Test of Durability of Epoxy Resin Insulation of Converter Valve Saturable Reactor Under Pulsed Voltage and Pulsed Heat

Saturable reactor used in UHVDC converter valve withstands periodic pulsed power loss, which will generate periodic pulsed electrical stress and pulsed thermal stress inside the epoxy resin insulation. The aging and life characteristics of epoxy resin insulation material under this condition are not clear yet. The operating conditions and insulation problems of saturable reactor are described in this article. Aiming at the electric and thermal aging factors, the pulsed electric aging experiment platform and the pulsed thermal effect experimental platform were designed respectively, and preliminary study on the life and aging characteristics of epoxy resin specimens were carried out. The results show that under the repeated action of the pulsed voltage, the lifetime of epoxy resin decreases with the increase of the voltage amplitude according to the inverse power law. Through magnified observation, we found that as the aging time increases, the surface roughness of the epoxy resin sample increases, and lots of pits appeared on surface. The repeated impact of pulsed heat has little effect on the surface electrical characteristics of the epoxy resin sample, but as the number of thermal shock increases, the electrical strength of the epoxy resin surface decreases.