\section*{Acknowledgments}
This work was completed as part of the research project VulPro (``Risk and Vulnerability Prognosis for Power System Development and Asset Management''). The project is co-funded by the Research Council of Norway under Grant number 308781 and in part by Statnett (the Norwegian TSO), Landsnet (the Icelandic TSO) and the Norwegian Water Resources and Energy Directorate. The authors would also like to thank Landsnet for providing condition and outage data for high-voltage circuit breakers.