The insulation recovery time after arc interruption must be known to select the adequate reclosing dead time of rapid auto-reclosing on transmission lines. In order to study insulation recovery characteristics after arc interruption on UHV (1000 kV class) transmission lines, many tests were carried out using the high power test facilities of CRIEPI. In this paper the authors describe the experimental results of these tests of insulation recovery characteristics after arc interruption of UHV transmission lines, and some factors influencing these characteristics. >