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Joined: Dec 2005
Posts: 866
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RODALCO Offline OP
Member
It happened again, power was out in a large part of Auckland and up North towards Whangarei and Cape Reinga.

A 220 kV line going North was tripped in Onehunga while a large shipping container was within the safe M.A.D. of one of the main 220 kV lines.
A flashover occured to the container stacker.
The driver was ok but shaken.

The other main 220 kV circuit going North was out for maintanance, the trip of the other line caused a domino effect and power went off for about 1 hour.

It is being addressed that the system in Auckland needs a back up double circuit line going north which will take an other 5 years to be in place.

My question is why have a shipping container stacking yard within the easement of overhead 220 kV lines ?

http://tvnz.co.nz/national-news/major-power-cut-hits-auckland-northland-3101635

Just a new topic to get some conversation going.

Kind regards, Raymond


The product of rotation, excitation and flux produces electricty.
Joined: Jul 2002
Posts: 8,407
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Woah!,
Our lights seemed a lot brighter down here in the South Island today. grin
We even shut 3 generation stations down and had Benmore idling. yay

Could this be because all the Latte machines in Auckland had no power?

Even so Ray, I think it really comes down to the people that voted and protested against the 400kV upgrade.
If that had have gone ahead, the lines would have been a lot higher.

You reap what you sow.
whistle

Joined: Dec 2005
Posts: 866
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R
RODALCO Offline OP
Member
Overloaded Auckland lines sag a lot and the clearances are less, hence the container stacker got away with it under normal conditions but not while one circuit was out.

The 400 kV line may be built now a bit faster although this incident happened between Otahuhu and Henderson, and this power black out would also have happened if the 400 kV line was in place.

Aucklanders and myself love our latté and capuchinno and our coffee machines were off indeed :-)

Lucky that the South Island generation didn't trip off on overfrequency because of the sudden load loss on the network.
Those hard working S.I. generators probably appreciate a little break in their arduous duties for the power hungry Auckland city dwellers.

I wonder if any HV powerlines or the DC lines were swaying because of the instant drop of a large load.


The product of rotation, excitation and flux produces electricty.
Joined: Jul 2002
Posts: 8,407
Likes: 2
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Ray,
I hope you realise that most of what I posted above was in sarcasm. cheers

Personally,
I hope that most of the affected loads have now been re-energised, although with my experience of re-connections, that would not have been an easy task.


Joined: Dec 2005
Posts: 866
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RODALCO Offline OP
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No worries mate, I knew that coffee :-) :-) stir, but it is great for a chat and laugh.

The re-energising took a couple of hours as loads were switched on in sequence to avoid further problems.

I was working at Penrose switchyard which was not affected and is fed from another double circuit 220 kV line.
Installing a 250 MVA interconnector transformer 220/110kV to secure the CBD supply. I will post some piccies and will start a new thread about that job.


The product of rotation, excitation and flux produces electricty.
Joined: Feb 2003
Posts: 367
M
Member
Ray, does your utility do a nip and tuck on existing transmission lines to improve clearences?

The utility that services my part of Canada is doing that on up 20 to 90 year old HV transmission lines to improve clearences brought on by the extra loads that were not there when the lines were built.

Apparently if they do it correctly they can increase transmission voltages by 100% and still have proper ground clearence.

Joined: Dec 2005
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RODALCO Offline OP
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They do.

On the 220 kV lines around Auckland they have replaced the hanging insulators on certain pole structures.
Instead of the hanging strings there is a triangular arrangement with resin insulators and increased the clearances from the conductors by several meters.

I will take a photo in my travels and post it in the photo gallery.

This issue is still under investigation but it appears that this container firm has had a line clearance warning before but that didn't cause an incident.


The product of rotation, excitation and flux produces electricty.
Joined: Jul 2004
Posts: 783
L
Member
Quote
a large shipping container was within the safe M.A.D. of one of the main 220 kV lines.


What is a M.A.D ?

Joined: May 2005
Posts: 984
G
Member
Minimum Approach Distance??


Ghost307
Joined: Aug 2006
Posts: 27
O
Member
Always good when the power goes out for a while.
Give us a chance to get the really important things done that don't need power.

OA

Last edited by OldAppy; 11/12/09 02:04 AM.
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