Method for characterizing of insulation level of e.g. cellulose oil-insulated power transformer, involves switching resistor capacitor parallel elements from three points of curve of measured return voltage curves of operating unit

摘要

The method involves switching resistor capacitor parallel elements from three points of curve of measured return voltage curves of an electro technical operating unit under assumption of characteristics of the return voltage curves according to a maxwell model, and calculating time constant of the elements. The time constant is used as a diagnostic criterion with time as implicit parameter. Influence of internal resistance of a voltage measuring device is corrected, and the return voltage curves are interpreted by the characteristics of the return voltage curves.