it’s not as simple as saying “ok, I want self-supporting tangent mono poles with delta configuration for my entire 80 mile stretch.” While that idea might be more economical than having h-frame or 3-pole structures, it’s just not practical.
Ultimately, the wire configurations determine which type of structure will be used, and typically there will be a mix of these structures in order to follow the right-of-way through small or tight turns. Right-of-ways go alongside or through interstates, highways, fields, woods and even water, so an engineer must keep all these situations in mind when designing.
Three common transmission structures:
Used when transmission route is straight
Generally, no longitudinal loads on the structure
Used when transmission route changes direction
Used from anywhere less than a 5 degree angle to a 90 degree angle
As name applies, dead-ends are designed to take the full component of every wire's tension
Does not necessarily mean end of transmission line
Whether the structures are tangent, angle or dead-end, wire phases can run in multiple configurations. Horizontal Configurations provide the lowest profile. Vertical Configurations require the minimum width right-of-way. And Delta Configurations is an attempt to use the value of both horizontal and vertical configurations to maintain phase clearances.
Self-Supporting Structuresdo not use guys: meaning they are not tied to the ground or any other structure in a way that offers additional support. They are better for restrictions to right-of-ways and tend to have loads small enough to not warrant guys.
Guyingof structures is used to support the structure and allow for a more economical design in both the steel structure and foundation. Guying reduces bending and deflection. However, the downside is that it requires more right-of-way.
*Here are some main contributing factors to keep in mind when deciding on whether or not to guy a structure:
Aesthetic design criteria
**Here are some other contributing factors you may want to consider:
Electric air gap clearance requirements
Ground clearance requirequirements
Number of circuits to be supported
Electric and magnetic field limits
There is so much to learn about Transmission Structures.What questions do you have? We would love to hear from you so please leave a comment below.
Check out our newest resource for Anchored Transmission Structures. Click below.