Problems concerning pantograph collection of current during winter for high speed trains

Abstract: The idea of making this report was to try and shed light on the many problems of pantograph collection of current during winter time for high speed trains. The greatest difference between Sweden and other countries who already have built high speed rails is our yearly severe winter conditions. The problem about pantograph collection during winter is that the contact between the pantograph and the contact wire gets worse if ice isolates in between those two. That creates electric arcs that can harm both the pantograph and the overhead contact wire. For a high speed track the problems are expected to be even greater. It’s important that the Swedish Transport Administration, at an early stage, learns what causes the delays and the unwanted stops. My work started by doing a thorough literature study, where I tried to summon the overhead contact line theory from a winter perspective. After this a number of attempts have been made to illustrate different solutions on how to avoid that ice stays on the overhead contact line or the pantograph. In the first attempt I examined the thickness the ice would get on the contact wire if the air temperature suddenly fell from 0 C till  5 C and super cooled rain would fall for an entire 24-hour period. In my second attempt I tried the possibility to use a heated pantograph combined with an ice scraper. I used an American ice scraper as basic idea, but modified the contact strip part and made its shape cylindrical and hollow. The idea was that the scraper would reduce the ice on the wire and that the heated brass contact strip would melt the rest. In attempt three I looked into other materials that would be more suited for winter climate. As suspected the already existing materials, are not good enough and the futuristic ones are too expensive at the present time. Attempt number four was all about heating the contact wire with a magnetron that was going to be assembled on the pantograph. Unfortunately this result was not a success as it turned out that ice does not heat very well from microwaves. In the fifth attempt I focused on ice scrapers by studying tribology. Using an ice scraper may work, but probably best in combination with some of the other methods. Testing how this would be done in the best way will take some time. In the sixth attempt I looked into the possibility of heating the contact wire by adding extra current to the system. This is the way of handling the problem that I believe to be the most promising. In addition to these approaches, a simulation was made to show a phase change in the computer program Comsol.