Abstract: A method and system for identifying, the cause of a partial discharge occurring in an electric system, which method increases measuring a variable of the electric system, such as voltage or current, to which partial discharges occurring in the electric system cause pulses, separating the pulses caused by partial discharges, i.e. partial discharge pulses, and occurring in the measured variable, defining and storing pulse parameters depicting the partial discharge pulses, or information from which the pulse parameters can be derived, defining (301) one or more pulse group graphs by means of the pulse parameters after at least a predefined number of partial discharge pulses, i.e.