OT: How does power supply company locate a fault?

I'm just interested in how Western Power, for example, detemines where a fault lies when a power outage occurs. They seem to pinpoint it very accurately within a few minutes, or even seconds. For example, this morning, suddenly, there were three brief power outages in ten minutes, each lasting just a few seconds. But when I rang the fault number the adviser already knew about the fault, which was apparently on a high voltage line, and the outages happened as a result of re-routing the electricity supply.

Is the monitoring equipment so sophisticated nowadays that many/most outages are picked up from the control consoles? I can recall back in

2005 when the electricity company after a storm was out in a rugged Land Rover scanning the power cables bit by bit.

Our supply here in rural Lincs has improved considerably over the past few years, but am I glad I got UPSs for both PCs many years ago! They've kicked in many times.

MM

Reply to
MM
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Automatic re-closing switches and a supervisory control system.

Reply to
Ash Burton

By deriving the impedance during the the fault, knowing the line construction, the type of fault (single phase to earth phase to phase or three phase to earth) and then doing a bit of maths.

With modern kit a few seconds after a fault the derived distance to fault figure is either on the fault recorder at both ends of the circuit ready to be accessed remotely by an engineer or it is displayed at the control location.

Reply to
The Other Mike

They don't use RF techniques like time domain reflectometry then? I suppose it is easier with twisted pairs.

Reply to
Roger Hayter

Auto recloser being tripped and reseting, normally a bit of tree getting too close touching the line and gets vapourised so generally only one brief outage. Just as well the three you had were well spaced if an auto recloser trips more than 3 times in a few minutes it locks out, the fault located and fixed and the recloser manually reset.

Auto reclosers phone home when they trip/lockout.

Not sure I believe that. If a fault around here means that sections of line are feed from a different place by opening normally closed air switches and closeing normally open ones. When it comes to restoring normallity the open switches are closed before the closed ones are opened meaning no interuption to supply. Well almost, after one restoration of normality the lights where flickering away like anything, rang the DNO, engineers at the door a few minutes later, know what that is, off they go, couple of minutes later the power goes for a second or so and comes back solid. I guess an air switch hadn't closed properly and needed re making.

Poles, lines and insulators don't phone home when they fail. They'll know which sections of line the fault(s) are in by which auto recloser has tripped/locked out but not exactly where the fault is. They do have some cunning device that measures ground currents/voltages when the line is energised and the auto recloser trips that gives an indication of how close it is to a fault. Failing that or a report from some one that an insulator is arcing over or a line is down, the only way to find a fault is to walk the line.

Reply to
Dave Liquorice

Slightly OT, but generally, with electricity the suppliers *can* know almost "everything". Certainly where faults/outages are.

It's a source of endless amazement that people are still stupid enough to try and steal electricity by fiddling with the meter*. After all, the formula "Energy generated = energy charged for + network losses" is never going to change.

*And it's no use taking the modification off when the meters read ... they can detect it regardless.
Reply to
Jethro_uk

When I was a student with SESEB in 1959 fault reporting existed on underground cables.

Reply to
charles

Well there are many things now done. Firstly of course if power does go down, its not rocket science if power is at one end and not the other and yes, things are monitored and obviously when this happens a section is isolated and an attempt is made to route around it. This normally works if its a small area, but larger areas of course are protected in that you cannot overload a section any more, the logic stops that being possible, in theory at least. Also some power companies use a thermal imaging device on a helicopter to regularly look at power lines as odd heat increases spells possible failure and they can fix it before it becomes an issue.

Underground cables are the most difficult of course as there is no way to find where the break is unless there is a tell tale crater in the ground nearby of course!

Brian

Reply to
Brian Gaff

But then how many times will an underground cable develop a fault, as opposed to overhead lines ?

(FTAOD, having a JCB bucket divide a cable in two is now "a fault").

Reply to
Jethro_uk

In addition to all the other answers, when it comes to finding underground faults they use a unit called a thumper. Basically a big dangerous capacitor. They connect it to the cable and see where the ground jumps.

Reply to
philipuk

on 23/01/2018, Brian Gaff supposed :

Actually there is - They can send a pulse down a cable then measure the time for the pulse to be reflected. Time = distance to fault.

It is commonly used on telephone cables too.

Reply to
Harry Bloomfield

For modest amounts of "Fiddling" I'd expect it would go undetected provided the 'Fiddler' has left no obvious visible signs of their fiddling activity.

The first house I owned had a meter that very slowly ran backwards when everything was switched off. It was only the equivalent of running a 14 watt load for free as far as I can remember calculating it. It must have halved the cost of running the fridge which used a 30 or 40 watt heating element to drive the absorption cooling cycle (an electric version of a gas powered fridge if you will).

I realised it wasn't enough of an 'anomaly' to concern the supplier (MANWEB as it was before the madness of Thatcherism destroyed the economic, vampire free, running of the nation's vital services) so just accepted "The Free Gift", modest as it was - "Every little helps!". :-)

Reply to
Johnny B Good

Fascinating. Thanks.

MM

Reply to
MM

Also fascinating. There was another 10 second outage this afternoon. Just the one this time (but long enough for me to have to set the oven clock AGAIN!).

Maybe this was when they were re-routing back from the failed high voltage line this morning, which had since been repaired.

Four outages in one day! Must be a record.

MM

Reply to
MM

Yes, my brother warned me about capacitors when I started dabbling in electronic circuits. He became an electrical engineer. I was a motor fitter.

MM

Reply to
MM

The woman on the phone at Western Power could say precisely that they were aware of the fault and it had affected 218 properties! Pretty f.... amazing, if you ask me.

MM

Reply to
MM

That sounds fun.

Stick this in YouTube search

"electricity cable thumper"

for examples and other cable fault kit.

Reply to
newshound

Jethro_uk pretended :

They can measure consumption figures at the consumers meter, they will know what they are feeding down the main supply cable to all of those meters, but none of the measurement systems will have a margin of error.

The error margin means small amounts of theft will not show up. If it did, then those turning a normal domestic house into a place to grow the illegal plants, would be easily spotted - they are not, which is why the police rely on heat signatures, helicoptors and neighbours reporting the smells.

Reply to
Harry Bloomfield

We had an outage of a bit over an hour the other day. They said it was a fault, but they were splicing new cables in at the time...

I wasn't in; the UPS units handled it nicely. One lightly loaded one kept going throughout; the other two neatly shut down everything to which they were connected just before the batteries gave out! A total of eight computers.

Reply to
Bob Eager

Time domain reflectometer.

Will spot an anomaly in any cable within a few microseconds of deployment

Reply to
The Natural Philosopher

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