Investigation of complex, in-homogenous insulation system with multiple time constant by recovery voltage measurement (RVM)

The most important element in the transmission network is the power transformer with oil paper immersed winding. The lifetime of this equipment strongly depends on the status of the insulation system (the condition of the paper and oil). The correct interpretation of results is very difficult and requires recourse to multiple methods (chemical, electrical, etc.) to assess the state of ageing of the oil-paper insulation. Our purpose is to know the basic phenomena (polarization) in the oil paper insulation system and develop diagnostic method what can indicate this. Out of a lot of diagnostic techniques in the Hungarian and international practice this paper deal with the Recovery Voltage Measurement (RVM). The RVM method was developed in the Budapest University of Technology in the 1970. This measurement provides practical information about the insulation system (e.g. moisture, ageing) based on the Hungarian investigation of the polarization processes.