What is really expected from a power line structure? Is it only a technical necessity, an object of design excellence or a piece of land art? The best answer probably lies somewhere in the middle of all three.
Because there are so many power line structures and because they are often situated along busy roads and highways, appearance has become almost as important as function. Towers perceived as damaging the natural landscape quickly become objects of public disapproval. In fact, that is precisely why the power supply industry is in a situation where it must overcome great obstacles to erect yet more of them.
One of the challenges facing all line planners is optimizing design to meet mechanical and electrical performance as well as cost and durability requirements. Clearly, a technically demanding item such as a power line structure needs to be far more than something that is only pleasing to look at. Moreover, since these technical challenges vary with voltage, a new design approach may be needed whenever voltage levels change. A structure designed and optimized for 220 kV may not work effectively for other voltages.
It is also important to take conductors into account since these have significant visual presence as a transmission line moves across the landscape. That makes configuration of conductors as important to consider during line design as are their support structures.
Yet another important aspect of design is choice of materials. There are now far more options available than when lattice towers were first designed a century ago and a range of alternative materials is available to help overcome the generally negative public perception to lattice structures. Using the latest generation of materials can even help optimize speed of construction and lower project cost – apart from the goal of contributing to improved appearance. Similarly, uniformity of materials used in structures can help improve visual impact by reducing unnecessary clutter.
One group of materials being closely examined these days are fibre composites whose intrinsic insulating properties open entirely new possibilities for power line structures. For example, such a structure can be designed without requiring traditional cross-arms equipped with insulator strings since the structure itself effectively acts as insulator. This allows structures that further minimize visual impact. Proper use of fibre composites can also help compress structures and minimize a line’s height, subject to meeting ground clearance and electric field requirements. Similarly, utilizing the insulators themselves as cross-arms can reduce tower height as well as number of different structural members.
It is clear that there are not only challenges but also opportunities when it comes to expanding the power grid while minimizing resistance from affected communities. But to realize these opportunities, line designers will have to go beyond their ‘comfort zone’ of relying only on tower concepts of the past. A contemporary power structure with high design component is the best way to overcome opposition to new lines and, through its appearance, remind the public that electricity is the only sustainable solution to our long-term energy needs.
Given the above considerations, some of which were part of a past INMR article contributed by industrial designers, Bystrup, in Denmark, below, in random order, is a selection of admirable power structures seen over nearly 30 years reporting on overhead lines across the globe. These are referred to as ‘admirable’ because they have succeeded not only to fulfil their basic function of transporting electrical power but also do so with high aesthetic value and/or minimal adverse visual impact on their surroundings. Some are even inspiring to look at and project a positive image for the power supply company that operates them. In a world populated by mostly monotonous and occasionally bizarre power line structures, this is worth admiring.