Power outage - Transmission Tower Down

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#3252909 25-Jun-2024 10:42

raytaylor:
It would have been fascinating to watch the control rooms disconnect everything off the 110kv line so that Ngawha could start up using feed from Henderson and then bring the consumer loads back on

Yes, it's an interesting idea.
I wonder if there was already a set of procedures for this scenario, or if there were some very serious but quick engineering huddles to scope out a new set of procedures.
Either way, I'd bet there will be some careful risk analyses and plan developments going on at Transpower HQ this week and the next couple.

tweake

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#3252913 25-Jun-2024 10:46

Scott3:

My apologies to sir1963.

Quote from "Omexom NZ chief executive Mornez Green"

"The normal procedure is to remove the nuts on one leg at a time but three legs of the tower had the nuts removed"

https://www.nzherald.co.nz/nz/northland-power-cut-businesses-want-compensation-from-transpower/OMNTZTQEAJEC7CWTIM5T4ARFHU/#google_vignette

it was reported early on that it they where meant to do one leg at a time. however i saw the interview of the boss lady who mentioned it was meant to be one nut at a time.

tweake

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#3252917 25-Jun-2024 10:52

SomeoneSomewhere:

Generation not being able to black start is an issue that's been around for more than a century. We're unusually lucky in that most hydro plants need a backup diesel to operate control gates because the lake levels need managing even if you cannot generate, and hydro is about the easiest source to black-start, so most NZ plants can black start fairly easily, and if not can be quickly bootstrapped.

Start looking at coal, gas, nuclear, and you can need almost as much power as the whole of Northland pulls just to start the plant up.

It wasn't an issue for long; it sounds like minutes or tens of minutes to get the right lines energised from the remaining 110kV circuit.

Meridian's Ruakākā battery farm will provide more black-start capability in the area.

it will be interesting to see if they do have black start ability at ruakaka. as we get more and more solar etc, we could end up with issues like in usa where they had large blackouts even tho the solar had the capacity to keep going.

eracode

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#3252920 25-Jun-2024 10:56

SomeoneSomewhere:

62 billion, not trillion... they also own one part of the group that built Transmission Gully.

Correct - I got thrown by the European comma in place of our decimal point. Their EUR61,675b v our EUR61.675b.

Sometimes I just sit and think. Other times I just sit.

larknz

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#3252951 25-Jun-2024 11:37

eracode:

Scott3:

[snip]

Quote from "Omexom NZ chief executive Mornez Green"

TL;DR: Omexom is not some fly-by-night local contractor - it’s a well-established multinational operator who are unlikely to take kindly to what happened here.

FWIW a search of the Companies Office website shows no entry for Omexom. However a search for Mornez Green shows connections with Electrix Limited and VINCI Energies NZ Limited.

A google search for Omexom NZ shows that Elextrix Linited is “trading as Omexom New Zealand”.

ONZ has been around for a long time:

“Electrix, trading as Omexom New Zealand, is a leading provider of engineering, construction and maintenance services to asset owners in the utility, industrial, commercial, resources, and infrastructure sectors. We have been in business in New Zealand since 1955 and became part of the multinational VINCI Group in 2014.”

Omexom global website.

Wikipedia page on VINCI SA.

Fun fact: Internationally VINCI has an annual turnover of EUR62 trillion.

Electrix is well established as a contractor to Transpower.

Bung

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#3252955 25-Jun-2024 11:47

SomeoneSomewhere:
62 billion, not trillion... they also own one part of the group that built Transmission Gully.

So there's an outside chance the tower painters could end up buried somewhere under the Otaki to north of Levin expressway extension?

SomeoneSomewhere

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#3252956 25-Jun-2024 11:50

raytaylor:

I dont think there could be that many different models of pylon in NZ.

If I was ordering 200 pylons for a new transmission line, I would be adding a few extra kitsets to the order as spares so we can keep them at a few yards for emergency use and replace as needed.



I definitley dont like those land of giant pylons. I have always felt our existing ones look quite nice as they are.

It's a combination/permutation problem.

There are probably at least a dozen different general tower designs. Single/double circuits of each 66, 110, 220 and double circuit 400kV, plus HVDC with and without electrode cables, and the standalone electrode cable towers.

There are at least two different types of double-circuit 220kV towers (where the central crossarms are wider as on CPK-WIL-B, and where they are all the same like the tower that fell), and of HVDC towers. A small number of triple-circuit 110kV towers in Wellington, though I think they have special plans in place for those because they are very critical. I know the insulator strings get longer in coastal areas, particularly on the HVDC; I am not sure whether this necessitates another tower type for more clearance.

Each type of tower is available in both a 'normal'/'suspension' form and a 'strain/'dead-end'/'tension' form, which is significantly stronger and built to withstand tension on one side with no lines on the other.

Each tower then comes in a bunch of height variants - a common upper part, then a variety of different leg extensions with different footprints depending on required clearance.

And finally, there's different variants where the line turns a corner (of varying sharpness) at the tower.

Pulling the line up and sideways (each circuit to opposite sides if necessary) with an adjustable/over-height guyed tower is much easier and gets the line away from the failed tower, so that you can safely remove the wrecked tower and do any foundation repair work or slope stabilisation. It's possible that the footing of the one leg that was left bolted down is quite torn up.

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neb

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#3253094 25-Jun-2024 15:43

PolicyGuy: I wonder if there was already a set of procedures for this scenario, or if there were some very serious but quick engineering huddles to scope out a new set of procedures.

It'll have been something like this. And just like that one, it's probably going to end up in engineering failure tutorials and videos for decades to come.

Edited to add: Link to different coverage that focuses more on the engineering details.

wellygary

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#3253097 25-Jun-2024 15:55

neb:

It'll have been something like this. And just like that one, it's probably going to end up in engineering failure tutorials and videos for decades to come.

Or, As this country is unfortunately famous for, a notable politician will bang out a headline of
"because it lacked about $20 worth of bolts to hold it together"

Although thankfully this time there were no lives lost.

tweake

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#3253106 25-Jun-2024 16:25

neb:

PolicyGuy: I wonder if there was already a set of procedures for this scenario, or if there were some very serious but quick engineering huddles to scope out a new set of procedures.

It'll have been something like this. And just like that one, it's probably going to end up in engineering failure tutorials and videos for decades to come.

Edited to add: Link to different coverage that focuses more on the engineering details.

its failure is probably very similar to the Kelowna crane collapse. i don't think there is an official report thats been released yet, but the money is on they removed the bolts holding it together in advance of it being disassembled (if i recall correctly). doing the job out of sequence in an effort to speed things up.

ezbee

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#3253107 25-Jun-2024 16:30

You can simultaneously have too many 'nuts' and not enough 'nuts' at the same time.

Bolts can be trouble as well.
Using computer or manual to check size is too slow.
Pressure to get work done quickly, people develop little shortcuts, becomes normalized.

The Captain That Got Stuck Outside Of The Plane! | Blow Out | FULL EPISODE | Mayday: Air Disaster
https://www.youtube.com/watch?v=7xfaDr0nhoQ

It kinda creeps up on you it works once, then again, and now its normal.

tweake

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#3253114 25-Jun-2024 17:25

ezbee:

You can simultaneously have too many 'nuts' and not enough 'nuts' at the same time.

Bolts can be trouble as well.
Using computer or manual to check size is too slow.
Pressure to get work done quickly, people develop little shortcuts, becomes normalized.

The Captain That Got Stuck Outside Of The Plane! | Blow Out | FULL EPISODE | Mayday: Air Disaster
https://www.youtube.com/watch?v=7xfaDr0nhoQ

It kinda creeps up on you it works once, then again, and now its normal.

one of my favorite shows. didn't realize they had a utube channel.

you would naturally assume that the bolts you remove are the correct ones and you replace them like for like. but part of the procedure is done to make sure someone else didn't screw up.

the episode about the plane that lost the leading edge of one of the wings, which caused it to nose dive and crash, is a good human factors study. an engineer helped the other staff by removing bolts on the other wing they where due to work on next. then he left for the day. but the staff ran out of time and didn't start on that other wing, so they never looked at it to see it was already unbolted. so the plane got accidently send out with the bolts taken out on one side.

tweake

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#3253120 25-Jun-2024 17:34

kinda reminds me of getting growled out for leaving farm gates open. we have the farmers rule of "leave it as you find it", so if the gates open leave it open, if its closed make sure its closed after you go through.

so we get to the paddock, gates open, we go through. however the (former) boss was already in the paddock and the genius was being "helpful" (ie lazy) by leaving the gates open for us, expecting us to close the gates for him. which we didn't do because they where open before we got there.

neb

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#3253228 25-Jun-2024 22:40

neb: Such a pity John Clarke isn't around any more, he could reprise his front fell off sketch into a tower fell over sketch: "That's not very typical, I'd like to make that point. There are a lot of these transmission towers all over the world and very seldom does anything like this happen".

I wonder if someone at the BFD reads GZ?

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#3253338 26-Jun-2024 09:38

spooky or what!

They should have used a photo of the actual pylon though.

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