Electrical Transmission Towers

........Cost Effective, Easy Installation

This tower, shown under test, is an eight-guy, Y-tower used for a 500-kV transmission line by Ontario Hydro, Canada. Bulb angle chord sections are used in the body of the tower.

All-aluminum towers were first put into service in 1959 by several utilities. Prior to 1950, aluminum was used in combination with steel. Weight reductions of 50-70 percent can be realized over equivalent steel structures. Initial price differences with steel can be completely offset because of lower erection costs in the field and lower maintenance costs over time. An aluminum three-pole guyed angle tower weighs approximately one-fifth that of a self-supporting steel tower and, with a smaller base, can be installed with relative ease.

High-strength, relatively low-cost prefabricated aluminum is challenging steel today for construction of 138-kV and higher transmission towers. Not only does aluminum give designers a higher strength-to-weight ratio, it also affords better corrosion resistance than steel, multi-form shape extrudability, and reasonable prices.

Installation costs are also dramatically reduced by using aluminum. Aluminum can be extruded into shapes that maximize torsional rigidity and radii of gyration. Lightweight, conventional erecting equipment can be used to build the tower, as well as faster methods—thereby meeting fast-track construction schedules. Helicopters can also be used to lift, shift, or move components into place, irrespective of how rough or inaccessible the site may be.

In electrical transmission, interruptions of service for maintenance work are unacceptable, giving maintenance-free aluminum towers a definite advantage. Because aluminum offers outstanding corrosion resistance, painting and upkeep is unnecessary, a dangerous, expensive, and time-consuming process in steel towers. To meet non-glare requirements, surfaces of aluminum towers can be treated with coatings that need little or no maintenance.