"Chaos at London Victoria" 05/07/2018

[whole diary]

[Electric train]

Thanks for the detailed reply.
I do however find it very surprising that a high voltage grid outage was behind this failure.

High voltage National Grid circuits are usually duplicated and loss of supply therefore very rare from this cause. I  recall a failure some years ago when two almost simultaneous faults blacked out a large part of greater London and North Kent.

However in this case I don't recall any large scale outages to ordinary consumers. It is of course possible that the railway 33Kv system is reliant on a single high voltage grid connection which would be more vulnerable.
In such circumstances I would expect that the low voltage DNO^▸ (Distribution Network Operator) supplies would still be available.

What you may (or may not) notice occasionally is the lights in your house or work place dip, just for a fraction of a second; this can happens when there is a fault on the transmission network or 132kV  33 kV distribution network.


For most people it does not effect them, it may mean your PC reboots, clock on a cook reset etc for some of the traction power systems with signalling supplies derived from the these are designed to fail safe even for a 200mS dip; most times systems self reset within 30 seconds or so, although a train driver may see a black signal or one which has changed aspect to danger, they will stop their train.

All of this adds up from what was 200mS to many minutes of delay.  What happened last week was signal power reset within 2 seconds and most signalling systems reset however there were a few places where the signalling failed to reset and techs had to visit site.

[broadgage]

Thanks for the update.
It does however seem to be a poor design that is so vulnerable to events that went largely unnoticed outside the railway.

[Electric train]

Thanks for the update.
It does however seem to be a poor design that is so vulnerable to events that went largely unnoticed outside the railway.

The fact is the signal power was designed in the area effected last week in the 1980's for that era signalling and interlocking; over the years Signalling have enhanced / upgraded equipment but the power supply at times is seen as just that its a power supply, the view being "its been reliable over the years its never caused problems, the funds are better spent elsewhere where there is a problem"


UPS are being installed, they are expensive to install and to maintain and the former Southern Region has a lot of signal power supply points so it takes time, often waiting for the next major resignalling project or perhaps re-lock if its a big enough project