Failure Testing of Single-Phase Voltage Transformers of Distribution Networks Due to Discharge Phenomena in Insulation

Failures of single-phase voltage transformers applied in distribution networks are investigated. The aim of the study is to determine how to comply with the operating conditions the service instruction of the voltage transformers in the cold climate regions, used protection equipment and to generate recommendations for increasing the operational reliability. To achieve the objective, problems of electric strength temperature dependence investigation, transformer oil chromatographic analysis and transformer operation modes computer simulation are solved. As a result, insulation defects of voltage transformers are identified and localized by chromatographic analysis of oil. A neural network is proposed to identify faults by partial discharge parameters. Practical recommendations are founded to increase the reliability of voltage transformer operation.