Yes, I know that a UK domestic single phase mains supply is ~230V. This is one phase of a 3-phase supply which runs along the street. The voltage between phases is ~400V. It is this voltage which should be compared to power line voltages, which are measured between phases. Alternatively you could say that a 400kV power line is actually 230kV from any phase to earth.
Now we start to get a bit technical ...... The 400kv power lines are actually connected in delta format! It only goes into a star format at the substation giving out 240/415 V! There is an earth wire running on top of the normal (UK) pylons but that is more about stabilising the voltages at each end rather than letting it float.
@@totherarf the earth wire above the power lines is only for lightning protection. You are correct that transmission is delta, so the line voltages aren't defined in relation to earth. But after speaking to engineers who know more than me the concensus (so far) is that the various leakages will in practice give similar voltages to earth as star/wye. All info for illustration purposes only, I take no responsibility for anyone trying to build their own grid or climb a pylon with a multimeter on the strength of a youtube video, etc etc ⚠️
@@martinalooksatthings Not Only for lightning protection although it may vary between countries. You can get a surprising difference in voltages relying on the mass of the earth to equalise things. I must admit my experience is only from the substations and the distribution network not HV. One of the detection methods for HV tripping on pylons is the detection of current running through that earth wire.
oddly, as a sparky, we rarely see true 230/400, it's still usually around 240/415... the change was nominal.But some very modern developments have true 230/400
I lived in a flat years ago in a formerly industrial area. I think the local distribution was geared up for heavy loads because I regularly got 250V+. I had a couple of PSUs in things die
I used to despise pylons and the way they ripped through the countryside, however as I have come to realise how important electricity is to my life and am now aware just how impractical it is to bury the cables I have grown to appreciate the role pylons play and look beyond them.
It's amazing how understanding a thing can change your appreciation of its aesthetics. If the underlying engineering of a thing is beautiful to you then it's almost impossible to find the end result ugly.
I wouldn't say burying cables is 'impractical' (at least for 132kV and below), it's just very expensive in comparison to overhead. I've just had a 5-circuit 132kV set of lines installed past my house and it was an impressive amount of work spread over about 2 years - you can see why it's expensive. Lattice pylons are butt-ugly - I can see why people complain about them. I too understand the importance of the grid and further decarbonisation, but it doesn't make me think pylons through the countryside are at all aesthetic. The new ones a big improvement IMHO.
Oh no, don’t want to open pendantry corner but Tesla did not invent 3 phase. He invented Poly-phase or 2 phase. Which requires 3 wires. Mikhail Dolivo-Dobrovolsky invented 3 phase that could carry an additional load phase and still have only 3 wires. Anyway don’t want to be boring just don’t Dobrovolsky gets the credit he deserves. Great video as always, love to see videos on something that is so important but often overlooked.
Also I really like the new pylons going across Sedgemoor, I think they look ace. I googled them after I first saw them and apparently they take up less farm land, win win.
@@martinalooksatthings Indeed, more follows. Tesla's great achievement was creating an AC motor that gave Westinghouse a huge advantage over Edison. Along with AC's easier transmission, voltage transformation, and grid-forming capabilities, Edison's DC system never really stood a chance. And yes, even today in the industry they are still called towers, only the general public refers to them as pylons so it was lovely to hear you get that all straight 😀
@@martinalooksatthingsAnd… is not the supply to a domestic house in Britain usually single phase 240 V or thereabouts with current limited to no more than 100 A? As both current & voltage are ac, these values are root mean square ones, peak-to-peak values will be higher but probably only of interest to designers of insulation & air gap clearances?
Interesting that the cost of these transmission lines is never discussed. $/km. Total replacement costs is $TRILLIONS and decades and decades of construction time. They are often 'invisible', including the distribution lines in the streets. Nobody notices them after a while.
@@stephenbrickwood1602 do you mean total cost of the network when you say replacement cost? The thing about the £/km is that it actually decreases as the length of the line get longer, because of all the switchgear and protection systems etc is a good proportion of the cost of the line - as the line gets longer the cost of this equipment is spread out over more km of conductor and therefore the cost per km decreases (obviously the overall cost of the line increases, but at a decreasing rate per km as the length increases) - and then you have factors like river crossings and diversions around beauty spots or other major infrastructure to consider - it's certainly not a "Xkm = Y£" conversion :) We just got approval for a 500km HVDC undersea cable on the east coast of the UK, total expected cost around £3.5Bn including risk pot :)
@@martync6713 yes good comment. Terrain, distance to support towns, switchyards and land costs and huge numbers of variables. In Australia $5 to $6 million per km for 990km and 1,000km lines. Nuclear promoters refer to $10million per km and more. Let me say increasing grid distribution capacity in city and town streets that are busy daily with pedestrians and vehicles traffic and need electricity power to homes and refrigerators etc.means late night shift work. Maybe new poles. And upgraded homes and buildings connected. So even this work gets surprisingly expensive. Contractors tender prices are painful. Most people do not think about the existing investment and cost to expand. Or maintenance and out off hours emergency work teams on call.
@@martync6713 these matters are important or the vested interests will hijack the process. Nuclear promoters in Australia have politicians promoting government construction of nuclear electricity and monopolising the grid. Government guaranteed cash flows will happen. Rooftop PV disruption to the grid supply us being charged $kWh on feedin, or to be implemented now.
as you're a grid engineer, can you tell me one thing, i live locally to the IFA2 convereter station at peel common, lee on solent... what was the reasoning for doing this rather than reusing the existing infrastructure feeding the now sadly defunct fawley power station the other side of southampton water? (if you know). Fawley has (sorry had) interconnects to Chilling and Nursling, and was rated at 2000Mw, more than enough? Edit i believe it still does HAVE the interconnects, just there's no power station there anymore, god i miss that chimney on the skyline
For long distance transmission lines, it is necessary to transpose the position of the phase conductors two times on the pylons, so that each conductor occupies a different position for a third of the total line length. This is done to balance the inductive and capacitive reactance .
Called a Transposition Tower. We (CEB/CEGB/NGC) used to have them on the 132kV transmission system back in the day when the early days when the 132kV was the main transmission system, before the introduction of the 275kV and 400kV systems. The towers are still in use and viewable, they have very long support arms than the usual suspension or tension towers.
@@stevesteve8098 Mishaps occur but then when the contractor is clever mistakes do not occur. In any case , the line is energized at one end and phase order is checked at the other Fixing an error is not difficult.
As an ex NGC employee, CPS, SAP, AP, CPIC & live Linesman, I can see you have done some really good and thorough research. Well done. BTW All things with wires within them will fail when within 1m of any bare conductor of a live 275~400kV OHL Cct. I know from experience
My favourite trick (domestic/light commercial electrician) is to hold my volt stick under the 275kv lines passing over our local wholesaler's building... my entire van reads live when parked underneath. Fun anecdote, they're meant to get the line isolated before working on the roof, some idiot scaffolders didn't follow that, and one dude got quite a jolt waving a 5m scaffold pole around on a damp day, stood on the roof. Dude didn't know how close he came to becoming charcoal!
@DroneLearner Any gas including air is ionized by the electric field that surrounds the conductor. When the field reaches the point of "dielectric rupture" the ionized gas becomes a conductor and a flash to ground or between conductors takes place. If the air is humid or it rains the dielectric breakdown occurs at a lower voltage than under dry conditions.
Well. I thought I was going to bored with this but no! As my Dad worked with the CEGB/Grid and did a lot of work in Germany post war this was quite interesting. He used to supply industrial switchgear and helped design power supply set ups and distribution. Where I lived in rural Norfolk for a while we had a huge pylon at the end of the road and we all liked it was annoyed when they wanted to move it. Those familiar with Bedford will know the old Igranic Works that became Brookhurst Igranic that made huge contactors and swing rotary open switches for power stations. As a kid I often went with my dad "on calls" to various power stations including the new hydro ones in Snowdonia. He went on to invent colour proximity sensor equipment and pioneered heavy electrical equipment. He was a child of Aston University that was the main uni for electrical engineering. After he graduated his first job was in Germany to rebuild the power grid after the war. He worked with AEG(Telefunken), Siemens, Brush, the then Cutler Hammer, GE and Whetstone. I remember as a kid playing with all the equipment lying around the house. During the power cuts in the 1970's we were the only house in village that electricity as he ran a system from the Ford Cortina to an inverter and powered the house! At one point the local doctor took over the lounge as a makeshift surgery. I recall him rewiring the house and every wire, clip, JB and ChocBox had to exactly in the right position and the wiring out of the CU was a work of art!
@alantheskinhead I am not British but I do remember from my early engineering years the excellent (but very heavily built) equipment made by English Electric, the GEC under Lord Weinstock, Reyrolle Parsons very old switchgear cells made with masonry cells and Metropolitan Vickers equipment that was amazingly sturdy
Great video. Subject matter brings back memories of my young niece pointing to every pylon on the way when I picked her up to stay for the weekend. As we drove past power substation by Spaghetti Junction, she'd always shout, look aunty, power station. She was then, as she is still fascinated with pylons and all things electricity.
@Andrewjg_89 In the US where forests of high trees grow, wooden pylons properly treated against rot and insects are used for quite high voltage transmission lines while the French have perfected standard concrete pylons (with steel bars reinforcement) for distribution of power in mostly rural areas.
Thank you for the education and information . I didn't know how important pylons are, for transmitting electricity around the country, absolutely brilliant and aesthetically beautiful .
I cannot understand how the British can hate pylons so much, calling them 'a blight on the landscape'. In Zimbabwe we would welcome the installation of pylons and the connecting electrical grid because it meant bringing electricity to remote rural areas.
As you said in the video, the number of discs of the glass / ceramic insulators depends on the line voltage. As a minimum, we use one disc for every 11 kilovolts of line voltage. There can be exceptions if the line is close to the sea, where more discs are needed. You mentioned high voltage underground cables, costing - per kilometre - ten times the cost of an equivalent aerial line. That is a minimum, the price is usually higher. Also, being the HV underground cables being filled with dielectric oil, they are very hard to maintain in case of failure. Thank you for the video. Anthony
@@Eddiecurrent2000 Correct, I doubt that manufacturers today would supply oil filled 400kV cables. All would be XPLE as you state. INdeed in the 1960s there was a section of 275kV XLPE cable installed on a circuit in a North London Substation.
Yeah. Underground might get used through national parks (Dinorwig) but it is hugely expensive. I don't know how the costs of subsea HVDC compare though. There's already one from Scotland down to North Wales and Eastern Green Link 2 is now a go to take power down to near Drax.
it is actually simple maths. most domestic and loght industrial 3 is suplied at 415V phase to phase. . domestic suplies are 240 phase neutual.. phase phase is phase neutual x sq rt 3.so 240 x 1.732 =415. there is a proof to the fomular but cant be bothered to look it up. Modern domestic suplirs are 3 phasa cables with each house phase neutral first house red, second yellow third blue fourth red. y b , ryb etc Dave NG R3TIRED
@@Threelinkdave For the most part in my observations jointers usualy connect to the nearest phase after stripping the cable, thats my experiance working in distribution for 35 years - retired.
Came to the comments for this - and mike has won the prize 😁 Great aerial shots however and love the facts - I did a stint at National Grid as work experience many years ago - I have a National Grid mouse mat right next to me 😆
Just discovered your channel, and addicted already. Very well researched and presented. Much appreciated by the engineering buff whose family originally came from Birmingham.
UK electricity demand is actually dropping, mainly due to efficiency improvements, in 2012 it was 318TWh but by 2023 it was 250TWh. So despite there being 1 million EVs on the road, there is plenty of spare capacity at the macro level, it's just that more and more of the generation is in Scotland and the far North of England. People in the South East complaining every time that someone wants to build a solar farm or wind turbine are being the ultimate NIMBYs, most of their power has been generated in the North from coal, but because they can't see that, and it only affects Northerners, they think that they have a right for this to continue. Love from an anonymous power engineer.
@@teresashinkansen9402 It is significant. My parents used to run 6 x 100 watt bulbs in their living room, those have been replaced by 6 x 7 watt LED with no loss of lighting. Lighting is key, shops used to run hundreds of 50W spotlights, most of those are now 3 or 4 watts. The other household advances are mainly TVs and fridges. Most 50 inch flat screens are running at 150 Watts, the equivalent 32 inch CRT was 800W, a 40 inch plasma almost 1000W.
Mary had a little lamb, she tied it to a pylon, ten thousand volts shot up it's a*** and turned it's wool to nylon. Good to see you back, is it time to have another look at the HS2 around Birmingham?
Tower fun fact is that the nut is on the lower part of the bolt on the bolted joints. The thread is centre punched so the nut can not unwind as the lines vibrate in the wind. If the nut came loose and dropped to the ground the bolt would remain in place under gravity. Still in the bolt hole of the components of the bolted joint. I inspected 840 towers on a 1,700 tower line.
I'm from West Yorkshire we have just about every variant of pylon somewhere around here. Thats a legacy of our industrial heritage and the fact we had/have a rich supply of coal and thus generated a LOT of power for the wider UK, although most of the coal plants are now demolished. There are some of those "PL1" towers a few miles from me, I was driving past them just this afternoon, quite sobering to think the design is now nearly 100 years old! I have some of the ceramic and glass dish insulators from when they were replacing some local 33kv / 66kv lines near me a couple of years ago, people are always surprised how nice they look when they see them up close, they are heavy though!
In the late 1970s there occurred a major blackout along the south coast of England in an incident which doesn't seem to have made the normal reference sources. It was, as these things often are, a combination of circumstances. It all started late one summer's morning when one of the supergrid transfomers at Feckenham, south of Birmingham, failed. That took out the 400kV circuit which goes via Minety to Melksham. (The remaining Feckenham southbound circuit goes to Walham near Gloucester.) Melksham is one of a series of grid substations broadly along the M4 corridor. It stands at a "crossroads" and much of the power for the south coast of Dorset, Devon and Cornwall in those days was kept going by that link with Melksham feeding Exeter via Hinkley. Coincidentally, though, half of the 400 kV circuit from Canterbury going round East Kent to Lydd was down for maintenance and some silvering of the pylons, so capacity was really reduced and not much extra could be drawn round from there. It was before the days of the Sellindge converter and the DC links to France. The only other link from the M4 corridor to the south coast was the twin-conductor double-circuit line from Bramley via Fleet to Lovedean. The circuits along the south coast were all quads and expected to be high capacity. That Bramley-Lovedean line was put under maximum strain trying to compensate for the loss of both Feckenham-Melksham and half of Canterbury-Lydd, and it also quickly tripped out. It was summer. Generative capacity along the south coast was seasonally reduced, much of it still using coal, and it would have taken days to get that up and running. The result was that from areas like Fokestone west through Brighton, Portsmouth, Southampton, Bournemouth, Weymouth and almost to Exeter there was no power for almost 8 hours. It was before the days of people having PCs or being personally dependant on electronics, so there was far less public consternation about it than there would be nowadays. We just shrugged our shoulders! At least central batteries and generating sets kept the plain old telephone system going.
Thank you very much for that. I was living in Folkestone at that time so must have been affected by the power failure, but don't remember anything in the news about it. I do remember blackouts as we had things such as the three day week then, but being a child it was an adventure having a power cut in the evening meaning we had to use candles to see with.
@@bernardm2312 I may be wrong in that Folkestone at the eastern end of the problem area probably drew its power from the 132kV network and was close enough to the fully-connected Canterbury site not to have suffered too badly, but I only ever found one reference to this incident in an academic paper a year or so ago (I must try to find it again!). I thought I must have misremembered it all, but I do recall the late evening TV news (by which time we were back on supply near Bournemouth) trying to give an explanation. But, ah, the 3-day week and rota power cuts 1973-1974. Knowing that you stood a 75% chance the lights would go off at 6pm for 3 hours. Did you know there's still a provisional system for a whole series of gradated regional cuts should generation be in short supply? The Electricity Supply Emergency Code. There's something like 18 stages before it means everyone is off the whole time.
I think the incident you are referring to was in August 1981. I was working in the industry at the time and took the afternoon off work to go and buy a new camera. I drove about an hour to the shop where I could get the camera that I wanted, only to find they had closed due to a power cut.
@@stationmaster5628 Ah, thanks for that. You could well be right, as I wasn't regularly in the Bournemouth area until 1980 and thought I must have been on one of my frequent earlier visits. Strange though that with such a widespread outage it gets no mentions anywhere. I would hope that it couldn't happen now with 4 international interconnectors coming into those zones, and the south isn't a region so dependant on former generation centres like the Trent "Megawatt" Valley plus gas turbine and green generation now dotted around the area in the geographical mix.
@@heckelphon It shouldn't have happened then. It was two separate coincident faults that caused the third to happen and cause the blackout. It was pre computers and pre privatisation so all records are in paper form in an archive somewhere so nothing to publish on the internet. It would have been in the newspapers the following morning so might be in one of their archives if they are on the web.
If Tesla's design had gone according to plan, three-phase current would have 6 cables today. It was the Russian Mikhail Doliwo-Dobrowolski who introduced three-phase current with 3 cables in Germany. In contrast to Tesla, he not only had a theoretical drawing, but was also able to demonstrate a functioning system with a three-phase generator, three lines and a three-phase motor. Tesla, on the other hand, insisted that it was the first to come up with the idea of 6 cables for three-phase current. Even Westinghouse built the system with only 3 cables, according to Doliwo-Dobrowolski.
I lived near one that buzzed when it rained.. what was going on as that was 20 years ago and it doesn’t buzz in the rain now. Great video finally all the things I wanted to know about them all in one place 🙏
Wow! The amount of research you must have done to make this video is commendable! Good job sir! Also, great drone footage and archive photos. I should mention to anyone who might think that flying a drone near 400kv might end in death for the drone, it won’t, because the drone is not connected to ground, so there is zero potential difference/ zero voltage difference. One could argue that if the power was to arc from the conductor cable, to the drone, then to a grounded/earthed steel support it would pass voltage, but it won’t do that because the spacing allowed between conductor and support structure has been carefully calculated. I think there is a general rule of thumb that for every 1,000volts of voltage differential, power can arc through 1mm of air, so at 400kv it can arc 40cm or so. Please correct me if I am wrong. I think I learnt that from Practical Engineering RU-vid channel. Anyway, massive thanks for the time you put into this video Jonathan
I understand the drone, I understand why birds can sit on the line. What I don't understand is when linesmen work "hot" why they have to make the helicopter part of the circuit while they climb onto the line? The helicopter isn't grounded so why?
@@hoojchoons2258 Rotating helicopter wings (rotors) can create a lot of potential due to static electricity effects. How much depends on speed of rotation, humidity, temperature, a lot of things. That may be why.
@@hoojchoons2258 Because until they bond on, there is still a difference in potential even though the helicopter isn't grounded. Once they connect to the power line they are at the same potential. Then depending on the voltage they may still need to wear Faraday suits, since with high voltages there is still a gradient the further from the conductor you are. The mesh in the Faraday suit is conductive and helps stop any gradients. Even still, the guys I know who worked transmission lines hot said it still feels like something is crawling on you.
Great video! I have always been fascinated by pylons. On a windy day the insulators and conductors swing out to the side. On a frosty or foggy day you can hear the 400Kv sizzling across the spark gap to earth.
@DavidVR2 The sizzling is actually due to a ionization effect of the air around the conductor. The air molecules break down and start to conduct. When there is humidity, the phenomen is increased because humidity favors the conduction and thus the ionization
01:37 we don't have 3 phases "thanks to Nicola Tesla", but thanks to Friedrich-August Haselwander. Guess native english speakers can't say his name and ignore him therefore :-) Haselwarder built the first synchronous 3 phase generator, that was in 1887. Now, Tesla made something similar: he studied (!) multiple phase generators in 1882. And in 1887 he built one, too ... but only a generator with 2 phases. So we don't owe 3 phase generators on Tesla. Oh, and the first asynchronous 3 phase generator was built in 1888 by the german company AEG, here Michail Ossipowitsch Doliwo-Dobrowolski was the leading engineer. He was a russian that fled his country after the assisation of "Tsar" Alexander II.
My understanding is that the doubling of the conductor cables was to reduce the corona effect by increasing the effective diameter of the cable without adding unnecessary amounts of extra metal.
@heronimousbrapson863 It is mostly to increase the amount of power to be transmitted. It amounts to adding a conductor to an existing line and it is far cheaper than building a second line
Energis, a now defunct Communications company used the pylon network to carry fibre optic cables that were co-routed with the earth cable on pylons. A machine was developed to install the fibre that ran along the earth cable and wrapped the fibre around it in a spiral. The system was more resilient than underground fibre that was prone to people pouring petrol into Energis access covers and setting it alight in the hopes of burning away insulation so they could pull out the copper they expected to find to sell it for scrap.
The optimal solution is a direct swap of the coal generation facility for a BESS facility. It makes total sense indeed, especially saves money and eliminates a zillion tons of coal-burning waste.
They're in the process of removing a string of pylons & burying the power lines near Black Down in Dorset, expensive yes, but the subsequent works have uncovered Prehistoric archaeology not found before & the now uninterrupted views are refreshing to see.
I remember as a young lad looking out the car window as we passed by pylon after pylon, and I imagined some poor sod spending his life bolting those things together.
The number of the conductors for one phase in one circuit has not only to do with the current, but also much with the voltage. The keyword is "corona discharge".
It’s a small price to pay go have electricity on demand. Living in the old generating capital of the country we have pylons everywhere, most people don’t even notice them, not like wind turbines and solar panels
Where I grew up, there was a 'Project UHV', where they had a few massive pylons out in the middle of nowhere, ad were testing new designs.This was in Lenox Massachusetts at the Pittsfield border.
What I found interesting is the high voltage lines running directly over apartment housing. In the US, you rarely (if ever) see that. I suspect it's because of the lawsuits regarding stray voltage and farms (had to do with milk production and the negative effects of the stray voltage - that could be a great video, too).
This subject always fascinates me as my dad worked on overhead lines for most of his career. His last job before retirement was Chief Training Instructor at National Grid's National Technical Training Center in Hams Hall (the one on your map in the video). Hams Hall has long since been shut down and sold off and it's now a business park. Also, I've have noticed in recent years that some L6 quad lines have been converted to from quad to triple cables with triangular spacers. I'm not sure why or whether this changes the capacity (with thicker cables?), but it's a definite trend that I've noticed on lines running though the Pennines.
@@heslop1brian Yes they were. As I recall there was a pair of short 275kV (or maybe 400kV) towers cabled up and with full insulator sets to support insulator and spacer replacement training but at a relatively low height.
more wires on same phase is also used to reduce corona discharge effect. Thats why 400kV lines always use 3 or even more wires per phase. For example, here in middle of Europe is often in use this configuration - 1 wire per phase 110kV, line, 2 wires per phase 220kV line and 3 wires per phase 400kV line.
Also "skin effect" - that current mostly travels on or near the surface of the conductor as well as to reduce coronal losses. These days the 400kV supergrid favours 3 conductor bundles. The exact reasons are, I'm told, classified, but it shouldn't be too hard to tell why given the well-understood physics and mathematics involved.
2:44 the UK mains voltage is around 230 Volt. Only the voltage between two lines of a three-phase system is around 400 Volts there, like in most of Europe. That's not what people usually refer to when they speak about their electrical power connection. A standard household power socket in the UK delivers 230 Volt, 50 Hz (single phase) power. Most houses in the UK will not even have a three-phase connection.
1:29 - 1:32 Wrong. Nikola Tesla did not come up with the three phase distribution grid that uses trhee wires. His systems were different and needed four wires or six wires depending on the specific polyphase system. The three wire AC the world uses was developed by Galileo Ferraris. Mikhail Dolivo-Dobrovolsky also studied delta and star connections and created three phase transformers and squirrel cage induction motors. He designed the first three phase hydroelectric power plant.
Nice. The cables are also interesting. Apparently the latest composite cored cables can carry double the current for the same sag extending the life of existing pylons.
A bundle of two or more conductors are used on lines whose voltage exceeds about 150kV, so as eliminate corona discharge. Said discharge wastes energy and generates radio interference. For ultrahigh voltage lines, the bundle may comprise six or even eight conductors, separated from each other by spacers. The total cross-sectional area of the conductors is increased, but at lower voltages, the wire gauge can be increased, achieve the same result.
I have grown attached to pylons over the years observing them stretching across miles of open land. Each one leading to another and then another to an unseen destination hundreds of miles away. So many stories - who services them, tends the land around therm. As for their construction in days before Health & Safety legislation one marvels at the dexterity workmen shuffling top the top. Yes I think I would miss them but I would not want one in my garden. Those that do should at least have the perk of free electricity.
Actually most ACRS conductors designed for electric grid are rated around 500, 1200, or 1800 amps, with 2500 amp feeds generally using dual 1200's (and while rare, some triple conductor lines exist; more common to go to more separate feeds then, easier for maintenance and management). Power is Sqr3 * I * E for PF1 3 phase, and since I^2R heating limits current, power capacity for lower PF degrades. Currents are nominal and overload ratings are used at times, in brownout conditions, but a 500 amp ACRS 477 conductor operated at 800 amps temporarily doesn't just droop more, but has metallurgy permanently damaged, reducing the long term life of that conductor, at high potential cost. That also means that a safe, long term repeatable current rating is more realistic, than an extreme overload rating that won't fail, but will cause irreparable damage.
Thank you, very interesting. I recall reading in the year 2000, soon after the debacle of the New Year Eve 'fun time' at the Millenuim Dome, some one suggested a better spend would have been to use the nearly £1Billion pounds to have used it to bury the country's overhead cables all underground. The Dome cost £789 million (£1.73 billion in 2024 pounds)
They're currently spending half a billion putting a small number of power lines underground, burying ALL of them would take more money than reasonably exists
I had one in my garden, one thing you don't mention is they are noisy, especially in fog. We also had several lighting strikes on it. Can't say I miss it.
Great video. I wish you had given dates. I am a retired engineer from CenterPoint Energy aka, Houston Lighting & Power. Their system dates back to 1882 in the Edison DC era. We don’t use the word pylon. As one of the company’s former historians of their transmission world, the earliest “lattice tower” I found in their system is a borrowed design from the telephone company and it was attached to the Galveston Causeay railroad bridge and was constructed back in the the mid 1920’s. The latice tower created the need for new types of foundations because you could not install the using the old wood pole method. I wish you would make a video on the unseen part of the “pylon”, the foundation, and all of the highly technical issues involved and the development over time. It would be a great comparison between countries and how technology is transferred from place to place.
Indeed as a former National Grid employee we used the term Transmission Tower. Pylon is the common word in the UK used by the general public. A bit like using the term gasometer for a gas holder site.
@TexasEngineer A pylon is a tower here in Dallas. As a matter of fact (and personal taste) the lattice structures are nicer than the round pylons/towers. I once had an assignment in North Africa and the LOCAL CONTRACTOR had the foundation prefabricated offsite. A big concrete block with four galvanized steel stubs sticking out at an angle. A hole was dug and the whole package was lowered carefully for precise alignment. Once the hole was filled with sand and concrete and the foundation levelled, three other tower sections (preassembled) were delivered. The first section was hanging from a crane and pushed and shoved till it matched the boltholes on the protruding stubs. The rest went easy. Off subject: Watching on Internet the Ercot meeting with Centerpoint, it was strange to hear the utility people concentrating on the need to remove vegetation under the line as this was THE ONLY problem to be resolved.
Back in 76/77 I was lucky enough to fly in a new 206B Jet Ranger used by the YEB to video infrared images of pylons and lines looking for leaky insulators. The pilots name was Bob Jones. #goodolddays
Notice that some of the top cable on some pylons has a twist which is due to a fibre optic cable using the infrastructure to deliver the internet! Sky uses this as their backbone run by National Grid in many parts of the country.
Cool video, liked and subbed! Have recently been more interested in pylons (no idea why), and was trying to look for any books on their history etc. This video was very interesting and scratched that itch! If you have any recommendations based on your research please reply and let me know! I just wanna know facts about them. The bit about angled pylons made sense but I never thought about it before, I thought all pylons were just the same. My background is in maths, not engineering, and ironically my least favourite part of physics was always electric engineering, or anything with circuits, but maybe I should learn! Also where is that cool electricity gridline map from?
There is another reason for the truss structure. It uses the least amount of material for the size of the unit. This goes along the the light weight aspect for assembly.
Our L6s in southern hampshire now use a triple conductor, each one thicker than the 4... apparently this increases capacity without needing to rejig the pylon itself
they did replace the glass/porcelain with polymeric insulators tho, they're SO skinny, there's one on the M271 that has the old glass insulators on one circuit, and polymer on the other.... very eye catching for a geek like me
@TheChipmunk2008 Sort of. The pylons are subject to additonal stress due to extra conductor weight and wind forces on the conductor , weight of snow or ice on the conductor etc. So, most likely the pylon was sized already for the additional cable and that is what avoids rejigging or modifying the pylon
@@pindapoy1596 These pylons date to the 60s... but yes I am sure they did all the calcs. It was quite interesting watching them haul the new conductors up. I noted they were working on one side with the other side still live. They had heavy earthing attached to the sheaves to limit the danger from induction
@@TheChipmunk2008 How do you know that the other side was live (energized)? It seems to me to be quite hazarduous if a worker extends his arm even without touching the other side. I have seen all the contrary; the three conductors joined temporarily with short pieces of cable and bolted clamps and one downcoming conductor attached to a steel stake hammered into the earth at the foot of the pylon. That is done even on the circuit that is not worked on. The reason is that far way, a lightning strike may hit the line and bring the voltage on the conductors (for a very short time) to an extremely high voltage level. In the mountains, atmospheric discharges occur even when the sky is perfectly blue. No lineman will ever climb a pylon without having verified with his own eyes that the circuits are fully grounded. If the line is already connected at one end to a source of voltage, the safety agent will padlock all circui disconnecting means in the open position and keep the key in his pocket (or in a locked box) whose key is in turn kept by the agent. Some of these safety procedures can be quite complicated and lenghty and often reviewed by a committee before the work starts.
I do small pylons that have such character and they look like people. The UK does have the best and weirdest pylons. But other countries do like having pylons and how they maintain them with care.
Fun fact: Pylons/Transmission Towers are painted yellow before the grey is applied. The reason yellow is used is that it is the primer and it becomes very noticeable from the ground or air when repainting of the grey topcoat is required. National Grid have their own helicopter fleet and one of their tasks is to fly along parts of the network to visually inspect the lines and towers (looking out for yellow paint showing through for example). They dont hang around either, the pilots are incredible, circling around the pylons as they go along the line - its really impressive to witness to be honest!
I'm curious about the physics of the 'lights' on sections of the power lines between pylons that I've seen in some places in France. They glow (by ionisation?) apparently without a return path.
@LostsTVandRadio There is a capacitance effect created betwen the conductor and ground . The two sides of the capacitor are (1) the wire and (2) the ground. Actually that capacitance can be calculated and measured in the field as microfarads per Kilometer For most line designs it is even tabulated in specialized manuals. And capacitors conduct electrical time varying currents (not DC)
What is the law in the UK regarding location of pylons and HT wires near residences? The mention of a pylon in that poor bloke's garden amused but concerned me. Thanks in advance for the answer.
The other thing is that the pylons are so large, the drone isn't actually as close as it might seem. They insulator strings only look small on the ground because they're so far away!
Interesting fact is birds do not like to sit on high voltage transmission lines. The static charge is uncomfortable. You will see them on the lower voltage distribution lines. They like the distribution lines in the winter because it will warm their feet. The temperature on the transmission lines can cause burns to bird feet. On very high voltage transmission lines, radio communication can be lost. I have been trapped under 345 kv lines and had to walk out to call for help because the 345 kV lines blocked the cell phone signal. I would expect similar issues with drones flying around transmission lines in that they would avoid going under the lines or out of direct line of sight with the controller.
awesome video, it's great to learn about the power grid it's not talked about very much at all! You might be interested in what's going on in east anglia with a lot of construction sites already appearing in norfolk
@@martinalooksatthings the main project that's underway atm is in connection with the Hornsea 3 offshore windfarm. I believe there's to be underground HVDC cabling from the windfarm through Norfolk to a grid connection in Swardeston just south of Norwich. That site will also house battery storage infrastructure. In connection to this Norwich substation (which is nearby) is getting upgraded with a few pylons to be replaced with underground cables to connect to Swardeston. A new transformer was driven there yesterday apparently. Another Hornsea 3 site is around the A140 at Aylsham - i've not seen much about what that's meant to be. Those two sites definitely are being worked on currently but I've heard of other smaller sites along the path As I'm sure you know, National Grid are trying to put a new pylon line in from Norwich to Tilbury but construction isn't planned to start until 2027 at the earliest
@@contrapunctusmammalia3993 There's a bit of controversy in this since they want to run it past some airfields, which would obviously be vary dangerous to aeroplanes.
I don't think overhead lines are disliked because of how they look, but much more because of the danger they pose. Aircraft, overly tall vehicles, trees... I get it, you shouldn't get into a bad situation with OHL if you're doing what you're supposed to do. But these accidents happen and keep happening and if the lines are underground, there is nothing to hit.
But judging from the noise, it seems the "look" is being protested. IMHO such protests are disingenuous; the deep-rooted motivation is hatred of technology and modernity. I have not encountered one single anti-energy opinion that has seriously raised a safety concern. Oh wait: Trump bewailed 100,000 birds killed by turbines - and forgot about the 50 million killed by cats.
Nice to see Open Infra Map being used. I've spent way too much time putting in overhead lines on that. Is there a place that grid mapping nerds hang out.?I often have questions about identifying 11 vs 33 vs 56 kV poles/circuits. transformer types etc.
You used to be able to find maps/diagrams from the distribution companies which usually showed 33kV and up, but I haven't found any lately. I have before added underground power cables to OSM/OIM point to point and been pleased to see that someone else had refined their route.
