Ron Lowe wrote:
"Dave Plowman (News)" wrote in message
...

snip

Aside:
I just got back from Namibia and Botswana.
I was peering at their overhead 11Kv distributution system.
All very similar to here.
With an interesting exception.

There were long runs of *single* conductor HV on poles, along the
rural gravel roads.
There were transformers dotted around on poles, feeding individual
premises. I never got a good look at one of these transformers.
Now, how does that work?
They must be using TT earth as an actual current return, on the HV
side, as far as I can see.
I wonder how they make the local HV earth connection with
sufficiently low Z in the very dry earth?

Further confirmation was at one lodge, where an old transformer was
laying outside the services building. ( I'm sure everyone thought I
was crazy, polishing the muck of the data plate of an old transformer
in the corner.. ) The rating plate had the single phase primary as
6.3Kv, which is consistent with the Phase-N voltage of an 11Kv
Phase-Phase system. There must have been 1:1 Star-Delta
transformers someplace on the main network, where the normal 11 KV
3-wire delta distribution spurred off to a star 11Kv 3-wire +N (
6.3Kv per phase-N ), and the N was grounded. Only the single phase
was sent on the wire.
Interesting to me, anyway.

Uses the Earth (the real solid one you stand on) for the return. Works well
most of the time except when the weather is very dry then you get brown outs
................. (well you would if there is no rain!)

--
Mark BR