In the power network, electrical equipment condition is coordinated according to the scheduled inspections of various parameters. Online equipment monitoring systems can be applied for the prevention of equipment failure. From time to time electrical equipment insulation is exposed by a short duration disturbances, which can be caused by switching of transmission lines, single phase ground fault in the insulated neutral network, or external disturbances, which can be caused by the lightning strike to the structures of overhead transmission line or close to it. These disturbances cause the appearance of overvoltage of various duration and levels in the power network. In case there are defects in insulation, the exposure of overvoltage increases these defects. Moreover, overvoltage affects partial discharge characteristics and increases insulation ageing processes. This paper analyzes the partial discharge characteristics when short duration overvoltage occurs. Models with artificial defect are selected for investigation. Partial discharge characteristics in insulation with the artificial defect, during transient overvoltage analysis, are provided in this paper. The experiments related to short duration overvoltage, different size of defects, and observation of variation of partial discharge characteristics are carried out. In addition, the dependence of partial discharge characteristics on operating overvoltage pulse characteristics was determined.