The article presents a review of domestic and foreign sources relating to problems of improving thermophysical parameters of polymer materials, impregnating varnishes, electrical insulating tapes and composite materials used as electrical insulation in high-voltage equipment, while retaining their electrophysical, mechanical and technological properties. The author reviewed publications for the past 20 years published by the authors from Russia, USA, Germany, France, Great Britain, Japan. The study used the Russian Patent Office database, Orbit database, European Patent Office database, Eurasian Patent Office, Patent Cooperation Treaty and the Internet. In the course of the engineering and technical analysis, the known data published in the open scientific and technical press were summarized, the level of technical development was assessed and highlighted. The results include a comparative analysis of the characteristics of polymer materials filled with highly heat-conducting dielectric particles and a list of the main trends in the development of the research object.