Recliner wrote:
Charles Ellson wrote:
On Sun, 17 Apr 2016 18:29:31 -0500, Christopher A. Lee
wrote:

On Sun, 17 Apr 2016 20:56:35 -0000 (UTC), Recliner
wrote:


What's wrong with just using 3rd rail beyond Amersham,

More expensive, obsolete, less efficient and it's heading toward 25kV
territory.

Much *cheaper*, surely? Less efficient, yes, but why should it matter that
it's headed towards 25kV territory?

The high cost of DC 3rd rail comes from the need for more complex and far
more frequent substations. You can get a lot of 25 kV line covered from a
single feed.

Robin

In article , (bob) wrote:

Recliner wrote:
Charles Ellson wrote:
On Sun, 17 Apr 2016 18:29:31 -0500, Christopher A. Lee
wrote:

On Sun, 17 Apr 2016 20:56:35 -0000 (UTC), Recliner
wrote:

What's wrong with just using 3rd rail beyond Amersham,

More expensive, obsolete, less efficient and it's heading toward 25kV
territory.

Much *cheaper*, surely? Less efficient, yes, but why should it matter
that it's headed towards 25kV territory?

The high cost of DC 3rd rail comes from the need for more complex and far
more frequent substations. You can get a lot of 25 kV line covered from a
single feed.

Like Milton (north of Cambridge) to King's Lynn. Having single feed sections
quite that long has consequences, though.

--
Colin Rosenstiel

In message , at 16:35:40
on Mon, 18 Apr 2016, remarked:

You can get a lot of 25 kV line covered from a
single feed.

Like Milton (north of Cambridge) to King's Lynn. Having single feed sections
quite that long has consequences, though.

As a point of information, it's two single feed sections, with a break
at Littleport. One of the reasons for having just one feed each is that
"the grid" is only available at Cambridge and Kings Lynn, and a new
major substation would be required at Littleport.
--
Roland Perry

On Mon, 18 Apr 2016 16:37:40 -0000 (UTC), bob
wrote:

Recliner wrote:
Charles Ellson wrote:
On Sun, 17 Apr 2016 18:29:31 -0500, Christopher A. Lee
wrote:

On Sun, 17 Apr 2016 20:56:35 -0000 (UTC), Recliner
wrote:


What's wrong with just using 3rd rail beyond Amersham,

More expensive, obsolete, less efficient and it's heading toward 25kV
territory.

Much *cheaper*, surely? Less efficient, yes, but why should it matter that
it's headed towards 25kV territory?

The high cost of DC 3rd rail comes from the need for more complex and far
more frequent substations. You can get a lot of 25 kV line covered from a
single feed.

Robin

Yes, but you have to weigh the cost of that with the cost of raising
bridges and tunnels, and the disruption while doing this.