On Feb 15, 8:09*pm, (Colin Rosenstiel) wrote:
In article
,



(John B) wrote:
On 15 Feb, 13:59, (Colin Rosenstiel) wrote:
How do they cope with 6-car 313 trains on the GN then?

The power supply on the GN can cope with them. The power supply on
the DC lines can't (according to a recent thread).

But the GN has DC lines from Drayton Park to Moorgate. The trains are
limited to 30 MPH (series only) but I thought that was because of the
tunnels, not the power supply.

It's not that DC is inherently incapable (see: 12-car Desiros on SWT,
which draw more than 2x the power of a 6-car 313), it's that the
specific actual DC power system, substations, cabling, etc that was
installed on the North London Railway in 1916, even with whatever
upgrading it's received since, is not capable. The system installed in
the GN in the mid-1970s was much more powerful...

[see also: electric trains north of Cambridge or between Leeds and
Skipton. 25kV AC is perfectly capable of handling TGVs and massive
freight trains, but the systems installed in the 1980s can only handle
a couple of EMU...]

But the power supply North of Queen's Park could handle 1680HP 1938TS. So
why not a mere 6 cars of class 313?

--
Colin Rosenstiel

I think that there might be some mixing of problems here. I think that
the North London line is the route limited to 3 car 313s, this was
electrified before the DC lines even existed (in 1916). The closure of
Broad Street and extension to North Woolwich was done on the cheap and
I think this was the part with supply problems. With the closure
beyond Stratford and the electrification of the new platforms there
with AC, I think that any restriction will disappear, as most of the
route will then be AC electrified. The DC Lines from Euston don't have
such the restriction, as they were a busier railway, designed to cope
with the Bakerloo stock all the way to Watford. However, there may
still be a problem of peak current drawn and things may have changed
with any re-equiping of the power supply.