This will help cut energy costs... Old news, but new technology still

http://technology.newscientist.com/channel/tech/dn11907-superconducting-power-line-to-shore-up-new-york-grid.html

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dorothy with the Red Shoes on wrote:

http://technology.newscientist.com/channel/tech/dn11907-superconducting-power-line-to-shore-up-new-york-grid.html
I was in New York recently. On a few road junctions near Broadway I saw roadside nitrogen cylinders with hoses leading under the road and have now started puzzling over that. Cooling something?
Then I hit google ... <http://gothamist.com/2008/01/31/nitrogen_tanks.php
Keeping telephone cables dry, and displacing arms and legs ...
--
Adrian C

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

In the UK, telephone exchanges contain units which dry and compress air, and this is pumped into the cable jackets where they leave the exchange. Many of the old very-many multi-pair cables have what looks like paper insulation, but is more accurately described as "air insulated, paper spaced" insulation. It's clearly essential this stays dry, and these cables were designed from the outset to be run with pressurised dry air passing through them.
I was in a small village exchange about 10 years ago, talking with one of the exchange engineers, and the air compressor was starting up periodically to charge up the pressure vessel. He said the management decided to switch it off at one point. Within a month, they were inundated with faulty lines, and it took 2 years of running the compressor to get back to the previous state of the lines.
I suspect such cable is not used in new installs for some time now, but there's loads of it in use in the ground.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Not just phone cables
The Forth Road Bridge is having dehumidification fitted to stop corrosion in the [corroding] support cables, nevertheless its service life could be just a few years.
OTOH The Oresund Bridge had this from the outset and should last centuries.
writes:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Adrian C wrote:

You have to wonder if those tanks give off enough nitrogen to create a suffocation hazard in the cable vaults or even leaking into subway stations.
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
says...

I've always seen active ventilation used when they're working in cable vaults. Subway stations are pretty big and I would hope there is some active ventilation there too. They'd get pretty rank otherwise.
--
Keith

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What, like big pistons (a.k.a. trains) running in tubes (tunnels)? Certainly, the London Underground is very windy. (I haven't used the New York subway for about 13 years, and I can't remember.)
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
snipped-for-privacy@cucumber.demon.co.uk says...

No, like ventilation shafts and fans. (tunnels are too long).
--
Keith

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.