There are many different types of transmission structures used to deliver power. Clean Line Energy is evaluating the use of steel H-frame, monopole, and guyed 3-pole alternating current (AC) transmission structures for its Western Spirit transmission line. The majority of the line will use H-frame structures; monopole structures will be used near river crossings, and guyed three-pole structures may be used when the transmission line changes direction. Whether a “running angle” or “dead end” guyed 3-pole structure is used will depend on the curvature of the turn.
The images below show average specifications for typical steel H-frame, monopole and guyed 3-pole structures.