To go off on a complete tangent does any one know if the 3000 volt
3 phase system the Metropolitan railway considered would have been
straightfoward to install, or would that have required some tunnel
alterations.

Mention is made however of Ganz which IMU infers 3-phase but according
to Wonkypaedia :-
http://en.wikipedia.org/wiki/K%C3%A1...A1n_Kand%C3%B3
there was also a modified system using a single-phase OH supply with
conversion to 3-phase on the locomotive used in Hungary; the wlv.ac.uk
article referred to above mentions the "an overhead conductor" so the
Met. might only have wanted one piece of wet string.

No, it was two overhead wires. The following is from "A History
of London Transport" (Barker and Robbins), volume 2, pages 58
and 75. The Metropolitan and District issued a call for tenders for
electrifying their lines and hired two consultants, Sir William Preece
and Thomas Parker, to examine the tenders.

# Preece and Parker... on 9 January 1901, reported that the thought
# that Ganz's seemed the most suitable but felt that they ought to
# inspect the Ganz system before making a definite recommendation.
# They went to Budapest and reported to the joint committee on
# 7 February 1901 that they were satisfied. It was therefore
# decided to recommend the Ganz system to the two companies.
# This agreed recommendation came as a bombshell, for the Ganz
# tender was for a 3,000-volt three-phase a.c. system fed to the
# trains from two overhead wires, quite unlike anything which had
# been tried out by the underground companies so far and, indeed,
# different from anything which had been in successful commercial
# operation up to that time anywhere in the world.
...
# This had the attraction of economizing in transformer and
# converting plant but the disadvantage of requiring twin overhead
# wires with a potential difference of 3,000 volts between them
# and between each of them and earth. These overhead wires would
# be difficult to install in underground tunnels and, should either
# of them be brought down when the trains had started to run, they
# might endanger human life by fire or electric shock and would
# certainly lead to long interruptions in service. There was
# the further disadvantage that alternating current motors had
# a much poorer starting torque, a very important consideration
# on a system having numerous stations and frequent stops. And,
# most important of all, the Ganz system had not at that time been
# tried out anywhere in the world under commercial conditions,
# though it had been shown to be technically feasible on a trial
# stretch of open line about a mile long...

"Difficult to install in tunnels". That sounds to me as though
they felt there was enough clearance for 3,000-volt overhead
wiring, but only just.

Note incidentally that there was 3,000 volts between each wire and
earth as well as between the two wires. That's obviously because
the earthed running rails were to be used as the third phase, just
as they are a conductor when used with third rail (and not fourth)
or single-wire overhead. In a 3-phase system with 3 separate
conductors, they only need to be at 3,000/sqrt(3) = 1,732 volts
relative to earth to have 3,000 volts between any two of them.

The book includes a long footnote which says, among other things,
that the first use of the Ganz system in commercial service was on
the Valtellina line near Lake Como in September 1902; and that
technical details of the system and an illustration of a Valtellina
line locomotive can be found in "History of the Electric Locomotive"
(1969) by F.J.G. Haut.
--
Mark Brader, Toronto | This is Programming as a True Art Form, where style
| is more important than correctness... --Pontus Hedman

My text in this article is in the public domain.

Mark Brader:
The book includes a long footnote which says, among other things,
that the first use of the Ganz system in commercial service was on
the Valtellina line near Lake Como in September 1902; and that
technical details of the system and an illustration of a Valtellina
line locomotive can be found in "History of the Electric Locomotive"
(1969) by F.J.G. Haut.

Looking around on the Web for photos showing such a locomotive,
I only find this one, although it's on several web pages:

http://en.wikipedia.org/wiki/File:Ka...an_mozdony.jpg

So I suspect it's the same one as in Haut's book. Anyway, the
interesting thing is the collector that contacts the overhead wires,
which looks more like a big bow collector than anything else --
one collector contacting both wires. Obviously there must have
two separate contacts on that horizontal bar, with insulation
between them.

Also note how high the arm is above the locomotive. You'd never
fit that thing into a Metropolitan or District tunnel. They must
have had a different sort of collector in mind.

This page shows that photo and a couple of other ones of the Ganz
3-phase system, before moving on to related subjects. They all
appear to have those high collectors.

http://erojr.home.cern.ch/erojr/cont...pe/kanprot.htm
--
Mark Brader, Toronto | "What Europe needs is a fresh, unused mind."
| -- Foreign Correspondent

My text in this article is in the public domain.

On Oct 26, 11:22*pm, (Mark Brader) wrote:

one collector contacting both wires. *Obviously there must have
two separate contacts on that horizontal bar, with insulation
between them.


Also note how high the arm is above the locomotive. *You'd never
fit that thing into a Metropolitan or District tunnel. *They must
have had a different sort of collector in mind.


I've never really looked into the three phase ideas of the Met but I'd
always thought they were looking at the three phase "two wire" system
(i.e. three phases of two conductors and one running rail return) not
with overhead wires but rails, with lower supply voltage than Ganz.
Conductor rails something like the centre and outer rail (like todays
DC) would be the equivalent to Ganz two wires, and the running rails
the return in the same way as Ganz. That way you don't need to expand
tunnels. My interpretation of "not suitable for tunnels" was not
something about not enough wire clearances but one of having all
track rails in a three phase system at a voltage too high for exposed
ground level conductors. Like I said its not something I looked into,
so maybe I misunderstood the whole thing.

If you really wanted to run three phase for the tubes I suggest you
simply use a side contract pickup for all three phases - its complex
at points and crossings but providing one car of the set is in contact
you still have power, and thats no different to a lot of DC section
gaps on todays tube.

--
Nick

Mark Brader:
Also note how high the arm is above the locomotive. You'd never
fit that thing into a Metropolitan or District tunnel. They must
have had a different sort of collector in mind.

"Nick":
I've never really looked into the three phase ideas of the Met but I'd
always thought they were looking at the three phase "two wire" system
...not with overhead wires but rails, with lower supply voltage than Ganz.

As I indicated in my previous posting, "A History of London Transport"
is quite explicit that it was Ganz and overhead wires.
--
Mark Brader, Toronto | "Something doesn't become ethical just because
| you can get away with it." --Barry Margolin

On Sat, 27 Oct 2012 01:52:33 +0100, wrote:

On Fri, 26 Oct 2012 17:22:33 -0500, (Mark Brader) wrote:

Mark Brader:

the Valtellina line near Lake Como in September 1902; and that
technical details of the system and an illustration of a Valtellina
line locomotive can be found in "History of the Electric Locomotive"
(1969) by F.J.G. Haut.

Looking around on the Web for photos showing such a locomotive,
I only find this one, although it's on several web pages:

http://en.wikipedia.org/wiki/File:Ka...an_mozdony.jpg

So I suspect it's the same one as in Haut's book. Anyway, the
interesting thing is the collector that contacts the overhead wires,

Also note how high the arm is above the locomotive. You'd never
fit that thing into a Metropolitan or District tunnel. They must
have had a different sort of collector in mind.

Bonnet mounted collectors have been used on some electric locos where
there were limited clearances.
http://www.flickr.com/photos/45127721@N05/6581147453
is an example on a UK industrial system that survived till the late
1980's.
In a tunnel setting arcing from such a low collector in the drivers
view can cause disruption to vision and I shouldn't think it would do
much for the health of the eyes either.

That can be avoided by using the rear collector if two are fitted as
on the Italian locomotives in :-
http://en.wikipedia.org/wiki/Three-p...lectrification

On the subject of Italy, I hadn't realised they were still using
3-phase into the 1970s :-
http://www.photorail.com/phr1-leFS/e432.htm
(with an interesting effect caused by smoke/steam/fumes coming from a
"chimney" at one end)

Trolley poles would be another possibility. Used in the original
Cascades tunnel electrification in the United States which was a 3
phase system.

Distance memory's of trolley buses and dewirements suggest they would
be impractical on a system with many junctions like the Metropolitan
even though a railed vehicle would have less tendency to pull the
booms offline.

G.Harman