I. Introduction
One of the technological trends is towards more and all-electric apparatuses and more electrification, for example, all-electric transportation. This will lead to higher electrical demand. Either higher currents or higher voltages can provide increases in electrical power demand. Due to weight and voltage drop, a raise in the current is not preferred, so higher voltages are being considered. Another trend is to reduce the size and weight of apparatuses, leading to high power density designs. Combining two trends results in high voltage, high power density concept. Note that a high voltage and high density combination produces a high electric field. And high power and high density are translated to high temperatures. Here the Achilles heel is electrical insulation, where two mentioned impacts, higher electric stress and higher temperatures, provide a severe working condition for any insulation system. Therefore a significant challenge for most present-day technologies and the technologies of the future is the compact and reliable design of insulation systems for their electrical components.