Transmission lines act as the utility interstate system where electricity is transmitted at high voltages in order to reduce the energy lost in long-distance transmission.

Although it’s hard to quantify structure types since there are always exceptions to the rules and never-ending configurations, transmission structures can be considered dead-end, strain or suspension.

A dead-end structure is where conductors and ground wires are pulled only on one side, unless it is a double dead-end structure, and are used where:

•    Line ends
•    Line turns at a large angle
•    At major crossings like highways or rivers
•    Divide line into segments

For strain structures, the conductors are directly attached through in-line insulators through or around the tower. In suspension transmission structures, the conductor phases pass through the structure, and are suspended from the insulator.

Each structure type can either be classified as tangent, with no line angle, or angle, when there is a line angle.

Tangent, angle and dead-end structure

Steel transmission structures can be designed with tapered tubular poles, which are hollow, can be multi-sided and have a large base that tapers down, typically in the range of .18 to .45” per foot.

And to dig a little deeper, all of these structures can either be guyed or unguyed. A guyed structure provides extra support by fastening a wire from the structure to the ground or another structure, whereas an unguyed structure is self-supporting.

When deciding which type of structure is most economical, as well as best suited for varying conditions, there are many considerations that can influence which to select, such as:
•    Terrain type
•    Erection techniques
•    Electrical constraints
•    Access & transport situation
•    Procurement & easements
•    Structural loading

Want to learn the three types of transmission structures? Or what to consider before guying a structure? Download your copy of Transmission Structures and Their Configurations today.


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