David Hansen wrote in message . ..

Largely, however there are questions for the railways about whether
a failure on this relatively small scale should have affected
services over such a wide area.


Perhaps a small scale in terms of the number of substations, or even
the geographical area affected, but big in terms of consumers,
megawatts, gigawatt hours and ciruits to which the surface railway are
connected.

From the information I have to hand, we lost the 132kV bar at
Wimbledon at 18:17 and the whole of New Cross and part of Hurst seven
seconds later. We have 5 33kV circuits from Wimbledon rated at 70MVA
and 3 66kV circuits from New Cross rated at 135MVA, thus losing 205MVA
of capacity. Given that these Supergrid sites feed a large area of
South London via 132kV and lower voltage circuits, any connections we
had in that part of London would also have been lost (not that we have
any so connected). There are no other Supergrid sites within London
where a connection could be reasonably made.

We tried to restore supplies from Byfleet, Croydon and Northfleet
132kV supplies, but the voltage drop and charging currents involved
made this a non runner.

From our records, we have never experienced a simultaneous loss of two
supergrid sites in the London area before now and it is not a
contingency we plan for, neither to the Distribution Network Operators
(Used to be called RECs and before that, Electricity Boards).

The great storms of 87 did involve the loss of several Grid Sites in
Sussex and Kent.

Looks like some NGC folk have got some explaining to do.......as have
LUL. I presume that they lost Lots Road BSP (fed from Wimbledon), but
retained Neasden, Mansell St and City Road. As far as I know, the
turbines at Greenwich were not started or did not load (Tim Collins,
Energy Minister said so on the news, so it must be true). Given the
loading conditions on the Grid post fault, it could be that LUL were
prevented from increasing their load from other bulk supplies, which
begs the question of not using Greenwich? I wouldn't mind betting that
the situation between LUL and EDF was uncertain immediately after the
fault, whilst its impact was measured up. Eventually, LUL decided that
it could be long time before supplies could be relied upon that they
would take no chances and evacuate the trains and hey presto 20
minutes later in mid evacuation, the power comes back on.

Richard