On 28/07/2014 08:23, harryagain wrote:
"The Natural Philosopher" wrote in message
...
On 27/07/14 23:49, Tim Watts wrote:
I thought it was more the issue that you cannot phase lock France and
the UK? So DC is a natural choice if you have to re-invert it. And if
you have to do that, might as well transmit in DC too.

Not saying your reason is not a good reason - I just thought it was a
secondary reason to a fairly immutable primary problem.

No. I visited the first link to france at the UK end and the issue is
primarily one of losses

'we can draw an arc for 30 minutes off the capacitance in that cable'

To drive that capacitance takes a LOT of out of phase current and that
suffers resistive losses.

Big ones


Drivel
Capacitance does not cause any losses.
It does cause phase shift and instability.
When the cable is under load it will actually help with phase shift.
Only resistance causes losses.

Whenever current is passing through any imperfect conductor.

On an AC transmission line, current is constantly being drawn to alter
the voltage across the line capacitance to earth. So the capacitance is
the cause of the resistive losses.

Loading a cable has no effect on the phase shift you mention, unless
that load is reactive, and depending on whether it is inductive or
capacitive, it can then either worsen or improve the situation.

Where exactly is this arc drawn for 30 minutes and for what purpose.?


The arc *can* be drawn by using the DC charge stored in the cable. No
claim was made that it ever had been drawn either deliberately or
otherwise, though it's the kind of trick that installation engineers
have been known to pull as a joke, or that happens when things go wrong
when commissioning plant of this sort.

The greens are planning to use this effect to store energy in their
proposed long distance links for their beloved European renewables
Supergrid, all of which *you* have mentioned here in the past.

Should we add memory loss to your minimal comprehension skills?

--
Tciao for Now!

John.