Electromagnetic Modeling of a High Voltage Current Transformer

An electromagnetic modeling procedure for a high voltage current transformer is presented. The procedure can be used to estimate all major components of power loss, including loss in the core, windings, and steel tank enclosure. Provision is also made for incorporating the effects of electrical contact resistance. Finite element analysis is used to estimate core and enclosure losses, while winding losses are obtained through simple closed form calculations. Under certain circumstances, the model shows that loss in the enclosure can be greater than that of the transformer core or windings. Discussion of how the model might be used in a thermal analysis to help predict the capability of the current transformer to sustain operation greater than rated capacity will be presented.