Automatic current transformer polarity correction

A method of processing current transformer data, performed by an electronic trip unit, includes obtaining first current data based on a first current signal from a first current transformer, second current data based on a second current signal from a second current transformer, and third current data based on a third current signal from a third current transformer. Using the current data, it is determined whether one of the current transformers is connected to the electronic trip unit with an improper polarity. Upon determining that one of the current transformers is connected to the electronic trip unit with an improper polarity, the obtained current data corresponding to the current transformer that is connected with improper polarity is automatically inverted. A ground fault calculation is performed using the automatically inverted current data.