I've just had a call back from the power company about our recent power cut (
https://www.eevblog.com/forum/chat/south-australia-has-no-power/msg1037841/#msg1037841). It turns out the failure was caused by a tractor driver using a hedge cutting flail in the field where the pole is which carries the 11kV overhead line via reclosers down to the short run of underground cable to the transformer
. It looks like he didn't
quite go through the cable (running down the pole) at the time but did enough damage to make it fail next day. He was working in the field that backs on to my garden, and I saw him at it, after dark, using tractor lighting. I think he had a lucky escape!
In other news, I can confirm the alarm backup battery is thoroughly dead. No protection against over discharge.
Why FLISR and SCADA systems did not isolate the failed 11kV (which is a relatively low power, low voltage wire) from the system?
Even though, the SIL of transformer and line should not allow so much power to flow from backbone grid to fault point that causes a national blackout.
Did you mean 110kV?
Errrr... Different power failure, in England. It just happened while I was in the process of reading the South Australia thread.
Don't worry about the joys of living in the country. I'm in the middle of a city and they have been working for almost a week already to rebuild/replace a blown power distribution transformer. Meanwhile a large diesel generator is running to power the streets the transformer is feeding. I assume they'll announce another power outage when they are going to swap the power from the generator back to the mains...
Around 2009 the minisub across the park had a minor event on the 11kV feeder side ( cue the fire and the loud sounds till the Old Fort substation finally tripped the loop, and the fire brigade arriving to put out the inferno of burning fibreglass), and it was replaced with a refurbished one within 24 hours, though the grid loop was isolated at the 2 substations either side within 6 hours. Then last year the copper thieves went into the substation where I get a feed ( twice) and there was no power for around 2 days while it was repaired.
Then last year the copper thieves went into the substation where I get a feed ( twice) and there was no power for around 2 days while it was repaired.
We get a bit of that too, but mainly the earth wires from pole mounted transformers to the ground earth field near the base of the pole. It really irks me that the mains earth system can be so easily and dangerously compromised.
Of late these cable are being replaced (as stolen) with copper plated steel bearing a label "Not Copper".
It got so bad that all the scrappy's insisted on proof of identity when submitting quantities of "network" cabling for recycling.
They solved that one here as well, using a copper plated spring steel conductor in the bundle. The scrap yards will not take the cable as the spring steel will break the cutters they use on cable to get them short enough to bale, and removing the steel from the cable is a long job. plus it is near impossible to cut with either a hacksaw or bolt cutters.
I gave a suggestion to simply use a 25mm diameter steel cable instead, it will still do the job, but is a lot harder to cut.
Then last year the copper thieves went into the substation where I get a feed ( twice) and there was no power for around 2 days while it was repaired.
We get a bit of that too, but mainly the earth wires from pole mounted transformers to the ground earth field near the base of the pole. It really irks me that the mains earth system can be so easily and dangerously compromised.
Of late these cable are being replaced (as stolen) with copper plated steel bearing a label "Not Copper".
It got so bad that all the scrappy's insisted on proof of identity when submitting quantities of "network" cabling for recycling.
There is an auto salvage yard not far from me that takes in recycling. We saved up a bunch of aluminium cans and I brought 3 contractor trash bags full. They took a photocopy of my license and I had a form to fill out, all for $20. Now that stuff just goes in the recycle bin that is collected every Friday. Anything I can't be arsed to 'officially' recycle, I put on the swale the night before recycling day. Someone will save me the trouble of doing it. A few years ago I put a dead 60" rear projection TV out there, went out and ran errands, came back in an hour and a half and it was gone. People will grab up anything that you put out.