Twisted pair overhead power lines? Why?

[Dean Hoffman]

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?

[trader_4]

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.

[philo]

Enough info here to get your answer

[Dean Hoffman]

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.

[Tony Hwang]

IMO. that is to improve power factor. Just a hint.

[hubops]

Overhead distribution and transmission conductors would usually be ASCR aluminum-conductor-steel-reinforced. :

Vibration dampers are installed near the tower :

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

--- news://freenews.netfront.net/ - complaints: [e-mail] ---

[clare]

It's not "twisted pair" - it's "triplex" and yes it is stronger than individual wires, and they can't whip and hit each other either. The neutral "carier" is usually a twisted steel cable and if not steel is high strength aluminum alloy

[dpb]

It _IS_ twisted pair, not triplex. These are transmission lines, not service entrance.

See the links philo posted altho here's the link to Southwire's product page--

Not sure who's Dean's REC is; here's one near us (altho not us specifically, they're just west). We started a number of years ago after a massive ice event took almost 60% of our total transmission lines down.

[Dean Hoffman]

Some cut.

My curiosity got the best of me so I went to snoop. Each span had about five of these things curled around each of the individual cables. They are white. Imagine an extended spring wrapped around the line. I couldn't tell for sure if the cables were twisted pair or single line.

[Dean Hoffman]

I'm about 60 miles north of the Kansas border. The worst storm for power outage was in the spring of 1976. There's a bit here

if anyone is interested. Pictures of helicopters hauling assembled structures included.

[clare]

Yes, I was thinkingservice entrance

The Vr2 "compound" cables are wind and vibration resistant - and when it moves it dislodges ice a lot faster than round cable.

[dpb]

On 02/07/2016 3:28 PM, [e-mail] wrote: ...

Not really...the gain is in the resistance to wind- and ice-"galloping" that is the real stress-producer, not just the dead weight of the ice.

I don't know there's any study/data on actual ice-shedding, per se. It's never been a topic from our REC engineers in choosing one product vis a vis another for the purpose (and believe me, we've had a lot of discussion and engineering input on the subject).

[dpb]

On 02/07/2016 3:18 PM, Dean Hoffman wrote: ...

So you got hammered a week ago??? How far from Goodland, on north or farther east/west? They're straight north of us 180 mi or so...

I forget which year it was our ice was so bad, but per typical SW KS it also came w/ 50+ mph sustained wind, gusts to 70-80 mph estimated...

[dpb]

On 02/07/2016 4:51 PM, dpb wrote: ...

Oh, but it was since 2000 'cuz we came back to the farm in '99-'00 time frame after Dad died...

[Dean Hoffman]

I'm north of Salina give or take. Grand Island got hit the worst last week with about eighteen inches of snow. We got about a foot. The kids here got a couple days off from school. The local officials had enough faith in the forecasts to announce the shutdowns ahead of time. That storm back in '76 prompted the telephone companies to bury their phone lines. A co worker from back then had a field day. Some of the insulators were worth money.

[clare]

Any flexing causes motion between the conductors whch cracks the ice loose

[Dean Hoffman]

Yeah, one question answered. I tried to find a picture of the rods wrapped around the conductors but wasn't able to. My news reader is acting weird. Your reply was a bit away from the others.

[dpb]

On 02/07/2016 5:41 PM, Dean Hoffman wrote: ...

OK, you're "way back east" then... :) Ice is much more of an issue there than typical out here...we've got a lot more wind, though, generally.

[Micky]

OT, but just wanted, without any attempt to be sarcastic or nasty, to ask when ice storm became ice event. I heard on the radio a few days ago, bleeding event, as opposed to bleeding. Is the new occupation of event planner the reason there are so many more events these days?

[DerbyDad03]

It may be related to the description of an ice storm found here:

The first paragraph states:

"They are not violent storms, but instead commonly perceived as gentle rains occurring at temperatures just below freezing."

If I look outside and see "gentle rains" I'm not going to say "Wow, what a storm!" So why I should refer to the resulting coating of ice as a "ice storm"?

Since an "event" is basically something that happens, an ice event, a snow event, a bleeding event basically means that ice happened, snow happened and bleeding happened.

What sucks is when they happen all at once. ;-)