A study of insulation failure in a high voltage current transformer

The ageing and deterioration of insulation in high voltage (HV) plants have been a source of concerns to utilities. Breakdown of insulation leads to failures of HV equipment. The ageing and eventual failure of insulation in a high voltage current transformer (HVCT) is the subject of investigation in this paper. A lumped parameter model of HVCT is developed. This model is used to study the influence of deteriorating and failed insulation on the state variables of the HVCT. Some possible scenarios that could lead to a CT failure are investigated in this paper. For all the scenarios considered, steady and transient equations relating the state variables of the model have been developed and analyzed. The objectives of these analyses are to establish the behavioural characteristics of the state variables, establish the interactions between these variables, and investigate the possible generations of harmonics under the various scenarios of deteriorating and outright failure of insulation in the CT. The paper concludes with a discussion of the results obtained