Pulling Conductor - Transmission Line

In summary, the individual is seeking information on whether their pulling equipment, with a safe working load of 4000 lbs, can handle a 795 drake conductor double bundled (times 2) across 16 spans with an average span of 674 feet and towers that are 115' tall. They are also curious about the tension variations with temperature and the number of spans. They receive advice to consult the ground-crew foreman and EPRI for calculations and recommendations.
  • #1
Jarmstro
2
0
I need to figure out if my companies pulling equipment can handle a 795 drake conductor (about 1 lb/ft) double bundled (times 2). The pulling equipment has a safe working load of 4000 lbs.

We are pulling it across 16 spans with a average span of 674 feet. the towers are 115' tall. Max sag tension is 4441lbs. If we pull at 50% sag tension, will the equipment be able to safely handle the load of 10,557 total feet of conductor? I understand tensions will vary with temperature, I just need an approximation.

How does the tension on the pulling equipment vary as the total length of wire is pulled and also how does tension vary with the number of spans this pull has (more tension for only 1 span as opposed to 16 spans?)

It has been a long time since I have done load calculations. Can anyone refresh my memory?
 

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  • #2
Go ask the ground-crew foreman. I'll bet he has done it often enough to have intuition and conservative rules of thumb, otherwise he would have been fired for breaking things.
 
  • #3
Pulling in both wires at same time is over 4000 pounds assuming your sag tension is 4000 pounds per individual conductor, or 8000 pounds for the bundle. 50 % pulling ten would be 4000 pounds round numbers, plus energy losses over the rollers, plus any line angles in the pull would create additional problems.
 
  • #4
Thanks guys! This helped!
 
  • #5
If you must do this by calculation, give some really serious consideration to the friction developed at each tower. The longer this thing gets, the more friction there will be and this is likely to be your undoing.
 
  • #6
Contact EPRI (electric power research institute). I would not be surprised if they don't have a software program for those calculations that you could use. The utility you contract with is likely an EPRI member.
 

1. What is a pulling conductor in a transmission line?

A pulling conductor, also known as a messenger wire, is a flexible wire or cable that is used to pull transmission lines, such as electrical wires or fiber optic cables, through a conduit or over long distances.

2. Why is a pulling conductor necessary for transmission line installation?

A pulling conductor is necessary because it provides a strong and flexible support for the transmission line during installation. It also reduces the tension and stress on the transmission line, preventing damage or breakage.

3. What are the common materials used for pulling conductors?

The most common materials used for pulling conductors are steel, aluminum, and composite materials. Steel is strong and durable, while aluminum is lightweight and easy to handle. Composite materials, such as fiberglass, are also lightweight and have a high strength-to-weight ratio.

4. What factors should be considered when selecting a pulling conductor?

When selecting a pulling conductor, factors such as the length of the transmission line, the weight of the transmission line, and the type of conduit or terrain it will pass through should be considered. The material and strength of the pulling conductor should also be evaluated based on the specific needs of the project.

5. Can a pulling conductor be reused?

In most cases, a pulling conductor can be reused for multiple installations. However, it is important to inspect the pulling conductor for any signs of damage or wear before each use to ensure its strength and integrity. If any damage is found, the pulling conductor should be replaced to prevent potential accidents or failure during installation.

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