Possums on the list?
Poor, slow moving, tree climbing little bastards leave their carcasses all over the place.
Folks relying on mains-powered alarm clocks had an excellent excuse for turning up late for work on Friday in Seattle – after a raccoon knocked out power to a chunk of the northwest US city. On Thursday evening, the marauding mammal made its way onto the property of municipal power generating company Seattle City Light and, as …
A customer from a previous life was a telco who also manages the power grid. They use substations for placing of comms gear, and underground ducts and poles which are shared with power to install fibre and other cables.
One day I had to go to a substation site to do some work on the comms gear. As you can imaging, in this environment there is a substantial induction process to work around multiple 66kV systems, cabling and the like. Unfortunately for a common ringtail possum, it was not privy to said induction and I saw the remnants of one across the terminals of the primary of a transformer within the substation.
All that was left looked like a tube of grey fur with nothing inside of it. It almost looked as though it was something you would need made or milled somehow. It didn't even look "damaged", just a hollow grey furry tube.
This mishap did not cause any blackouts nor do I think anything tripped (not that I'm aware). I am guessing (I'm not an electrical engineer that controls power grids, just a network architect commsy guy) that the arc was within tolerances for this system and it was able to carry on.
If an animal or tree branch causes a short-circuit fault on a high voltage line like this, the system probably will temporarily trip (whether it does depend on the fault level but also the time a given fault level is present) but you have automatic circuit reclosers (ACRs) on such lines which will deliberately close onto the fault, and try 2-4 times to do so. Simply because, the amount of energy going through it will likely frazzle the thing to a crisp to the point where it stops being a conductor anymore, and there is no further problem to the system - most faults are transient, not permanent. After a few tries though, it will stay off.
Considering it wasn't that long ago (mid-June) that a raccoon was climbing a 20+ story office building in Minnesota you might want to rethink that very low wall.
When we build the wall to keep the Americans out of Canada we will ensure that there are plenty of "cat flaps" to allow our raccoons continued access to the US so that they can keep up their ongoing campaign of mayhem.
My experience with raccoons:
Steps on a rat trap - curses and continues destroying vegetable garden.
Hit by a flying bar stool when it walks into the kitchen - leaves then comes back in 15 seconds to see if you're still mad.
Hit in the face full-force with a hardwood club, knocking it out of the kitchen so hard that it slams into the yard fence - wimpers, curses, comes back tomorrow.
I'm not confident that a flash of a few MJ actually killed it. It's probably just resting until it cools down.
2 fighting with Dobermann:
dog owner assists pet - ignored
dog owner returns w baseball bat? raccoons leave, unhurriedly
They look cute, but getting bitten by one means rabies shots and the ones most seen by tourists in Stanley Park are right next to a cliff where people have died falling.
Ours was very dead.
We had a power outage during good weather a few years back. We waited a bit but we were still blacked out so called the power company after making sue we didn't have a tripped main breaker in the box or fuse on the pole. Power company operator said "are you sure? nobody else has reported a problem."
When they sent someone to check on it, he saw the breaker feeding the pole transformer had tripped. And while he was up in the boom truck fixing it, he looked down and said. "There's your problem" as pointed at the dead raccoon in the tall grass by the power pole.
A few years later they installed a band of metal flashing around the power poles up near the wires. I don't know for sure, but it would seem to sized right to make a good squirrel and raccoon guard.
"A few years later they installed a band of metal flashing around the power poles up near the wires"
In New Zealand _EVERY_ pole has one of these. Tasmanian ringtailed possums like to climb poles and they really don't know how to conduct themselves once they reach the wires.
Induced electrical fields, winding numbers, inverse square law, ... thinking of things from the squirrel's point of view, a minor hair-raising incident followed by a slightly-painful static discharge is probably going to be enough to induce a kind of negative magnetism against the HV air gap that was going to be its original LZ. Like an RFID bug zapper.
"If only there was a way we could build a structure without room for these animals to get in."
In my experience it's virtually impossible to stop them getting in, but you can increase the spacings so they can't get across the conductors or between conductors/earth.
Alternatively (as mentioned above) you can arrange the supply to be beefy enough that it just shrugs off the arc and carries on.
At long last an opportunity to recount something the lovely Ivana & I encountered while holidaying in Fort Lauderdale.
We had some time to kill and decided to go for a walk in the Hugh Taylor Birch state park while we were there. On the road up to the gates there are some signs saying 'Don't feed the raccoons'. As Brits, we had never seen a raccoon so we asked the ranger at the gate if it was likely that we would see any of these creatures that we must not feed..
She replied that as it was early evening it might be possible as they would be waking up to go foraging in the next hour or so. Anyway after an hour we hadn't seen a raccoon, just some birds and the odd roller-blader and our time was up for going to retrieve the kids so we set off walking back.
As we passed the ranger on the way our she asked if we had seen one. Perhap's another half hour?
We didn't have the time so we wished her good day and set off down the road back to East Sunrise Blvd.
As we were walking down, a creature akin to a young badger in size & colour came out of the undergrowth, crossed the entrance road and disappeared into the undergrowth on the other side about 30-40m ahead of us. No sooner had it disappeared than several more appeared crossing the road randomly ahead of us and going into the undergrowth.
At last we've seen a raccoon - several raccoons. It did cross our minds to wonder why they were all crossing the road at the same time and in the same direction. Logic said food, but what do we know about raccoon behaviour?
Where the park entrance road meets the boulevard there is a set of stop lights and a wide grass verge between the footpath and the roadway.
There was a queue of cars waiting at the red light as we came on to the boulevard.
On the grass verge were half a dozen or more raccoons lined up begging.
One of those sights the both of us will never forget.
There's no need to put the signs up in the park, the clever raccoons get take-aways delivered!
I was a transmission operator in the Deep South for over 3 years and animal caused black outs on a very regular basis. Squirrels, snakes, turkeys, raccoons, possums, etc etc..all get up on outdoor Distribution and Transmission buses shorting phases and causing "differential" trips on the breakers.
That story is a classic - I've just been quietly crying with laughter at my desk, getting funny looks from the boss:
"A metal thief who was seriously injured after sawing through a cable carrying 11,000 volts has been ordered to carry out 140 hours of unpaid work. [...] Paisley Sheriff Court heard how Durnan was left "looking like the professor from the Back To The Future movie". [...] There was an explosion as he sawed through the cable at about 06:50. [...] Despite being severely injured, Durnan managed to go to a nearby house for help and was unable to talk."
Can you imagine a mute Doc Brown showing up on your doorstep, smouldering away? That does suggest a real prize though - connecting politicians and irritating schlebs to an 11kV line might stop them talking also.
One of my high school classmates had a notion for copper theft in the Colorado foothills. At each end of a cable, a man with a sufficient cutter; on an agreed signal, each makes a simultaneous cut. It did not sound practical. I don't think he ever tried to put this into practice, for I didn't hear of him suffering death or injury in the several years before I left down. He was quite serious about the idea, though.
Seattle is lucky. Last weekend, about 18,000 houses in my city as well as the municipal water pumps lost power for 3-4 hours, and so far all PG&E has told people is that the incident somehow involved a bird. (How that was possible, or whether it should even be possible in the first place, hasn't been explained yet.)
It takes a relatively small fraction of the energy available to completely toast an animal.
The problem is that they light an arc, which can conduct that power.
The reason for the gunpowder in a fuse is to blow out the arc that forms. There are other designs, and they use physics that few of us have encountered in our daily lives (e.g. a magnetic blow-out).
We don't actually own the lives of every creature on earth - this was a damn disaster for a poor raccoon attempting to live it's life around pesky damn humans who are pillaging the entire planet and billowing pollution and trash absolutely everywhere. The sooner we realise we live in a spaceship, the better. It's too fukcing late of course. We'll be fukced fairly soonish like the dinosaurs before us.
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