11 kV lines down at 753 Te Atatu rd, Te Atatu North during storm on 24.01.2006 around 16.00 hrs, 4 km from Te Atatu sub. on Harbour view feeder. Earth fault protection failed hence the damage. 185mm² Al cock roach till 1 span before ABS 638 then Cu 16mm² for the next 1.5 km's. This is a non fused section on a 400 Amp feeder at the end of a long suburban feeder. By this ABS 4 spans of 11 kV were down and another 4 separate spans at the end of this line. Amazingly no damage was done to the 230 / 400 volts services which I had inspected by a contract inspector during the repairs. Power was restored at around 01.30 hrs. 25 transformers were off and about 1500 customers affected.
ABS 638 minus its 11 kV wires:
Melted cables, the storm hasn't even started to full power yet:
Melted 16mm² Cu O/H cable:
Burn marks in the grass:
[This message has been edited by Trumpy (edited 02-09-2006).]
Wowzers this stuff is amazing. I live in a neighborhood with 12KV OH lines, old ones too. You know, the kind that fall occasionally in wind storms. Luckily none of the 12KV runs thru my yard, but one fell in my across-the-street neighbor's back yard a few years ago. Almost landed in his pool. It relayed off and on and off again before locking out, lots of arc marks on and around the house.
There are 10 types of people. Those who know binary, and those who don't.
Re: 11kV lines down#122939 02/10/0612:48 AM02/10/0612:48 AM
Wow! It really makes you take a step back and think about the amount of energy that can be delivered over a couple of measley conductors.. In my city the O/H ranges anywhere from 4KV all the way up to 27.6 KV.. We once had a 4KV circuit knocked down just behind my house but it didn't trip the substation breaker and did not arc or spark at all but was still hot!.. Someone actually tried to move this hot wire off their driveway with a dry pice of wood just so they could get their car out... It didn't work as they recieved a good shock but it did not harm them thank God! Some people just do not understand!
I once worked on a house where a 12KV primary broke loose and landed on the home's service drop.. Crazy things happened there! The 86 year old homeowner told me she was just sitting in her rocking chair and it sounded like someone fired a cannon in her backyard! GFI's with the faces blown off, the panel had a hole blown through the back (FPE), but strangely, some appliances survived.. others just made blue smoke when we tried plugging them into a generator.
Another time I happen to be around when 2- 33KV lines lost to gravity north of downtown Los Angeles in a storm... The arc-blast was enormous enough that the streets dept had to spot repair where the lines had fallen on the street (asphalt), where they had hit the sidewalk (concrete) it looked like it turned it to glass!