Posted: February 14th, 2013 by tomabbott
Comments (44)

First prototype Suspension T-pylon erected

Central node supported by a crane and connected to the top section of the mast

Picture 1 of 26

We’ve reached a major milestone in the T-pylon project – the first full-size suspension pylon prototype has been put up and is ready for testing.

At the start of January a small team from National Grid (design, construction and maintenance) joined colleagues from the T-pylon’s designers, Bystrup, and DS SM (a Danish steel company – www.ds-sm.dk) to erect the first T-pylon. We, and our Danish partners, were keen to get an idea of where lessons could be learned in putting up T-pylons as we moved, for the first time, away from computer screens, scale models to a real-life installation.

The first observation was that, once up, the pylon looked really elegant. We were pleased with how amazing it looked in real life…sleek, slender and simple, a culmination of 11months of targeted activity. Accelerated development timescales meant that we chose to use uncoated steel for the structure, which just served to give the pylon greater charismatic appeal. The corroded surface appeared similar to weathering steel (e.g. Corten), the same material used for the Angel of the North sculpture. Weathering steel is a surface finish option, alongside painting, that we are considering for use with the final design.

Putting up the first T-pylon on a rainy and cold day in Denmark gave us lots to think about and has allowed us to make some provisional changes to how we are likely to proceed with designing and constructing future pylons. The main point, which greatly encouraged us on the day, was that a multi-skilled team of four people erected the pylon on its pre-installed monopile foundation in a single day.

On our test day, we were hampered by two 200 tonne cranes hired for the heavy lift malfunctioning. In the end we borrowed a crane working on a line for Energinet, the Danish Transmission System Operator we have been working with on this project. We lost a lot of time but still managed to get the construction work done in a day. When all is considered, this still compares favourably, in terms of construction man hours, to today’s lattice pylons.

Making connections

One of the main lessons we learned was that the cast iron cast connections (by Heger Guss, www.hegerguss.com) between the crossarm to the horn and crossarm to the mast, via the heart at the top of the pylon, are challenging and time-consuming to put together on site. The heart (five tonnes) and horns (one tonne for the pair) are made from cast iron and so are heavy and the hundred or so nuts and bolts which join them are each the length of a forearm and need to be fastened to a specific torque which can only be achieved in a tight space with a torque converter.

This can be a little unwieldy and so we’re actively considering having the crossarm, heart and horns pre-assembled in the factory. They could then be taken to site as two sections, saving a considerable amount of time. Furthermore, we’re seeking to redesign the cast elements with a different iron type and to have threaded holes alleviating the need for nuts to save material and weight.

The assembled crossarm (two crossarm sections, heart and horns) were then connected to the three section mast.  The three upright sections (top, middle and bottom) of the mast are slip jointed so they effectively just slot into one another and are jacked together pneumatically creating a strong interference fit to withstand design loads that could cause torsion or bending. The upper two sections (top and middle) were slip jointed horizontally on the ground while the lower joint (middle to bottom) was made vertically after the top sections were lifted into place.  Here again, putting up the prototype taught us a valuable lesson. When lifting the assembled crossarm and mast section into place we used a second crane to help lift the lower end of the mast to prevent it being dragged on the ground as it was lifted. It’s important to ensure the steel that forms the slip joint retains its shape as  there’s a risk it could be dragged on the ground and either get bent or damage any surface finish applied to the pylon as it’s lifted up in to place.

We’re keen to get the onsite requirements down to one crane, for both cost and sustainability reasons, and so we’re actively considering if the lower end of the mast section could be placed on a hinged platform. This would allow us to lift it with one crane and then take the platform away once it’s above the ground and ready to be fixed into place.

It’s only by having put up a life-size prototype that we can make these discoveries, so the day spent putting up the first suspension T-pylon was a great experience in helping us prepare for the future development of the UK Test Line.

In the coming weeks we’ll be putting the suspension pylon and its diamonds through mechanical tests to verify its design strength. We will use static load tests to simulate climatic (ice and wind) and security loads, dynamic tests (to understand the natural frequency of the structure) and damping tests (to ensure we have a viable solution should we need one in certain installations).

Once we’ve run through these tests we’ll erect a tension pylon alongside to see what the two look like together and then begin the next stage of tests on the tension pylon tubular diamond.

As ever, we’ll be reporting back on progress on this blog, so T-talk readers will be the first to be updated on progress.

Comments

  1. Ian Bottomer /

    Its great to see this work progressing so well and i was also interested by the article in the IET magazine (Volume 8 Issue 2 March 2013) about the pylon work being carried out by the University of Manchester in conjunction with SHETL and National Grid. The project is a trial of replacing steel cross arms with retrofitted composite insulator cross arms that reduces the overall weight of the pylon allowing more or larger cross sectional area conductors to be strung thus increasing capacity without the costs of replacing the whole tower and the issues that brings with grantors and outage constraints. Its good to see us pushing the boundaries from the accepted norm.

    Reply
  2. John /

    I love the shape, but what is the steel tonnage comparison compared to the traditional pylon? Surely this thing is going to be worse in bending due to lateral load, probably quite significantly, regardless of any ‘optimisation’ applied.

    Reply
    • Peter Botsoe /

      Hi there John,

      Thanks for the note. You are right that the T-pylon monopole structure is likely to be heavier than the lattice pylon when designed to the same specification e.g. 360m between structures, 250m above sea level etc. These design conditions enable a generic pylon to be developed for deployment in most parts of England and Wales.

      The primary reason for the difference in weight is the solid nature of the monopole and the fact that it only has “one-leg” when compared to the translucent “four-legged” lattice. Both structures are designed to cater for a number of loading conditions from extreme wind to heavy ice and security loads where wires may have broken. For the monopole, the extreme wind load condition results in the highest loads which subject the monopole to large bending and overturning moments which are withstood by increasing the steel thickness/weight.

      As indicated above, the only way the monopole with less than 10 parts can be designed to be lighter than the lattice is to make the design bespoke to the route conditions rather than to the generic specification. Along with this, reducing the distance between the structures will also reduce the structural loading.

      Taking note of the above points, the weight in tonnes of the current structures, above ground excluding bolts and nuts, for the L13 lattice, the equivalent of the T-pylon are:

      Tension (30 degrees) pylon tonnage: L13 ~59; T-pylon ~63
      Suspension pylon tonnage: L13 ~ 30; T-pylon ~41

      Trust this helps

      Reply
    • Peter Botsoe /

      Hi Liz, thanks for your note. You are correct.

      The structure we installed is uncoated and is essentially rusting…As we note in the article, it could be considered to reflect a surface finish option avialable to us which is based on weathering steel…like the Angel of the North…which rusts. The advantages of which are that you don’t have to re-coat with paints in the future say, with access every 15-25years onto grantor land i.e. a sustainable solution with potentially lower environmental impact. Obviously, the aesthetics of the pylon still need to be realised recognising that we are seeking to blend the structure into the landscape.

      We are aiming to write an article on surface finishes in the coming weeks to describe the complexities in this area…let alone the 80year coating life we are seeking – if we paint the pylon.

      Thanks

      Reply
  3. Kriss Bell-Wadge /

    I think the T-Shape pylon looks amazing. Its VERY Tall isn’t it? will it be used to replace the larger model pylons or the smaller units? Sorry if u think i am being cheeky for asking. Will the T-Shape pylon have insulators that will hold 1, 2 or 3 sets of wires each?

    Reply
    • Peter Botsoe /

      Hi Kriss,

      Thanks for your note. The 400kV (“larger model”) standard height T-pylon is at 35m roughly two-thirds the height of its equivalent L13 lattice structure which stands at just under 50m tall and in comparisson, a L7 132kV (“smaller units”) lattice pylon is roughly 27m tall.

      Our T-pylon development and deployment plans currently focus on the construction of new transmission infrastructure to connect low carbon generation based on feedback we obtain from consultation. We are not considering replacing the “larger models” as there are at least 22,000 of them in England & Wales…logistics, security of power supplies, cost etc.

      The T-pylon has been designed to hold 3 sets of wires or a triple bundle of Araucaria conductors (3x700mm sq) which represents the highest rated and heaviest set of wires we have. The power carrying capability of these wires (at 90 celsius) currently exceeds the rating of our current design of substations i.e. the design is future proof. If we need to carry less power on a T-pylon line, we could install 2 sets of wires (i.e. a twin bundle). 1 wire designs are typically used at 132kV.

      Trust this helps

      Reply
  4. john davies /

    The existing lattice designs look bad when they cross a hilltop or on open fenland, but tend to blend in most other countryside as you view through, but the ‘T’ with it’s solid monopole is unlightly to blend in anywhere except urban areas. The ‘weathered’ look will make them more obtrusive.

    How about these-

    http://www.industrytap.com/giants-carrying-icelands-electricity/824?utm_source=EngNet&utm_campaign=c4464e1ddc-EngNet_Engineering_Network_01_29_2013&utm_medium=email

    Reply
    • Peter Botsoe /

      Hi there,

      Thanks for the link. The shaped lattice pylons look great at 150ft (~45m) tall. As I’m sure you are aware, the T-pylon won an international competition (http://www.ribapylondesign.com/home) judged by an expert panel which included designers and architects. One of the judges, William Taylor, Assessor for the Royal Institute of British Architects posted an article on the competition (http://www.nationalgridt-talk.com/?p=261).

      One of the difficulties we have in developing infrastructure is assessing its impact on the environment and other effects. From a visual amenity perspective, we seek to route our lines sensitively but note that the T-pylon, a solid monopole structure, may not be suitable for some landscapes but blend well into others depending on the surface finish applied. Weathering steel is one of a number of options we are considering. Input from consultations we hold will help guide our development proposals and inform our planning application assessed by the government.

      Thanks

      Reply
      • john davies /

        Just because they’ve won an international competition judged by an ‘expert panel’ which included designers and architects won’t make them popular, perhaps before you roll them out you should put some up in a few areas so people can vote on their preference.

        That may reduce protests & save you a whole pile of grief at planning.

        Reply
        • Peter Botsoe /

          Hi John,

          Thanks for your comment. We are concious that we need the support of statutory/non-statutory bodies and the public to take forward any of our major infrastructure development projects that is why we spend time consulting in areas that might be affected.

          Part of the consultation process includes discussing the technology options that we have in mind to take on board any comments/views we may have not considered. I appreciate that showing 3D images e.g. photomontages only goes part of the way to helping people appreciate the potential impact of a development. As noted in one of my earlier posts in response to Gerry Scott yesterday, we are seeking to develop a short line in the UK later this year which people can view to help appreciate the impact of the structure, although not in the same surroundings.

          We recognise that the T-pylon as a solid monopole structure will not sit well with some people who prefer the familiar lattice but others may prefer the height reduction, narrower footprint and the ability to apply a surface finish that enables it to blend better into the landscape. Ultimately, we are legally obliged to develop these connections to new low carbon generation and we try and to do this recognising the impact on amenity as part of our planning submission.

          Trust this helps

          Reply
  5. david weaver /

    As an Ignoramus, can I ask a silly question ?

    Looking at the picture sequence showing the new pylon being assembled, it is obvious a large number of big nuts and bolts are used. As stated in the text, these have to be torqued up using access holes in the structure – one at the top centre and one in each of the ‘horns’.

    It would appear, to me anyway, that thees access holes can let the rain into the structure ‘innards’, where it can collect and rust the whole from within.

    What provision is made to counteract this ? I would assume the base of the structure – the concrete part with inset bolts – may have drainage channels ‘set’ into it, but what about the horns ?

    (maybe you have large nylon grommets you can use … )

    Thanks.

    Reply
    • Peter Botsoe /

      Hi Dave,

      you’re right that the access holes will let in the weather. As part of the ongoing design, we are still reviewing the best way to seal these access holes to ensure that corrosion due to moisture ingress does not affect the integrity of the connections. We are reviewing bolted lightweight lids or an equivalent heavy cast iron lid. The nuts & bolts will be made of galvanised steel also and so have an element of corrosion protection. Rubber bolt/nut covers will also give us further protection.

      The other issue we have to address with these construction access holes is their potential for harbouring birds/vermin etc as well as “wind whistling”…all significant issues that require us to close these holes. As part of the design optimisation, we are trying to determine how to design the holes out and still be able to construct the structure safely and in an efficient fashion. This in itself raises confined space working issues as well as directing the contractor to a specific construction methodology which may have a highe environmental impact and may not be cost/time effective.

      At the base of the structure where we bolt the monopole to the monopile via a steel flange, we will be seeking to use methods similiar to those described above.

      Trust this helps

      Reply
  6. Rob Everitt /

    Hi Peter,
    An interesting article, thanks for the update. One thing that cought my eye is that the connections are made from cast iron rather than steel, is there a reason for this?

    Rob

    Reply
    • Peter Botsoe /

      Hi Rob,

      In trying to maintain the smooth lines of the T-pylon shape at the connection points, we noted that conventional techniques such as welding would not provide an aesthetic solution even though it could be strong enough to withstand the mechanical loads.

      Bystrup being architects and mechanical engineers had experience with cast solutions in both steel and iron. Both metals can provide the requisite strength, performance (ductility, elongation etc. as defined in the design codes) and aesthetic characteristics we desired but, the costs are quite different. Cast steel and the need to heat treat mean that it is much more costly. (Note: on the tension pylon, we do use small cast steel members to fabricate the tubular diamond as we need to weld tubes to the steel members…subject to another article in the coming weeks.)

      As described in some of my other posts, we are trying to balance the project deliverables whilst ensuring we develop a cost effective solution that can be globaly produced increasing competition and hence better economy to any new transmission circuits developed.

      Trust this helps.

      Reply
  7. Gerald /

    Very disappointed to see that this business is going to overseas companies. Are there plans to manufacture in the UK in future?

    Seems a bit mad that the UK government spends £millions trying to encourage UK business and manufacturers (e.g. via the Technology Strategy Board) and yet work like this goes abroad.

    Reply
    • Peter Botsoe /

      Hi there Gerry,

      Thanks for your note. The T-pylon was designed by Bystrup (Denmark) and we are working with them to help produce the pylon.

      The timescales which we are working to are extremely tight as we are trying to develop the pylon to support major projects that are currently consulting on the development of new transmission infrastructure this year/next year… As I note in my article, for the prototype structures we engaged DS SM (Danish rolled steel; http://www.ds-sm.dk) following a market survey which had limited responses due to the nature of the project…DS SM have prior experience in power pylons (Danish TSO Energinets Eagle Pylon) and have demonstrated their capabilities by working proactively with us to construct the suspension pylon within 4months of formally engaging them. (They’re currently working up the tension pylon.) For the cast elements, we surveyed the UK & European markets and again the responses we obtained led us to select Heger Guss (German cast iron supplier; http://www.hegerguss.com/) to meet our cost & delivery requirements.

      We are currently working with UK & European suppliers to develop a short line later this year to learn how to construct, wire, maintain, register/test new equipment and ultimately train lines persons in the future. If the development activities progress well and the suppliers provide competitive quotes we’ll select the most appropriate parties to work with us…I’ll keep you posted.

      Ultimately once we have developed a tried & tested design specifications for elements of the T-pylon and one of the major projects we are obliged by procurement rules (http://www.ojeu.eu) to offer the T-pylon works scope globally to obtain efficiencies and target our key selection criteria such as sustainability which will serve the UK householder well.

      Reply
  8. Amanda /

    I think the new T shape looks great. I would much rather see these in the fields near my home. i assume with the shape that you won’t have to have fencing around the base as people would be unable to climb the structure.

    Reply
    • Peter Botsoe /

      Hi Amanda,

      Thanks for your post. The T-pylon is designed to be a non-climbable structure. As part of our health and safety obligations, we will assess if we need to implement any further measures to prevent the public from being affected by the structure…we are not obliged to cater for thrill seekers.

      With the above in mind, our current thinking is that we will generally not require any fencing at the base of the structure. We’ll keeep this under review.

      Thanks

      Reply
  9. Ash Arman /

    Can I ask is the ultimate goal to replace our existing pylons with these, or is the new design only intended for future new lines?

    Reply
    • Peter Botsoe /

      Hi Ash,

      Thanks for your post. Our work on the T-pylon is geared towards developing them as an option for delivering new transmission circuits that will connect new low carbon generation. We have circa 22,000 existing lattice high voltage (275 000/400 000 V) pylons on the transmission system and they still work well…we do not intend to replace them.

      Thanks

      Reply
  10. Martin Davies /

    Great to see the project moving forwards with the first structure being installed .
    Keep up the good work.

    Reply
  11. shingayi nyandoro /

    Consider painting the T-pylon the same colour as most army uniforms ie camouflage.

    It will then blend well with with the vegetation (camouflage)

    Reply
  12. Scott Evans /

    Good to see the “T” pylon moving forward, regarding “the hundred or so nuts and bolts which ………need to be fastened to a specific torque which can only be achieved in a tight space with a torque converter.”
    I do recall a piece of equipment that may be worth considering
    http://www.enerpac.com/en/industrial-tools/mechanical-hydraulic-bolting-tools/controlled-tightening-tools
    The, HXD-Series in particular,
    These are suitable for application where room is limited, and changes the process from physical to mechanical. We found this equipment to be invaluable

    Reply
    • Peter Botsoe /

      Hi there Scott,

      Thanks for the link. We’ll review whether the tools on offer meet our requirement and we’ll be in touch to discuss your experience of their use further. Thanks

      Reply
  13. Peter Amos /

    So the new design is more expensive, heavier and more difficult to maintain that the lattice designs, of which we have 22000? And we’ll need new bespoke maintenance equipment and linesman training, all alongside continued training and maintenance programmes for the exisiting lattice variety, so further costs all round and a move away from standardisation. All for a subjective visual improvement?

    Will the ones built in the UK be the the last ones ever built? That’s my prediction. Can anyone convince me otherwise?

    Reply
    • Peter Botsoe /

      Hi Peter,

      Thanks for the post. We expect the T-pylon as an initial concept design to cost the same or slightly more than the lattice pylon as it contains more steel and is a novel design. In the fullness of time when we can globally tender for the fabrication, optimised our construction and maintenance techniques, it is conceivable that the costs could match the lattice pylon. Regarding maintenance, the development activity is based around the use of existing assets e.g. trolleys, yoke plates, running blocks etc… Linesperson training is a fundamental need for staff working for us & with us to support the deployment of a line with T-pylons…even with our 22,000 lattice pylons we are still training resources to learn how to work on them…training never ceases where workforce change/turnover occurs and new ways of working are introduced…can’t be escaped…

      So, if the T-pylon is accepted in public consultation, our current development activities will help feed into a global procurement strategy that will seek to drive costs down and we’ll need to train linespersons to work on the T-pylon like we currently do on the lattice.

      The T-pylon may have won the 2011 RIBA, DECC and National Grid competition because of its design simiplicity, aesthetics, shorter height…but we recognise that this is subjective hence our efforts to consult widely with a number of bodies/public to help inform our planning application for major infrastructure development projects to support our line routeing efforts. Even without the T-pylon in our techology option solutions for new transmission circuits, we would still consult on the deployment of lattice pylons that we are familiar with and have been in use for many years (e.g. L8, L12…and new L13) on our transmission system because of the planning laws (“Planning Act 2008″).

      The short line that we construct in the UK is probably not going to be the last constructed as we have undertaken polls via this Blog and with Ipsos Mori on the publics view of the T versus the lattice pylons. In the main, people were more accepting of the T-pylon due to its percieved lower visual impact due to shorter height, modern 21st century design… So, I think that we may have a T-pylon line in the future but, I may be biased due to my direct involvement in the project…we’ve a number of major projects going forward and we hope they’ll reinforce my view that in +3years we’ll have a T-pylon line in the UK which demonstrates National Grid’s innovativeness and engineering capability to bring a concept to life very quickly.

      There are a number of other benefits to the T-pylon which we try and communicate in consultations which could help address public conerns…I’ll drop you a note and we can have a chat.

      Thanks

      Reply
      • Simon /

        Hi Peter,

        Very interesting and Innovative, I would like to discuss with you, your maintenance program and your working at height solution for this project and any future projects, our company can offer you a cost effective and a innovative solution. I hope this is off interest to discuss in more detail.

        Thanks

        Reply
  14. Peter Amos /

    What is the larger cost for pylons, the manufacture and erection/stringing cost or the lifetime maintenance cost?

    I quite like the new design, but suspect that for much of the public an aesthetically pleasing pylon is simply one that does not exist within view of their house. I wonder how much the height reduction over lattice design will reduce the catchment area for visual objections?

    Reply
    • Peter Botsoe /

      Hi there Peter,

      Thanks for the post. We are still in the process of investigating the representative cost of the pylons. As you appreciate, taking a prototype cost to use as a baseline for investment projections would skew results negatively. We have a good idea what the prototype fabrication costs could be but again, these in the long run would be subject to a competitive global procurement exercise potentially driving costs down. Also, we are still in the process of developing maintenance techniques which we will optimise once we have a short line of T-pylons to practice on. W.r.t. maintenance, we envisage that the use of MEWPs (…cherry pickers) will reduce the resource requirement and time to undertake activities. So, I can’t answer your question yet…when we know, we’ll comeback to you.

      W.r.t. the cumulative amenity impact of the T-pylon, we are investigating this recognising the sensitivity of this issue to parties directly/indirectly affected by their presence. In the main, we recognise that the lower height pylon has benefits. The ability to apply a surface finish that blends it into the landscape is also a significant bonus e.g. weathering steel by a line of trees. We recognise that there will be areas where the T-pylon works better than the lattice and vice versa but generally, the further the vantage point from the subject, the lower the impact.

      Trust this helps

      Reply
  15. Chris Smith /

    Certainly looks like an interesting alternative; will be watching to see the public feedback if and when these are offered on one of the MID schemes during the consultation periods.

    Have you got some comparisons in terms of the approximate volumes of concrete for the foundations (comparing a 400kV monopole suspension tower to an equivalent L13 Lattice suspension tower in like for like ground conditions)?

    Cheers.

    Reply
    • Peter Botsoe /

      Hi Chris,

      thanks for the question and apologies for the delay in responding to it…

      The T-pylon will be offered for all the Major Infrastructure Development Projects seeking to construct new transmission circuits. Some projects (e.g. Hinkley) are already presenting the T-pylon alongside a lattice solution on an equal basis to Community Forums, Thematic Groups to determine the level of interest from the public for deployment. The feedback will help us determine how we route the line and technology options to deploy.

      On your question of foundations, as I am sure you are aware the construction of new structures needs to be sustainable and make use of solutions that promote the use of recycled materials as far as is practicable. This is the strategy we are seeking to employ in all aspects of the T-pylon development. The preferred foundation solution is an innovation to National Grid, a monopile…essentially a hollow steel tube driven into the ground with a percussion hammer. (The monopile is then flanged and the monopole bolted on to it.) From a sustainability perspective, this solution does not need concrete and, modern steel sourcing techniques mean that our monopile could be constructed from between 15-98% of recycled steel.

      The driven monopile is effectively supported by ground pressure. We have sought to standardise the diameter and thickness of the monopile to the pylon base diameter and adjust the tube length to obtain the requisite mechanical strength to withstand the lateral loads on the monopole which significantly exceed the vertical loads. The monopile foundation length which is determined by calculation, can be between 9-20m depending on ground conditions and installation equipment capability. Where ground conditions do not permit a monopile of sufficient length to be driven because it is too tough (e.g. rock) or transport access is difficult, we would revert to an optimised concrete based solution. This solution would seek to use pre-cast concrete mini-piles driven into the ground at an angle tied together with a pile cap. The ultimate solution where mini-piles cannot be driven would be a raft or gravity foundation.

      A lattice traditionally sits on 4 shallow steel reinforced concrete foundations (pad or pyramid) that vary in size depending on pylon type. With a lattice, the vertical loads are dominant in design leading to 2 of the foundations being either in compression or uplift whereas a T-pylon will typically sit on a singular monopile. When comparing the standard foundation types for both pylons in similar ground conditions, the T-pylon with a driven monopile does not require concrete. Where we deploy an optimised T-pylon foundation, it is not a straight forward comparisson as we expect to use both poured & pre-cast concrete. From a construction impact perspective, we expect to use less poured concrete in the pile cap but require some additional vehicle movements to deliver the pre-cast mini-pile elements. (The raft foundation could use 8-10 times more reinforced concrete…)

      Trust this helps…we hope to publish an article on foundation design considerations in the coming weeks which will further discuss the issues above.

      Thanks (Response by Frederick Levy/Peter Botsoe)

      Reply
  16. Kristien Bell-Wadge /

    Thank you for the information. Will the ‘Tripple T’ and ‘Double T’ design become a reality or are you just working on the T-Design singular T Version? Also i was wondering if these ‘T Design’ Pylons will have lightning conductors on as if lightning strikes one it may prove disasterous as that many tons of metal crashing will have an effect on the whole T-Pylon Router system? Another question if i may? Will there be an extra high T-Shape Pylon for river crossings or has this company designed a special unit for river crossings? As a massive, massive, massive pylon fan myself i am always interested in new designs of pylon. I also would like to ask finally something about the wood pole electricity transmission lines. Would they be classed generally speaking as pylons and is there a special designated name for them as i see these wood electrcity poles all over. Some with standard insulators but some higher powered units have massed insulation units with double pole tower. I notice on the higher powered wood pole units that most of the terminal towers are twin poles 1 on 1 side and the other on the other side. I have also seen twin pole towers with 6 sets of wires near the Eggborough, Drax and Ferrybridge power stations. Are these early designs of pylon and also i love the ‘Cats head pylons’ that i seen at Tuxford, Notttinghamshire and i am sure they could be adapted for multi line use? i think probably out of all the latice steel pylon designs the ‘Cats head’ models are probably amongst my favourites along with a D-90 sharp turn pylon at Keadby Power station (my favourite place to go for a look at hundreds of pylons, i have to say!) and i always like unusual units such as three way link pylons (such as the one at Stallingborough near Grimsby, North East Lincolnshire. I’ve been very interested in pylons since i was 1 years old in 1973 and now i am nearly 41 and still have a real interest in them. Yeah i guess i am a bit of a ‘Geeky Trekkie-type’ but hey, whats wrong with that? its not harming anyone and its fun to talk about pylons to people who have the same interest, as for a long time i thought i was the only one that was really into them

    Reply
  17. Enrique Morales /

    The aesthetics of this design are excellent. Although lightning will not take this structure down, lightning effects have not been mentioned at all in any of the discussions. There seems to not be any accomodation for a shield wire in this design. Isokeraunic maps show the likelihood of lighting in the UK to not be negligible. Without a shield wire, the line is left unprotected and would take every strike not just the ones below the withstand level of the installed equipment. Equipment along the line and at the substations could be damaged. I wonder if this has been considered in the design and is just not apparent in the photos.

    Reply
    • Peter Botsoe /

      Hi Enrique,

      Thanks for the post. Part of the RIBA/DECC/National Grid international pylon competition was to ensure that certain fundamental technical/practical elements were captured. One of these elements was the need to cater for the electrical design of the pylon so that when connected into the trasnmission circuit, it did not affect the electrical performance of the network. (Please review an earlier post in October on the electrical design of the T-pylon for further background, http://www.nationalgridt-talk.com/?p=242.)

      The T-pylon has two earthwires (due to the width of the structure) that provide shielding at circa 35 degrees against lightning strikes. Lightning will tend to strike the earthwire protecting the main conductors but it can also strike the conductors themselves. The design of the diamond has taken account of fundamental electrical theory as there is no equivalent to the diamond (a unit holding all 4 wires in one system). We are this month undertaking electrical tests in Sweden at STRI (http://www.stri.se), a high voltage test laboratory capable of energising all three phases simultanously. These development tests, undertaken to IEC criteria, will enable us to asses the performance of the diamond to impulses caused by lightning/switching and also electrical stress (corona and RIV). We will then determine what design changes are required to enhance the diamond’s performance. Pollution and other long term tests are in the process of being defined for the diamond to give us even more confidence in its viability.

      All the work being undertaken is also being supported by detailed modelling of electrical transients (EMTP) to determine their magnitude and the type of economic & reliable mitigating measures that could be applied.

      We’ll try and write an article in the forthcoming weeks about the electrical design & testing work that we have completed to date. Thanks for your question and interest.

      Trust this helps

      Reply
  18. Tony Owen /

    I like the overall look of the new T Pylon, some help can be sought from the wind turbine industry, for example the simple answer to asembly of the top arms etc is to pre install threaded studs either at the factory or before lifting on the day. The same method is used to install the main rotors of a turbine. With a carefully rigged lift the sections just slip together with the studs centralising the componants, tighten the nuts onto the studs, torque up as required.
    The lack of need for internall access removes the need for access hatches, sealing solutions and the worries about wind noise.

    With regard to the exterior coatings, discount ‘weathered steel’ what that really means is we havent had time/inclination to coat it and every day that passes its corroding and getting weaker, means it needs more complex inspection and wont last half as long as the ’80 year’ coatings mentioned. If it is coated properly you can safely do a visual inspection, if its not corroded its very likely to be as strong as the day it was installed.
    Please also discount camoflage or greens/blues as there is a major duty to make these structures visible to aircraft! If you’ve flown or flown in light aircraft/helicopters etc you’ll already know how hard it is to see power lines.

    I hope my comments help with the design

    Reply
    • Peter Botsoe /

      Hi Tony,

      thanks for the note. The design of the pylon is such that the nuts & bolts are installed internal to the structure and not external to both give the bolts additional protection from the environment and improve the aesthetic design. Retaining the bolts internally means that access is required to torque the elements up although this could be avoided if the structure is completely erected horizontally (i.e. no ladders) with one “big” lift undertaken as offered by a potential supplier. We are reviewing the design and recognise that having a “door” on the structure means we can future proof the pylon e.g. to support fibre optic connections or house other services.

      On the surface coating, in discussions we are having the general perception is that weathered steel is not an appropriate coating from a visual perspective. What we are trying to do on this project is explain the benefits of weathered steel…commonly used on safety critical structures like bridges…yest they corode over time but, the design caters for this by having a sacrificial layer a couple of milimeters thick which corrodes to form a protective layer. The structure itself remains virtually as strong (tensile/yield strengths) as the day it was installed…Corrosion rates are dependent on the installation location and with the improvement in air quality, reduction in acid rain…corossion rates have sharply reduced…having a 2mm over size on weathered steel structure could easily provide the requisite 80year lifespan we are seeking with next to no maintenance. There is a limitation to siting weathering structures…not by the coastline where salt pollution will accelerate the corrosion rates. So to summarise, weathering steel does not require any coatings and hence avoids maintenance in the for of re-painting, grantor land access and potential crop damage…the weathered structure if sited in the landscape correctly e.g. by a wooded tree line provides the opportunity for an environmentally sound and sustainable solution.

      W.r.t. painted solutions, we are investigating these also as we recognise that weathering steel may not be appropriate for all locations…the paint systems we are investigating with (Hempel Denmark & UK and EA Technology) are typically epoxy based. A multi-layer solution is being sought to again avoid the re-painting operation caused by the degradation of the paint system due to ultraviolet light exposure. We are seeking to have our multi-layered paint samples accelerated age tested to determine how effective they will be.

      Camouflaged coatings are used widely across the continent on lattice pylons…we are considering these again. You raise an interesting point w.r.t. visibility for aircraft, at circa 35m tall, the T-pylon is at least one-third shorter thant its lattice equivalent and from our understanding of visual impact, the closer you approach the solid bodied T-pylon, the more visible it will becomes. Our design has catered for “countdown markers” machined into the heart (central node interconnecting the crossarms) and filled with red paint to warn helicopters & other aircraft of proximity to large structures e.g. river crossing pylons; substations etc.

      Trust this helps

      Reply
    • Peter Botsoe /

      Thanks Emmanuel,

      interesting looking pylon. If we get the chance we’ll try and investigate it further to understand its design principles. Thanks for bringing it to our attention.

      Reply
  19. Jim Burton /

    It might be possible to save weight and gain strength by having internal struts and braces similar to bird bones that are specially formed for lightness without losing its integrity as a structure.

    Reply
    • Peter Botsoe /

      Hi Jim,

      thanks for the note. You raise an interesting point. With the suspension pylon, due to time pressures we’ve constructed a structure much heavier than we wanted to due to the use of readily available steel plates. Our thoughts on reducing the weight of the structure including using higher grade steels (S420 instead of S355) and irons (GJS500 instead of GJS400) or different fabrication processess (hot rolled steel instead of cold rolled…greater strength with less steel)…we also have other thoughts…

      With all the options noted we are seeking to balance sustainable design, simple fabrication & field construction techniques with economics. A tall order but one we are working hard to achieve.

      Thanks for the post.

      Reply
  20. Dale Milligan /

    The picture shows part of the T-pylon rusting. The best metal to use is stainless steel because it is strong and will not rust.

    Reply
  21. Dale Milligan /

    I don’t like the design of the T-pylon. I think the pylon design currently used in 2015 looks better than the T-pylon. I think the T-pylon looks horrible. The current pylons should have a structure made of stainless steel. Stainless steel does not rust.

    Reply

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