History of Science and Engineering Annotation << Back Experience in development and exploration of high-voltage equipment for dc transmission L.V. Travin V.V. Khudyakov The paper presents the history of the creation and development of high-voltage power electronics and conversion technology as well as the development of the equipment for high-voltage direct current (HVDC) power transmission at the All-Russian Electrotechnical Institute (Russian abbreviation – VEI). The paper covers the period of 1921–1970 and contains the memoirs of some VEI engineers directly taken part in theoretical and experimental studies of normal, transient and fault operating modes, in the development of high-voltage converter equipment and in putting the first HVDC power transmissions (Kashira–Moscow and Volgograd–Donbass) in operation. Key words: High-voltage power electronics; converter technology; simulator studies; mercury valves; HVDC power transmission; putting into operation. Pp. 31-41