Roland Perry wrote:
In message , at 13:01:35 on Fri, 6 Jul 2018,
Anna Noyd-Dryver remarked:
Right, here’s some Actual Facts copied from another forum.

quote
As I understand it, it was loss of all signalling power to Streatham
Junction Remote Interlocking area. Ex-Southern Region area signalling
installations usually have three seperate incoming power supply sources,
but in this case there was a catastrophic failure of a part of common
equipment. Other sources state that NR has had to bypass the equipment in
hard wiring to get it working again, but before it could do that it first
had to determine what had caused the original failure, and also monitor the
temporary setup to make sure a hidden fault didn't reoccur and cause even
more damage.

I wonder what it was - they'd have pretty quickly been able to eliminate
back-hoes, smoking substations, and National Grid technicians with
finger trouble.


From the end of my post:

“Signal power feed triple redundant 3 input BUT the changeover swiitch
(single point of failure) was what burnt out”

Apparently the incident is subject to a formal inquiry which will report
back to the NR Board and the DfT.

Edit to add: This just in from GTR journeycheck:

“The electrical supply that maintains this areas signalling system failed.
The failure has been traced to a faulty power supply cable which feeds off
the national grid.”

Well, that must of given the changeover switchgear a good bang
/quote

And from another post in the same place:

“Signal power feed triple redundant 3 input BUT the changeover swiitch
(single point of failure) was what burnt out”

That confirms everything I was saying about the cause, thanks.

It appears to differ from Network Rail's originally announced quick-fix
of generators, unless that's what they used ahead of working out it was
safe to hard-wire one of the two remaining grid feeds.

Thus they still have quite a big project ahead of them - reinstating the
three-way failover equipment (as well as the grid having to make 3/3
rather than 2/3 of the supplies operational).

It also confirms that it’s local equipment, not at the signalling centre
itself.

"A generator has been sourced to isolate the power feed and is
expected to arrive at the signalling centre later this morning.
Once the generator arrives, the situation will be re-assessed."

So it's just a co-incidence that the signalling centre still had power,
yet they needed to locate a generator there to re-energise the local
equipment?

Or that you/we are being over-specific about the terminology used in a
statement that’s probably third-hand when it gets published by someone
who’s not technical staff; and the generator is actually at the site in
Streatham where the problem seems to have occurred, rather than at Three
Bridges ROC which controls the area.


Anna Noyd-Dryver