In article , harryagain
wrote:

"John Williamson" wrote in message
...
wrote:
I don't really understand why we don't go for 3 phase at say 800V.
Let's face it: even 230V is well into the lethal zone so going higher
isn't going to be any more dangerous. Plus 800 is still low enough
not to arc or flashover - given remotely adequate insulation. And
just think of the saving in terms of conductor! Given the price of
copper (notwithstanding it's slipped back lately) I'd have thought
pushing up the supply voltages would be obvious thing to do from the
pov of conserving natural resources.

One problem is the huge installed base of equipment, including cable
that is rated at the current voltages. Current insulation standards
sometimes stuggle with the current voltages, shown by exploding cables
as frequently reported in this newsgroup.

Another reason is that along every street in the country is a set of
three cables carrying the current voltages of 230V to earth, and 400V
(+-) between them. To have 800V available, the powers that be would
need to run new cables from new substations to only those users
wanting 800V.

Another way to save money on the grid would be to increase the
frequency, allowing the use of smaller transformers for the same
power. The same objections apply, although aerospace applications
often use 400Hz AC for this reason.

In days of yore as the national grid was being created, the were auto
trnasformers between areas of different local voltages as a temporary
thing. The electricity boards were responsible for collecting up all
appliances and converting to the new voltage. Vast job even back then.
Pre and post war.


certainly up to 1962, Cambridge town was supplied wth 200v mains. Sellers
of electrical goods needed to supply the right ones for use there. My 200v
coffee pot survived about 1 year on 240v elsewhere, my soldering iron -
quite a bit longer.

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