Increased tension due to pole raising 1

[MSOMT]

We are looking at using phase-raiser on a transmission structure which would raise the conductor attachment points by 10'. The span is 600'. How would I determine the increase in tension in the conductor due to this change?

 

[jalexiou]

Roughly the span has become from 600 ft to 600.0833 ft. Consider this a change [Δ]S=0.0833. To calculate the change in horizontal tension, if the total cable length is unchanged use

[Δ]H/[Δ]S [≈] 12[·]H[³]/(S[³]w[²])​

where H is the horizontal tesion, w is the linear weight and S is the horizontal span.

Of course this is an aproximation, as the cable will stretch more with the increased tensions. To get an accurate result you need a proper sag & tension software.

John Alexiou
Alcoa Design Engineer
MSME Georgia Tech

 

[MikeDB]

Can't verify the above equation, but tried an example and the results did not seem to be even be in the right ball park so I may have entered something wrong.

For 5 or 10 foot changes in structure height on spans that long, I don't think most would even consider the change in tension. If you are a PLS-CADD user with the SAPS feature, there is a routine in there to do just what you are considering.

If you are not on level ground, the tension may increase or decrease, depending on the pole being raised.

 

[MSOMT]

Thanks for the help!

I have Sag10, is there a way to get an accurate answer using it?

If not, I might try sending it to one of our other offices that has PLS-CADD.