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Joined: Oct 2004
Posts: 806
mxslick Offline OP
Member
Hi everyone, just found THIS LINK of what has to be the most incredible example of how bad things can get when the power distribution system's protective relay scheme fails to do it's job. The events starting around 3:50 are especially dramatic.

The comments provide some interesting details..now imagine this nightmare going on FOR HOURS in your neighborhood!!

Thankfully, it seems that modern protective relay setups (the video is from 1988) are more reliable.

Even so, this situation made me wonder..even though the relay system had failed, and admittedly it would be very risky, but wasn't there any way a line crew could have manually cut the power using cutters or a thing I've heard of called a "loadbuster'? It would seem to have lessened the overall damage to the homes and distribution system.

Very sobering.

Joined: Mar 2006
Posts: 52
T
Member
Makes me happy that all the lines are underground in my town!

Joined: Aug 2001
Posts: 7,520
P
Member
Boy, that's some burnout. Around 3:55 is that arcing we're seeing on the service drop to the house? Looks like the HV might have shorted across to it.


Joined: Oct 2002
Posts: 482
Z
Member
The sound of that arc buzz always gives me the creeps. No sound like that in the world.

Joined: Jul 2004
Posts: 9,669
Likes: 6
G
Member
Why would it take the utility so long to shut down that area of the grid? It would seem that they could knock it down, cut the bad lines out and reenergize it.
Seeing that soffit go up does remind us why we want short service conductors that are not wrapping around the house


Greg Fretwell
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
It seemed to jumping around on AL siding or a gutter looking for return pathes though whatever it could find that was even remotely conductive in the house.

Could've been a step voltage hazard for those fire fighters walking around as well.

Reminds me that I have an 11KV line in my backyard and a nieghbors tree that needs a trim/lopping....


Mark Heller
"Well - I oughta....." -Jackie Gleason
Joined: Apr 2004
Posts: 811
Member
Originally Posted by e57
Reminds me that I have an 11KV line in my backyard and a nieghbors tree that needs a trim/lopping....


Reminds me of the 7.4KV (or whatever voltage Peco uses in Levittown) line in my backyard, and our huge Oak tree growing right into the pole transformer feeding onhe whole block...

(That of course my parents refuse to have cut since they think "it'll take care of itself.") shocked

Ian A.


Is there anyone on board who knows how to fly a plane?
Joined: Oct 2004
Posts: 806
mxslick Offline OP
Member
Originally Posted by Theelectrikid

<snip>
Reminds me of the 7.4KV (or whatever voltage Peco uses in Levittown) line in my backyard, and our huge Oak tree growing right into the pole transformer feeding onhe whole block...

(That of course my parents refuse to have cut since they think "it'll take care of itself.") shocked

Ian A.


Ian, just show this video to your parents and ask them if that is what they have in mind. smirk


Stupid should be painful.
Joined: Oct 2004
Posts: 806
mxslick Offline OP
Member
Originally Posted by Zapped
The sound of that arc buzz always gives me the creeps. No sound like that in the world.


I agree..I get nightmares from that sound...here in So Cal, the earthquakes don't bother me, it's the buzzing from all the O/H lines arcing that scares me.

And I 've been too close to too many arc faults in my lifetime to ever not be scared by it.


Stupid should be painful.
Joined: Oct 2004
Posts: 806
mxslick Offline OP
Member
Originally Posted by pauluk
Boy, that's some burnout. Around 3:55 is that arcing we're seeing on the service drop to the house? Looks like the HV might have shorted across to it.



Paul, I think from the comments on the video site that the service drop burned down because the transformer(s) on that feeder failed from the stress, letting full primary voltage get through to the secondaries.

If you listen closely before and after that spot, you can hear the transformer's(?) buzzing changing pitch during that timeframe.

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