the distance between towers in transmission lines 5

[haithampower]

hi every one
I need to know ...how I can calculate the distance between the towers in transmission lines for 33 kv ,132 kv,400kv ..etc
thanks
haitham

 

[cranky108]

1. you could measure the distance.
2. If you know the pull of the line, as designed, and the minimum required clearance, and the ground contours, you can figure the needed pole placements.
3. Ask someone who knows.

 

[jghrist]

You could start with the Rural Utility Service RUS bulletin 1724E-200, "Design Manual for High Voltage Transmission Lines (12/2/15)" available at

https://www.rd.usda.gov/publications/regulations-guidelines/bulletins/electric

 

[waross]

As the span increases, the towers must be stronger to support the increased weight, wind loading and ice loading of the conductors.
Stronger towers cost more.
With increased spans and the same tension on the conductors, the sag will increase and so the towers must be taller.
Taller towers cost more.
The cross section of the conductors may be increased so that the tension may be increased and the sag reduced and so the towers must be stronger again.
Stronger again costs more.
There may be controlling factors on the height or the sag.
eg: Two parallel 500 kV lines several hundreds of miles long were built with a standard tower height of 79 feet. Why? Labour costs in that jurisdiction doubled for work at heights above 80 feet.
A nearby airport may influence the maximum allowable height of towers.
In the case of highway crossings, river crossings, railway crossings, and similar situations the sag may be limited by the minimum allowable ground clearance.
The design is often a compromise. You may find yourself designing and pricing several standard span lengths to find the sweet spot. Then evaluate any areas with special restrictions.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[stevenal]

See forum608.