230 kV Wood Pole vs. Steel Pole 1

[cuky2000]

We are performing a assessment to use wood pole vs, steel pole for a 230 kV transmission line in a wide territory in the Northern of USA.

Any advise or recommendation to use wood pole vs. steel mono pole or lattice structure?

Thanks

 

[cranky108]

One concern is the insulators you use. The steel pole will conduct, where the wood pole will offer some impedance to conduction.

Also steel and a copper ground needs to be clamped with the right hardware to prevent galvantic action. Wood dosen't have this problem. Also the grounding of each, or every third, or whatever, should be consitered, in that a pole butt ground is possible with wood, but steel requires a driven ground.

 

[stevenal]

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[Marmite]

Where I come from it would be unheard of to build a 230kV transmission line with wood poles. Usually for transmission at the higher voltages the circuit reliability, capacity (physical and current carrying) and life span requirements wouldn't be achievable with wood structures. Does this have a very small load at the end?
Regards
Marmite

 

[jghrist]

Wood poles have a higher BIL with the same insulators because of the insulating properties of wood. Steel poles can be made stronger than wood poles, with longer spans and fewer, more expensive poles. Lattice steel towers can be made stronger than steel poles, with longer spans, but may be considered less aesthetically pleasing. Usually it is an economic decision.

 

[FreddyNurk]

Where I live in Australia they use timber poles extensively for distribution, but I've never seen a single wood pole used for any transmission applications. Surely with the height required for a 230kV application this would preclude any single timber pole, and would require a structure made of timber instead?

Spun Concrete poles are also popular as an alternative to the lattice steel towers.

 

[davidbeach]

Wood H-frame (two poles with a cross arm near the top) is a extremely common 230kV line construction in the US Pacific Northwest. We even have a few examples of single wood poles with 230kV. We grow them big here, 100-120 foot poles are not uncommon.

 

[racookpe1978]

Do you have ANY plans (even remote possibility) of expanding capacity or line weight (dia) later? A wood pole (unless H tower) is going to be limited to expansion .

 

[FreddyNurk]

I never would have expected that timber poles would be used for such applications, but there's always something new to learn. Given the weather patterns where I used to reside I'm amazed they still used wood, but not all locations are the same.

 

[cranky108]

Also in the US we sometimes use steel poles on distribution. Never understood the cost value thing there.

However, in the US, to makeup for the wood pole lower strength there are more structures per mile. But where there are taller trees, there are generally lower wind speeds.

Also pole treatment should be factored into the equasion, and pole life at the location it is installed. Same issue with steel, and footing size.

 

[crshears]

Don't forget to factor in wildlife activity...

Our utility has occasionally [in the northern part of Ontario, Canada] had major issues with wood pole damage by pileated woodpeckers - and these birds give not one whit for the nominal voltage of the equipment being supported, provided they don't get so close to the conductors as to experience corona tickle !

Wooden poles [as opposed to steel ones] provide an excellent gripping surface for birds , and often have a resonance characteristic that makes them peculiarly appealing as prime drumming objects for use in establishing and maintaining territorial boundaries - and unfortunately when a bird has decided precisely where the "sweet spot" is on a particular pole, it bangs away at it repeately...

Local topography and forest considerations, viz., tree species, their height, age, health, etc. have profound effects on whether or not ornithological damage to wood poles becomes problematic.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]