"Tim Streater" wrote in message
.. .
In article , NY
wrote:

"The Natural Philosopher" wrote in message
news
On 13/03/18 12:13, NY wrote:
What were the reasons for the UK having its own grid, with a *DC*
connection to mainland Europe? Was it just that the UK wasn't part of
Europe at the time, or was there another more technical, less political
reason?

Well you see its this odd and not very political thing called GEOGRAPHY.
You maye have heard of it although its not as fashoinable as gay
marriage, but what it means is that if you walked all round the COAST
like that ponce on TV you find that is water on every side!

And that means its a long way to string pylons in shipping lanes so teh
GB grid is naturally isolated and always was, since ints inception in
IIRC the 1930s

Yes, that's a very good reason for not having *any* connection between UK
and mainland Europe.

No, you run it on the seabed, or perhaps through the tunnel.

But given that there *is* a connection, is there a reason why it is DC
rather than AC?

Capacitance losses.

Ah. Yes that makes sense. 20 miles of overhead line would be fine (*) but 20
miles of coaxial cable will have significant capacitance.

As a matter of interest, how do they avoid the problem when overhead lines
are converted to run underground, eg when passing through an area of
outstanding natural beauty?

Do underground lines run as a single cable with three conductors (for three
phases) surrounded by a common earth, or are they three separate lines, each
with its own earth screen? Indeed is it necessary to have an earth screen as
long as the wires are suitably insulated?



(*) Apart from the "little" matter of suspending the wires across the
Channel :-)