On Sun, 07 Feb 2016 10:27:32 -0600, "Dean Hoffman"
wrote:

On Sun, 07 Feb 2016 10:02:42 -0600, trader_4 wrote:

On Sunday, February 7, 2016 at 10:56:07 AM UTC-5, Dean Hoffman wrote:
The local REAs have been putting in twisted pair lines in the last
few years.
Does that help keep them from going down in ice storms?
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Twisted lines for what exactly? Around here twisted lines for
a service to a house are common. I would assume because it
keeps them together and neat. Twisted high voltage wires, that
I haven't seen.

The high voltage lines along the roads carrying power to farms.
I think those are about 7200 volts. I want to say only on three
phase but don't remember for sure. Why a twisted pair rather than
a larger single conductor?
The three phase is mostly for irrigation well motors and grain drying
fans. The well motors are mostly 480 vac. I don't know if the grain
dryers
are mainly 480 or 240v.
I've seen the transmission lines (115,000v or so) have twisted rods
wrapped
around them in about the middle of the spans. I guess that's to prevent
galloping in high winds.


Overhead distribution and transmission conductors would usually be
ASCR aluminum-conductor-steel-reinforced. :
http://www.sale-cable.com/Bare-Condu...-BS-215-2.html

Vibration dampers are installed near the tower :
https://en.wikipedia.org/wiki/Stockbridge_damper

.... not sure what you're seeing mid-span ?
I've seen phase-spacers installed for anti-gallop.
John T.



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