Online Partial Discharge Monitoring and Failure Analysis of a 132 kV Current Transformer

This paper describes how an online partial discharge monitoring system has been used to identify the correlation between network events and the degradation of insulation within an oil filled 132 kV Current Transformer. It will cover 4 months of online Partial Discharge data as well as the failure analysis and dissection of the 132kV current transformer. It will explain the reasoning for a permanent online monitoring system as well as the constraints of outdoor switch yard monitoring. The business case will be discussed, focusing on how the obtained data was used operationally in order to increase safety and reduce the probability of unplanned outages. The paper will focus on correlating increases in partial discharge activity with network and environmental events to determine a relationship between common operational data and events with the inception of partial discharge and insulation breakdown.