Since my post yesterday about the Heathrow fire "did numbers", as the influencers say, I just wanted to use the opportunity to say:
The power's back on now, and that's no doubt thanks to the hard work and dedication of some hugely skilled workers at National Grid. I hope everyone can spare a thought for them, as I don't doubt this has been a very rough 24 hours.
6/6
Which brings me to the point of this little spiel.
The UK electrical transmission and distribution networks are in a shocking (pun intended!) state.
Especially the distribution network.
The UK electrical grid is a miracle of engineering. For the last few decades it's been held together by ingenuity, tenacity and luck, while the disgusting leeches we've sold it to suck every last drop of money they can out of it.
And you know how you can make more money? cut back on maintenance. Cut back on asset replacements. Cut back on staff. Sweat the assets.
I'm not saying lack of maintenance caused this. How could we know? But as someone who works on the grid, I'm not surprised by it, put it that way.
Just like the rest of this rapidly declining country, the grid is run for the sole purpose of corporate cash extraction. And it makes me sick.
5/6
What caused it?
Who knows?
If I were placing a bet on why a transformer failed, and with no other information, I would always put my money on a tapchanger fault.
A tapchanger is a device that lets you change the output voltage of a transformer, and it's one of the few mechanical parts subject to wear and tear they have. They need regular maintenance.
I've seen people speculating about sabotage. Now as someone in the industry, I am acutely aware how easy it would be to cripple the grid by hitting a few vulnerable locations, but honestly transformers fail all the time. This one just happened to be in a high profile spot.
4/6
I would expect that they will try and restore power through switching operations well before that.
What that entails in basic terms is you connect the load that was served by this transformer to a different transformer. The UK network is built with redundant inter-connectivity for this very reason.
The issue with doing this of course is that you are then potentially overloading the transformer you switch to, so this can only be a short term solution.
3/6
Recovery efforts then.
Not that long ago, I was part of a team that responded to exactly this sort of catastrophe.
Our record for replacing a failed transformer was four days. That was remove the old one, install and commission the new one. And that was a 33kV, so quite a lot smaller.
When there's been a fire, you can't just start working. The site will have to be made safe, that takes time. You're going to need cranes, haulage, oil tankers, labour. It's not a trivial task.
You can't move a transformer in one piece. The cooler banks and conservator, the A-frame for the radiators, the pipe work (and there can be a lot of pipework) all has to be dismantled, and then the new one built on site.
2/6
Substations, and the transformers inside them, are basically the links in the chain the make up the UK grid.
Power is generated at power stations, and moved around the country at extremely high voltage, 400,000 volts (400kV).
This is then "stepped down" at a substation to 132kV, then stepped down again to 33kV at the next sub, then again to 11kV at the next, and finally to 410/230V that we all rely on when we stick a plug in the wall.
(Yes, I'm aware of all the other voltages. There's a character limit)
When a transformer fails, it takes out everything below it in the chain. And obviously, the further up the chain the failure, the more stuff downstream is affected.
Few thoughts on the substation fire at Heathrow. 1/6
From the limited information available it looks like fault has caused one of the transfomers serving the site to burst into flames.
Apparently National Grid (the transmission side, not the DNO) are involved, so that suggests we're talking about a bigger transformer, probably a 132 kV unit or bigger.
For the un-initiated, you have to understand that when I say "Transformer" I'm talking about something weighing north (possibly well north) of 40,000 kg , full of thousands of litres of highly flammable oil.
If you've ever seen the aftermath of a large transformer going up, you know how serious this is.
