A light shines where there was none
 

Initial investigation into the London blackout revel the cause.

http://news.bbc.co.uk/1/hi/england/london/3096098.stm

Wrong equipment caused blackout

An incorrect piece of equipment caused the power cut which plunged much of
London and the South East into darkness, according to a preliminary report
by the National Grid.
The report says it was the largest power cut from the National Grid for 10
years and the company expressed "its deep regret".
About 1,600 trains were stopped and 60% of the London Underground network
was closed, stranding 250,000 during the evening rush hour.
Electricity was restored in 41 minutes and the outage affected 410,000 homes
and businesses, according to the report.
The company says a failed transformer at the Hurst substation near Bexley in
Kent on 28 August, triggered the outage.
Maintenance work
National Grid switched the transformer out of service at 1820 BST and power
was re-routed through other circuits so it could still flow.
But within seven seconds another fault occurred which stopped the flow of
electricity on a 275,000-volt underground cable between the New Cross and
Wimbledon substations.
There are usually two circuits operating between the substations but one was
not functioning because of maintenance work.
According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with the
supply, because of the action taken to compensate for the defective
transformer.
The report adds that this occurred because "an incorrect protection relay
was installed when old equipment was replaced in 2001".
National Grid has so far checked 9,000 out of 45,000 other similar pieces of
equipment across the network and found them to be working as normal.
Blackout trends
The remaining equipment will be checked within four weeks.
But it added: "The incident on the areas of south London was exacerbated by
the loss of supply to the [London] underground and railway services."
It comes as the Department of Trade and Industry and energy regulator Ofgem
said they will appoint specialist consultants to carry out initial
fact-finding investigation into the blackout.
The inquiry will also cover blackouts in the West Midlands last Friday and
power failures in the last five years to see if any trends can be
identified.

A light shines where there was none
 

In message , Cast_Iron
writes
According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with the
supply, because of the action taken to compensate for the defective
transformer.

Finally! Confirmation that the two faults were indeed related. As some
of us insisted (against solid opposition) from the start.
--
Roland Perry

A light shines where there was none
 

On Wed, 10 Sep 2003 14:03:12 +0100, Roland Perry wrote:

In message , Cast_Iron
writes
According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with the
supply, because of the action taken to compensate for the defective
transformer.

Finally! Confirmation that the two faults were indeed related. As some
of us insisted (against solid opposition) from the start.

Not quite true. You conveniently snipped the *real* reason, which was
almost certainly human error.

"According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with
the supply, because of the action taken to compensate for the defective
transformer. The report adds that this occurred because "an incorrect
protection relay was installed when old equipment was replaced in 2001".

The second 'fault' seems to have been a protection malfunction.

The key phrase is perfectly clear and obvious, at least to anyone with a
knowledge of the industry - "an incorrect protection relay was installed
when old equipment was replaced in 2001".

A light shines where there was none
 

On Wed, 10 Sep 2003 15:11:48 +0100, Wanderer
wrote:
On Wed, 10 Sep 2003 14:03:12 +0100, Roland Perry wrote:
In message , Cast_Iron
writes
According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with the
supply, because of the action taken to compensate for the defective
transformer.

Finally! Confirmation that the two faults were indeed related. As some
of us insisted (against solid opposition) from the start.

Not quite true. You conveniently snipped the *real* reason, which was
almost certainly human error.
...
The key phrase is perfectly clear and obvious, at least to anyone with a
knowledge of the industry - "an incorrect protection relay was installed
when old equipment was replaced in 2001".

But triggered by the first fault, no? If the first fault hadn't
occured, neither would the second one (at that particular time).

I guess it all depeneds on how you want to define the chain of
cause-and-effect...

Sam
--
Sam Holloway, Cambridge
www.samholloway.co.uk

A light shines where there was none
 

In message , Wanderer
writes
Finally! Confirmation that the two faults were indeed related. As some
of us insisted (against solid opposition) from the start.

Not quite true. You conveniently snipped the *real* reason, which was
almost certainly human error.

The *reason* for the second outage might have been human error [1], but
the second outage was most definitely *caused* (ie triggered) by the
first. It wasn't an "unrelated" incident.

[1] Although you could argue that it was really caused by failure to
implement a procedure that would have noticed and rectified that human
error.
--
Roland Perry

A light shines where there was none
 

On Wed, 10 Sep 2003 15:17:25 +0100, Sam Holloway wrote:

On Wed, 10 Sep 2003 15:11:48 +0100, Wanderer wrote:
On Wed, 10 Sep 2003 14:03:12 +0100, Roland Perry wrote:
In message , Cast_Iron
writes
According to the report, the second fault occurred because automatic
protection equipment shut off the power thinking there was a fault with the
supply, because of the action taken to compensate for the defective
transformer.


Finally! Confirmation that the two faults were indeed related. As some of
us insisted (against solid opposition) from the start.

Not quite true. You conveniently snipped the *real* reason, which was
almost certainly human error. ... The key phrase is perfectly clear and
obvious, at least to anyone with a knowledge of the industry - "an
incorrect protection relay was installed when old equipment was replaced in
2001".


But triggered by the first fault, no? If the first fault hadn't occured,
neither would the second one (at that particular time).


I guess it all depeneds on how you want to define the chain of
cause-and-effect...

Or whether a member of the public would consider a protection
malfunction to be a genuine fault, in quite the same way that they would
seeing a bloody great hole blown in a cable or a transformer on fire.

Certainly for the purposes of the National Fault reporting scheme it
would be classed as a fault, but the implications in this particular
case are quite far-reaching. If, in the final analysis it can be proven
beyond all reasonable doubt that the outage happened because of
negligence, which seems highly likely, then National Grid could be
liable for substantial damages. Might be time to dispose of the
shares...

A light shines where there was none
 

On Wed, 10 Sep 2003 15:21:57 +0100, Roland Perry wrote:

In message , Wanderer
writes
Finally! Confirmation that the two faults were indeed related. As some
of us insisted (against solid opposition) from the start.

Not quite true. You conveniently snipped the *real* reason, which was
almost certainly human error.

The *reason* for the second outage might have been human error [1], but
the second outage was most definitely *caused* (ie triggered) by the
first. It wasn't an "unrelated" incident.

I'll concede that point, but the discussions that were going on at the
time were much more of the nature that one 'bang' caused another 'bang'
because the circuits were overloaded. It seems *that* wasn't the case.

[1] Although you could argue that it was really caused by failure to
implement a procedure that would have noticed and rectified that human
error.

Yes. Knowing the very strict and thorough commisioning and testing
procedures that once were enforced, one is left wondering whether
corners have been cut since privatisation.

A light shines where there was none
 

Upon the miasma of midnight, a darkling spirit identified as Cast_Iron
breathed:

Initial investigation into the London blackout revel the cause.

http://news.bbc.co.uk/1/hi/england/london/3096098.stm

Wrong equipment caused blackout

Seems to have changed now, but earlier versions of that piece had a
picture of the burnt out wreck of what looked like a very large
transformer with a couple of dodgy-looking air-con cooling units bolted
on to it.

Was that in any way connected with the fault, or just a random pic of
wrecked HV gear?

--
- Pyromancer, speaking for himself.
http://www.inkubus-sukkubus.co.uk -- Pagan Gothic Rock!
http://www.littlematchgirl.co.uk -- Electronic Metal!
http://www.revival.stormshadow.com -- The Gothic Revival.

A light shines where there was none
 

In message , Wanderer
writes
The *reason* for the second outage might have been human error [1], but
the second outage was most definitely *caused* (ie triggered) by the
first. It wasn't an "unrelated" incident.

I'll concede that point, but the discussions that were going on at the
time were much more of the nature that one 'bang' caused another 'bang'
because the circuits were overloaded. It seems *that* wasn't the case.

No, the debate was about whether the second 'bang' was related to the
first in *any* way shape or form. Lots of people insisted it wasn't.

One possible failure mode would be that the first 'bang' caused the
second circuit to overload, and cut out.

If the actual failure mode is the first 'bang' causing the second
circuit to *think* it's overloaded, and cut out, then the difference is
entirely academic to those people sat in the ensuing darkness.
--
Roland Perry

A light shines where there was none
 

Roland Perry said:

The *reason* for the second outage might have been human error
[1], but the second outage was most definitely *caused* (ie
triggered) by the first. It wasn't an "unrelated" incident.

[1] Although you could argue that it was really caused by failure
to implement a procedure that would have noticed and rectified
that human error.

So much for redundancy as a method of protection. Doesn't anybody
test these things?

--
=============================================

Chris Game chrisgame@!yahoo!dotcodotuk
=============================================