See Russian wiki page on 6 kV:Электроподвижной состав на напряжение 6000 В July 2, 2026 by jlamprecht https://ru.wikipedia.org/wiki/%D0%AD%D0%BB%D0%B5%D0%BA%D1%82%D1%80%D0%BE%D0%BF%D0%BE%D0%B4%D0%B2%D0%B8%D0%B6%D0%BD%D0%BE%D0%B9_%D1%81%D0%BE%D1%81%D1%82%D0%B0%D0%B2_%D0%BD%D0%B0_%D0%BD%D0%B0%D0%BF%D1%80%D1%8F%D0%B6%D0%B5%D0%BD%D0%B8%D0%B5_6000_%D0%92
