Tell us about your last flight

[facthunter]

 Easier to alter and tap into and access Transformers etc Probably less Loss. Transformers have to be cooled.  Nev

[BrendAn]

i asked a mate at western power about this years ago and he told me that underground wires can't dissipate heat sufficiently.

[skippydiesel]

1 hour ago, BrendAn said:

i asked a mate at western power about this years ago and he told me that underground wires can't dissipate heat sufficiently.

Interesting - I hadnt considered that possibility.

 

I wonder what heat is generated - I have lived in countries where ice can accumulate on power lines and in some cases cause both the lines &/or the towers to fall.

 

One would think if heat is a significant operational  issue, the ice would not have been able to "stick" & accumulate.😈

[BrendAn]

Just now, skippydiesel said:

Interesting - I hadnt considered that possibility.

 

I wonder what heat is generated - I have lived in countries where ice can accumulate on power lines and in some cases cause both the lines &/or the towers to fall.

 

One would think if heat is a significant operational  issue, the ice would not have been able to "stick" & accumulate.😈

no idea.  

[BrendAn]

Instead, some of it is lost in the form of heat. That’s because no matter how efficient of a conductor a power line is, electrons will collide with other electrons, atoms and material in the line as they move through it. These collisions cause electrical resistance and generate heat.

 

found this on the net

[skippydiesel]

I don't doubt the generation of heat - its a question of;

• How much heat?
• Could the heat be mitigated/contained, such that it would not impact on underground power?
• Could the heat be used in some way?

From distant memory & recent Google, I saw very few aerial power lines in the City Of London. I assume this is likly to be the case in most large (western?) cities. If they can do it (large power demand) why cant it be done elsewhere - or is it just about the quick return on capitol?😈

[onetrack]

Plenty of new suburbs have underground power and in the older suburbs in my neck of the woods, the councils are generally aiming to underground power in the long term. The residents have to pay for it, though. The councils offer loans to help the residents deal with the cost.

It increases the value of the housing where power lines are underground. At least with underground power you don't have powerlines coming down when some clown hits a power pole. And the removal of power poles reduces the amount of crashes.

[BrendAn]

26 minutes ago, onetrack said:

Plenty of new suburbs have underground power and in the older suburbs in my neck of the woods, the councils are generally aiming to underground power in the long term. The residents have to pay for it, though. The councils offer loans to help the residents deal with the cost.

It increases the value of the housing where power lines are underground. At least with underground power you don't have powerlines coming down when some clown hits a power pole. And the removal of power poles reduces the amount of crashes.

when i spoke to the western power bloke it was about the powerlines from collie to albany after we had a big fire at tenterden caused by a powerpole fire. a lot more voltage than subdivision.

[onetrack]

Yeah, they usually run the high tension powerlines at 132Kv, but unsurprisingly (when you think about it), the amperage is very low, they only have something like 5A fuses for the HT lines.

I wasn't aware the HT lines heated up all that much, this is the first time I've heard it mentioned. One would expect cables carrying high amperage would heat up, but not low amperage cables.

 

Edited Wednesday at 12:59 PM by onetrack

[Siso]

Windfarms have underground cables and it is a regular occurrence, mainly at the joints. It has been suspected that as sometimes the cables are running flat out and than not carrying anything at other times the heating and cooling cycles cause the cables to grow and contract and the joints the weakest point. The cables had 3 phases in them and the joints heatshrunk? together. We ended up splitting up the cables for several metres at the joints and mounted each phase a metre or so apart to a frame underground. This seemed to fix the problem as we only had one failure in the last 6 or 7 years I was there. There a transmission lines in Australia that run up to 500kV. Portland Vic heading back towards the coal fired stations. 132, 275kV are the common ones.

[skippydiesel]

From the above comments, I am starting to think that underground transmission is in fact a viable option;

• Farmers would be less likly to appose well berried cables.
• The attrition rate on Ag pilots would be reduced.
• Safer for all above ground critters, including homo sapiens
• No blight on the scenery
• No sparking of fires
• No lightening/wind/sunspot outages
• Likly reduced maintenance costs and increased service life of cables

 

Just have to get over that slow return on capital  mindset.😈

[facthunter]

Insulation is VERY critical Underground . Above ground it's achieved by the distance to an  Earth The wires are not Covered. Very high voltages reduce transmission losses and Have Less AMPS but require More distance from an earth to avoid ARCING . There can also be capacitance losses. Wires are cooled by the Air. Transformers are also ( usually through OIL.)

  Companies in the game Know the relative costs. As wires heat up they droop lower. Usually in response to AMBIENT temps and sunlight. Not load.  Above ground has Lightning Protection these days to protect against damage to  household items by Over voltage  Houses should have  Lightning protection in their Own Right.  I Installed about 180 Metres of Underground cable to my House when I built it ( Multi Phase), But I doubt it's worth the cost and trouble. Nev

[Thruster88]

Is this Tell us about your last flight or the electrical power distribution forum, 25 replies so confusing. 

Edited yesterday at 05:27 AM by Thruster88

[onetrack]

Blame pmccarthy - he was the one who showed power pylons, and a transmission line from the air!  🙂

[facthunter]

Well THAT COULD cause your LAST flight, and it's Nice to Have Power to your Hangar.Nev. 

[RFguy]

I have alerted moderator to kill off all power discussion, have marked as spam.

[facthunter]

I would regard that as the Moderators job, IF HE sees Fit. There's plenty of Instances of thread drift and worse. Making a Joke of a serious subject which Kills it dead. Nev

[Admin]

I think we need to get back on track. If you wish to discuss about power then there is other forums more specific. Thanks

[skippydiesel]

One of the great things about this Forum is what you learn - aviation, non aviation & the quality of the debate (for the most part)😈

[Ian]

On 24/09/2025 at 5:22 PM, skippydiesel said:

Would the subterranean power lines have the  (a) same (b) lower (c) higher maintenance cost ?

 

While putting the power lines underground may be "to appease local voters" , there is no doubt in my mind that it its better for the visual amenity, unlikly to suffer from wind/fire/electrical storm damage and will not injure/kill fauna or unlucky persons.

 

I suspect that the service life of underground cables is significantly longer than for aerial.

 

The upfront investment may be higher (as you suggest) however once established , the pipelines carrying the cables would have a very long service life.

 

"...............transmission lines are expensive enough that you've zero hope of getting the capital back."

 

This is one of the biggest problems of a capitalist society - the obsessive need to have a (quick) return on capitol. 

 

All too often Government makes short term decisions  - leaving the down stream costs/impacts to future governments/generations to deal with.

 

I am not convinced that underground  power reticulation, would not be cost effective in the long run.😈

 

It doesn't matter if you're not convinced. The fact remains underground HVAC is a shitty solution.

 

As stated, the main reason for underground cables is voters and very occasionally safety related issues such as proximity to a runway.

 

Would the subterranean power lines have the  (a) same (b) lower (c) higher maintenance cost ?

Generally lower maintence costs however things like active soils etc can reduce lifespan. But this is dwarfed by installation costs.

 

I suspect that the service life of underground cables is significantly longer than for aerial.
The same line again
the pipelines carrying the cables would have a very long service life.

The service life of underground power lines is less than above ground. Generally about 40 years for below ground and 60 years above ground but technologies may change this. 

The service life is lower because it's a harsher environment, water ingress, salts, ground movement etc. The other differences is that you are likely to be able to increase the capacity of above ground powerlines at a later date. This isn't an option with below ground.

If you don't believe the service life argument ask a farmer if fenceposts last longer above ground or below ground.

 

Below ground power lines are technically an inferior solution. For example most power lines are heat limited, heat dissipation is worse underground as the ground acts as an insulator. You also get higher capacitance leading to higher power losses in operation. So you lose more power per km underground than above ground.

In short underground power-lines cost many times more, don't last as long, can't be uprated, have higher power losses and are heat limited. 

If you're not convinced, do the research.

 

https://shop.elsevier.com/books/transmission-and-distribution-electrical-engineering/bayliss/978-0-08-096912-1

 

Note the safety related runway context to make it aviation related 😉

 

 

Edited yesterday at 08:20 AM by Ian

[facthunter]

We have ALL sinned and fallen short of the Glory of God. We also seem to be easily distracted and lacking of Self discipline.  It may also be an attempt to correct a perceived error rather than let it Pass and have the Opportunity lost. IN Flying you correct errors as soon as they are detected. Maybe it's a HABIT Hard to toss. Nev

[Ian]

Amen

[BrendAn]

3 hours ago, Admin said:

I think we need to get back on track. If you wish to discuss about power then there is other forums more specific. Thanks

i flew over some powerlines the other day.

[Moneybox]

4 hours ago, RFguy said:

I have alerted moderator to kill off all power discussion, have marked as spam.

Does he have the power to do that?

[planedriver]

1 hour ago, BrendAn said:

i flew over some powerlines the other day.

You're supposed to mention that Brendan, Shh! 😉