Pulling Conductor - Transmission Line

[Jarmstro]

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?

 

[Doug Huffman]

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.

 

[PhanthomJay]

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.

 

[Jarmstro]

Thanks guys! This helped!

 

[Dr.D]

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.

 

[anorlunda]

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.