Much larger targets were missed. I wonder what sort of conductors are used on the new crossing. Probably something much more boring like Steel / Aluminium as DavidAlfa says.EDIT: Checking the web, there is some general information. The new (Thurrock Swanscombe) crossing was errected, predictably, to increase operating voltage to 400kV, up from 132kV on the Dagenham one, in 1965. The new pylons are 190m (623ft) high, with a span of 1372m (4501ft). Minimum headroom dropped by 1ft to 249ft. The Dagenham crossing was only dismantled in 1987 (they missed!)...https://en.wikipedia.org/wiki/400_kV_Thames_CrossingThere's also a list of spans link on the page...https://en.wikipedia.org/wiki/List_of_spans

author: tom66
author_rank: Super Contributor
timestamp: September 25, 2023, 06:51:20 pm
content: Quote from: The Electrician on September 16, 2023, 02:14:06 pmThere's some very impressive power poles that bridge the Bosporus in Istanbul (I was there recently):https://www.google.com/maps/@41.0804261,29.052722,3a,61.3y,190.55h,94.25t/data=!3m6!1e1!3m4!1sNXJvucTIyyApaO7BfLwGPg!2e0!7i16384!8i8192?entry=ttuAlthough it looks like it is only about 1km apart, it must be quite a challenge with the strong winds here and keeping it away from the tallest ships (60m above the waterline from a quick Google as plenty of cruise behemoths pass through this area). I wonder how much it sags under high temperatures when all the air conditioning is running.Also there's these, which I accidentally saw on a trip to Spain, I think about 2km apart:https://en.wikipedia.org/wiki/Pylons_of_C%C3%A1diz

author: soldar
author_rank: Super Contributor
timestamp: September 26, 2023, 09:10:08 am
content: Quote from: tom66 on September 25, 2023, 06:51:20 pmInteresting. I had never known of this. 1660 m, just over one mile. I find it amazing that in the decades following WWII the entire western world did so much building of infrastructures and now it is like we cannot even maintain it.

author: .RC.
author_rank: Frequent Contributor
timestamp: September 26, 2023, 09:43:38 pm
content: Quote from: soldar on September 26, 2023, 09:10:08 amI am in the same boat. I look at what was built just in my part of the world in the post WW2 time period and then in the past twenty years the crumbling infrastructure it not replaced as it is "unaffordable" despite being built when the country/state/county/shire was far less wealthy.My theory is these days in first world countries, there are fewer people doing the real work of engineering, and actual construction and more and more people with clip boards going around saying I do not know what you are doing, but my book says you are doing it wrong. In general people who goal it is to make things more expensive via regulation.

author: soldar
author_rank: Super Contributor
timestamp: September 26, 2023, 10:32:37 pm
content: https://en.wikipedia.org/wiki/Greatest_GenerationThe Greatest Generation. They grew up during the Depression. They won WWII. And those who survived returned home and built and rebuilt their countries to prosperity and raised families.Later generations, all we know is to complain and criticize about how wrong our ancestors were about everything. Of course the world and the culture changes, as they should, but it is useless to focus on our opposition to the old instead of uniting and building the new future.It seems to me this decadence is general to western countries which are more divided than ever and with a very short term outlook. It is a shame because people would listen to a responsible and inspiring leader but we prefer to bicker and argue irresponsibly without regard for the future. We are wasting our time while our Titanic is sinking.I am reminded of Paul Simon'sHave a Good TimeYesterday, it was my birthdayI hung one more year on the lineI should be depressedMy life’s a messBut I’m having a good timeSo God bless the goods we was givenAnd God bless the U. S. of A.And God bless the standard of livin’Let’s keep it that wayAnd we’ll all have a good timehttps://www.paulsimon.com/track/have-a-good-time-2/

author: Someone
author_rank: Super Contributor
timestamp: September 26, 2023, 11:20:15 pm
content: Quote from: tom66 on September 25, 2023, 06:51:20 pmThe tension termination/blocks are frighteningly slender for such a grand span.

author: tom66
author_rank: Super Contributor
timestamp: September 27, 2023, 05:31:57 pm
content: Quote from: soldar on September 26, 2023, 10:32:37 pmIt's crazy if you think about it isn't it. In the UK we have a project called High Speed 2 which aims to build a rail line from London to Manchester (~200 miles). It's going to cost an estimated £70 billion if it ends up going ahead in full! Meanwhile the French have built similar rail lines for a tenth the price. That's not to say that French engineering is miraculously more cost efficient when some of the rail lines the Victorians built with hitherto-unknown processes were built (in real terms) for even less and are still operational today. There is a big problem in large-scale infrastructure costs where legal bullshit, compliance, environmental paperwork etc. just gets too big and bogs the whole process down completely in the mud. It's almost as if some people's entire job is to generate more work for themselves. There are environmental campaigners who are pushing heavily against the project, they do not seem to be able to see the trees for the forest, the line will have immense environmental benefits by taking a huge number of cars off the road (and even some flights). But oh no we have to tunnel under this ancient woodland because the great spotted newt was once seen here a decade ago. It makes me despair sometimes.

author: TimFox
author_rank: Super Contributor
timestamp: September 27, 2023, 05:35:38 pm
content: An excellent recent book on what works and what can go wrong with large projects:B Flyvbjerg & D Gardner:How Big Things Get DoneCurrency (2023).

author: themadhippy
author_rank: Super Contributor
timestamp: September 27, 2023, 06:38:29 pm
content: Quote£50+billion(rolling stock not included ) to save 30 minutes travel time for those fortunate enough to be able to afford a ticket,fantastic value for money,especially compared to the £4.5 billion the 260 miles of railway through laos cost,although it did take them 15 years talking about it before getting the shovels out and 5 years of digging before the trains started running.

author: Gyro
author_rank: Super Contributor
timestamp: September 27, 2023, 07:47:23 pm
content: HS2...

author: IanB
author_rank: Super Contributor
timestamp: September 27, 2023, 10:40:02 pm
content: HS2 is probably costing too much, but if you travel on some of the tiny, cramped, winding tube lines in London like the Piccadilly or the Bakerloo, and then travel on the Elizabeth Line, you realize what a difference a century makes to the state of railway engineering. When HS2 is eventually open, it will most likely make the WCML also show its age.

author: tom66
author_rank: Super Contributor
timestamp: September 28, 2023, 08:06:25 am
content: Quote from: IanB on September 27, 2023, 10:40:02 pmThough the WCML was substantially upgraded in the '00s to the tune of £10bn which allows it to run at 125 mph. Whilst the track alignment and some infrastructure like bridges and tunnels are original, a lot has been upgraded.HS2 is essentially bypassing WCML because WCML is at a total capacity crunch and can't support stopping services and high speed traffic at the same time.