Didcot power station 33KV incident 18/08/19

UKMeterman · Aug 18, 2019

Didcot power station cooling towers were demolished today,
in the process there was damage to a 33KV substation. The strange thing is that there was signifcant flashover on the 33KV network causing alleged damage and injury to the public. Some videos here

https://twitter.com/x/status/1163141363053056006

https://twitter.com/x/status/1163142579250245632

https://twitter.com/x/status/1163140628286443520

What do people think was the sequence of events?

rapparee · Aug 18, 2019

I think it was a rough bit of work.

The Risk Assessment should have checked out cables in the vicinity of the falling towers.

In one video you can see the towers hitting the cables, they were saying about and touching each other.

MJPD29 · Aug 18, 2019

rapparee said:
I think it was a rough bit of work.

The Risk Assessment should have checked out cables in the vicinity of the falling towers.

In one video you can see the towers hitting the cables, they were saying about and touching each other.

sounds like drunk students on a saturday night also

Deleted member 105166 · Aug 18, 2019

I read elsewhere on Twitter that a number of drones were filming the demolition and one was seen to strike overhead cables

UKMeterman · Aug 18, 2019

No,
A metal mat was blown off the coolingtower and landed in the 33KV substation compound. I do wonder if it caused a an over voltage on the 33KV network, I wonder if there was a 132KV 33KV power cross

Megawatt · Aug 19, 2019

UKMeterman said:
Didcot power station cooling towers were demolished today,
in the process there was damage to a 33KV substation. The strange thing is that there was signifcant flashover on the 33KV network causing alleged damage and injury to the public. Some videos here

https://twitter.com/x/status/1163141363053056006

https://twitter.com/x/status/1163142579250245632

https://twitter.com/x/status/1163140628286443520

What do people think was the sequence of events?

Do y’all think that dust from the cooling towers was conductive with carbon possibly shorted out the 33k power lines

Edtwozeronine · Aug 19, 2019

The 3rd twitter link seems to show it best but it also looks like after effects was used to make that blue alien-looking flash over.

marconi · Aug 19, 2019

The swaying HV lines in one clip is caused by the electromagnetic forces between them due to the fault currents flowing in them - see Ampere's Law and Lorentz forces. Perhaps the amplitude of these sways was such the lines touched causing the shower of sparks over any nearby onlookers.

[ElectriciansForums.net] Didcot power station 33KV incident 18/08/19

marconi · Aug 19, 2019

So, for a pair of parallel conductors, if the fault current was 10kA = I1 = I2 = then force per metre of line when the lines are a metre apart is:

1.25 x 10exp-6 x 10 x 1000 x 10 x 1000/(2pi x 1) =

approximately

1.25/6 x 10exp-6 x 10exp8 = 0.2 x 10exp2 = 0.20 x 100 = 20N/m

mu is the permeability of free space or magnetic constant and is - 1.25663706 × 10-6 m kg s-2 A-2

So for a 50m span total force is 50 x 20 = 1000Newtons.

As the force pulls the conductors together it increases - F is inversely related to r - so towards mid span where the conductors are freer to sway more, the forces will be much higher. On top of this, the impulse nature of this force will set up transverse vibrations of the conductors.

James · Aug 19, 2019

Radio 2 are discussing this right now

Lucien Nunes · Aug 19, 2019

1000Newtons.

Or 225 lbs force for the physics luddites on here and those who refuse to use metric at any cost. Either way it's a fair old pull. The operating voltage is immaterial here, the same force per unit length would be experienced by a pair of meter tails for example.

Pete999 · Aug 19, 2019

marconi said:
The swaying HV lines in one clip is caused by the electromagnetic forces between them due to the fault currents flowing in them - see Ampere's Law and Lorentz forces. Perhaps the amplitude of these sways was such the lines touched causing the shower of sparks over any nearby onlookers.

View attachment 51446

marconi said:
So, for a pair of parallel conductors, if the fault current was 10kA = I1 = I2 = then force per metre of line when the lines are a metre apart is:

1.25 x 10exp-6 x 10 x 1000 x 10 x 1000/(2pi x 1) =

approximately

1.25/6 x 10exp-6 x 10exp8 = 0.2 x 10exp2 = 0.20 x 100 = 20N/m

mu is the permeability of free space or magnetic constant and is - 1.25663706 × 10-6 m kg s-2 A-2

So for a 50m span total force is 50 x 20 = 1000Newtons.

As the force pulls the conductors together it increases - F is inversely related to r - so towards mid span where the conductors are freer to sway more, the forces will be much higher. On top of this, the impulse nature of this force will set up transverse vibrations of the conductors.

Is it me or am I looking at the wrong picture but those three cables./wires, that are swaying, look suspiciously like stay wires, judging by the protective sleeves on the last few meters, mind you I do wear Specs so I could be hopelessly up the wrong tree without a branch, what do you think,? good explanation by the way nice post.

marconi · Aug 19, 2019

I looked at Rachel Barbaresi's clip in #1 - with a bit of close observation one can see the conductors stationary and then vibrating. Click on enlarge bottom right before play.

snowhead · Aug 19, 2019

Whatever the cause it doesn't look good for the Didcot project.
The previous incident caused the death of 4 workers.

HSE will need a permanent office there if this continues.

Pete999 · Aug 19, 2019

marconi said:
I looked at Rachel Barbaresi's clip in #1 - with a bit of close observation one can see the conductors stationary and then vibrating. Click on enlarge bottom right before play.

Will do 5 blinking words

Didcot power station 33KV incident 18/08/19

UKMeterman

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rapparee

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MJPD29

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Deleted member 105166

UKMeterman

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Megawatt

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Edtwozeronine

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marconi

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marconi

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James

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Lucien Nunes

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Pete999

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marconi

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snowhead

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Pete999

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