Something To Bragg About!
A few days ago, someone asked me about the overhead wires of a railway and the pantographs, that pick up the 25,000 Volts AC current.
I can’t remember what their question was, but I said it is a difficult problem, as a train like a Virgin Class 390 Pendelino might be travelling at 125 mph in bad weather, so maintaining contact with a constant pressure between the pantograph and the overhead wire isn’t easy.
I was reading something else and found this article on the Rail Engineer web site. Research has been going on at the City University to develop a sensor that monitors the forces at the pantograph head. As you can imagine it is a particularly harsh environment and the engineers have bean using a technology called a Fibre Bragg Grating (FBG) developed in the 1990s, based on the work by the Nobel Prize-winning scientists William Lawrence Bragg and his father; William Henry Bragg.
I won’t paraphrase the article, but it is a must read. Where it will all lead to I don’t know, but I will repeat this last paragraph.
In the long term, the FBG sensor system offers the ability to detect contact forces from the entire service fleet if combined with GPS and suitable telemetry. This offers the potential of continuous real-time monitoring of the entire overhead line network. Then the Braggs’ work on X-ray diffraction of crystals a hundred years ago could well have made overhead line dewirements also a thing of the past.
Just imagine what it would mean to the operators of our increasingly electrified rail network, if delays caused by trains bringing down the overhead wires were to be reduced.
I’ve met people at Cambridge University for whom William Lawrence Bragg was their tutor and they have described him as a quiet man, who was superb in getting brilliant work out of the students, he tutored.
This tale illustrates why we must do more and more research and often that the solution to a difficult problem is unexpected, but brilliant.
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