Bill Black, by email asked:
How can we protect power grids from solar storms?
We put this question to Lucie Green, from University College London (UCL)...
Lucie - Well, we can't stop its impact with the Earth. That's absolutely certain. So, when it arrives, what happens is it encounters the Earth’s magnetic field.
So, these coronal mass ejections are magnetic bubbles themselves in a sense and then they interact with the Earth’s magnetic field. If you change the Earth’s magnetic field, you can start to create electric currents.
But the national grids, they are interested in the very large events. There's day to day space weather as I said was sitting in a dynamic and variable atmosphere of the sun.
But national grid in this country are really interested in the big one that could cause a lot of currents, set up a load of currents that would then affect their electricity networks.
So, they do take into account what the sun does. They are watching it all the time.
What they can do is make sure that there are people at the relevant substations that need to be monitored.
But they do have ways of bringing up power lines if necessary and monitoring the systems.
But all of these take time, and this is why we need the forecast, the warning of what's going to arrive at us and whether it’s going to have a strong impact.
Space weather forecasts will start from the spring of 2014 and are designed to give early warning to private companies and public utilities with critical equipment that is vulnerable to electrical malfunction during a large solar storm . Smith Henry, Thu, 23rd Jan 2014
Space weather induces very low frequency currents in the Earth (almost DC).
One nice thing about solar flares is that the visible portion travels to Earth in a matter of minutes. The ion portion which causes the electromagnetic interactions travels over the course of a few days.
The damage to transforms arises from the direct current induced by the Solar storm saturating the core and allowing excess current in from the grid.
The crash bang modern films always show the small cylindrical transformers mounted on poles that are such a part of the American scene exploding, what is the typical KVA rating of these transformers ?, to an European the configuration of the system seems rather strange with the centre tap of one of the 220v delta three phase windings grounded to provide two 110v supplies to domestic users.
I'm seeing ratings of the utility transformers between 5 & 1000 KVA or so.
When I was fixing TV,s for living I came across one case where the neutral line had failed on the three phase star connected 415/240v domestic system so that the voltages varied wildly as people switched different loads on, I broke the rules and connected the neutral to ground to avoid the TV getting destroyed. syhprum, Sat, 25th Jan 2014