In article , Charles Ellson
scribeth thus
On Tue, 13 Apr 2010 22:00:22 +0100, tony sayer
wrote:

The WCML modernisation scheme uses (mostly!) 400 V three-phase, but
this has not been a great success owing to the higher currents (and
therefore greater number of sources of supply, known as Principal
Supply Points or PSPs) required.

Ummm.. Rather interesting this but this 400 volt 3 phase supply was
"difficult" in quite what way for signalling purposes?..

As implied above, it requires more transformation points and/or more
copper in the ground. If it replaces a single-phase supply, it also
(assuming 3P+N) doubles the number of wires to be played with (or
stolen) and enables the various "interesting" effects caused by breaks
in the neutral or one phase wire without other conductors being
interrupted.

OK what sort of current draw does a typical signal post, gantry frame,
need then?...

Suppose in that you could include points motors etc...

And that much difference in overall power supplied 650 V single phase
rather then I presume 415 or 440 or was it actually 400 three phase?.

Take your point re more cable required seem the price of copper is on
the up again. Bit on the news of some scrota almost frying himself in a
sub station...
--
Tony Sayer