On 29/07/18 19:12, R.Wieser wrote:
> Steve,
>
>>>> Now the 132KV lines make sense...
>>>
>>> If it would be DC, not really. :-)
>>
>> Very high power under water links are often DC viz:
>
> Yep.  Not because of it being a generic usable method, but because the need
> for DC - not influencing magnetic compasses - overruled the cost for it.
>

Completely wrong.


Got nothing to do with compassess and everything to do with te fact that
the capacitance to sea water via a few cm of insulation is WAY higher
then the capacitance to ground of conductors strung 20 m up in the air.

That wouldnt matter if the cinductors had zero resistance - out of phase
current is lossless current - but conductors HAVE resistanbce, and that
menas there are losses - serious extra losses - in the cables.


> But I must say I'm rather surprised to see that new ones are being laid even
> now, in 2018 ...   I though that magnetic compasses where all but obsoleted,
> especially in this day-and-age where even a $30 phone has a GPS reciever.
>

If your original premise is sheer nonsense any facts you deduce from it
will be nonsense too.


HVDC is more efficient  for long hauls where AC cable losses start to
become significant.

HVDC makes sense when you need AC->DC->AC conversion anyway to connect
grids that are not synchronised. Or when your generators are not synched
- as in an offshore windfarm.

Or when your solar panels produce DC...

What has happened is that power semicinductors of serious speed and
power are now wavilable to replece te original mercury arc valves used
in HVDC, and its therefore become a lot easier and cheaper to implement.

And the need for it rises as more and more grids seek to swap problems
with each other to make their renewable energy fantasises work.



> Regards,
> Rudy Wieser
>
>


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