How could a squirrel do so much damage?

[NeoPTLD]

So, about 10,000 people lost power in my town. According to automated recording at Pacific Power's power outage reporting number, the cause is a squirrel inside an electrical equipment at substation. Power was out from 11AM to 3PM. The cause was made available on recoding around 1PM and it took them another two hours to fix it.

How could one squirrel cause that much damage?

 

[RelaxTheMind]

a water droplet can fry my motherboard and if i wanted purchase a replacement and get up and running in about 2 hours.

Similar issue but smaller scale.

you have to be careful when turning regulated power back on. I've seen several blocks get fried because they turned power back on with too much juice. Each home requiring about $7k in damages dependent on what was damaged.

 

[compuwiz1]

I'd venture a guess, that squirrel will never do that again!

 

[KMurphy]

At higher voltage levels, one large power circuit breaker will ultimately feed sections of towns. If a squirrel bridges an insulator on a transformer or busbar at an outdoor substation, then the breaker will open and interrupt the fault. Most utilities have reclosers that close the breaker after a few seconds in case the fault self cleared. When a squirrel bridges an insulator, carbon deposits will foul the insulator requiring it to be cleaned or replaced. If a fuse blew, the fuse would have to be replaced. The through fault for the source transformer could have also made the transformer fail (they can only handle through fault current a few times). If the fault didn't clear in a few cycles, then busbar or air-insulated cables would have to be replaced as well.

 

[NeoPTLD]

Originally posted by: RelaxTheMind
a water droplet can fry my motherboard and if i wanted purchase a replacement and get up and running in about 2 hours.

Similar issue but smaller scale.

you have to be careful when turning regulated power back on. I've seen several blocks get fried because they turned power back on with too much juice. Each home requiring about $7k in damages dependent on what was damaged.

Substation is switches, transformers and capacitors, big passive components

Your motherboard is full of sensitive semiconductor components like VLSIs. Very different.

Originally posted by: KMurphy
At higher voltage levels, one large power circuit breaker will ultimately feed sections of towns. If a squirrel bridges an insulator on a transformer or busbar at an outdoor substation, then the breaker will open and interrupt the fault. Most utilities have reclosers that close the breaker after a few seconds in case the fault self cleared. When a squirrel bridges an insulator, carbon deposits will foul the insulator requiring it to be cleaned or replaced. If a fuse blew, the fuse would have to be replaced. The through fault for the source transformer could have also made the transformer fail (they can only handle through fault current a few times). If the fault didn't clear in a few cycles, then busbar or air-insulated cables would have to be replaced as well.

Aren't high voltage busbars spaced further than the length of the entire squirrel?

 

[KMurphy]

It depends on the voltage. Typically, 10KV - 35KV, insulators and spacing will not be sufficient to keep an animal from bridging the gap. 69KV and higher voltages usually have sufficient spacing and creepage distances.

If this was a 25KV fault, imagine 15,000A flowing for 10 cycles (1/6 of a second). That would be approximately 375MVA of fault energy or over 100MW (135,000HP) depending on the power factor of the fault for 1/6 of a second. It doesn't take long for a lot of damage to occur with the uncontrolled release of electrons.

 

[toolboxolio]

Nerd wars!!!

*waits to see who mis-regurgitates "google search" knowledge...


(copy and paste to avoid mistakes, nerds)

 

[adairusmc]

We had a badger (according to Verizon) chew through some armored direct burial cable, taking down a few thousand phone customers and kill a couple of DS3's we had running up to Enterprise, OR.

 

[KMurphy]

Idiot. Not everyone on this board is in IT :disgust:

EDIT - that is in response to toolboxolio's sense of inferiority and urge to lash out about his inability to understand what he just read.

 

[BrownTown]

Originally posted by: toolboxolio
Nerd wars!!!

*waits to see who mis-regurgitates "google search" knowledge...


(copy and paste to avoid mistakes, nerds)

Umm, you do realise like a third of this board is electrical engineers and not all of them work with computers. I sure as heck don't need to look up on google to know how a substation works, I spent the last two summers as an intern for people designing them, this isn't exactly difficult stuff to understand. There are insulators in substations to keep the different phases apart, and to keep each phase from ground, now it a retarded little squirel puts its stupid little feat on one side of an insulator and manages to reach close enough to ground or another phase than it will arc and blow the squirel to pieces. In alot of the lower power substations the fault protection is done with fuses, if that is the case whent he fuse blows some dude has to go out there and replace it. Even with breakers something can be damaged during the fault and not operate correctly, or the squirels body (whats left of it) might remain in place long enough that when the circuit breakers reclose it arcs again and then the breakers lock out until somebody goes and sets them back manually.

 

[amdskip]

I grew up next to the town's substation. Needless to say I've seen many a squirrel go up in flames. It scares the crap out of you when it happens living right next to the station.

 

[grrl]

The same thing happened at my university. About half the campus was without power for a day or so when a squirrel decided to 'bridge' a couple of wires.

 

[Boo Boo]

standing on 1 wire and tail brushes other wire, sniff sniff its steak

 

[WhoBeDaPlaya]

Originally posted by: BrownTownUmm, you do realise like a third of this board is electrical engineers

*Raises paw*

 

[chusteczka]

Originally posted by: KMurphy
At higher voltage levels, one large power circuit breaker will ultimately feed sections of towns. If a squirrel bridges an insulator on a transformer or busbar at an outdoor substation, then the breaker will open and interrupt the fault. Most utilities have reclosers that close the breaker after a few seconds in case the fault self cleared. When a squirrel bridges an insulator, carbon deposits will foul the insulator requiring it to be cleaned or replaced. If a fuse blew, the fuse would have to be replaced. The through fault for the source transformer could have also made the transformer fail (they can only handle through fault current a few times). If the fault didn't clear in a few cycles, then busbar or air-insulated cables would have to be replaced as well.

I am laughing at the comical thought of a squirrel bridging an insulator, getting zapped, and opening a breaker. Now that the squirrel feels safely in the clear thinking he is lucky to have survived that shock, the recloser automatically closes the breaker again just in case the problem has cleared itself, resulting in baked squirrel carbon bits for breakfast.

That routine would be perfect for the roadrunner and Wile E. Coyote.

 

[Jeff7]

Originally posted by: amdskip
I grew up next to the town's substation. Needless to say I've seen many a squirrel go up in flames. It scares the crap out of you when it happens living right next to the station.

Like a bug zapper killing the world's largest mosquito, eh?