Stray flux (leakage or interference flux) in the iron core of DCC due to the primary eccentric bus-bar and the external adjacent current-carrying conductor were calculated by electromagnetic analytical methods. The equivalent relations between the leakage fields and the interference fields were derived. Based on the relations, the effect of leakage fields caused by the eccentric bus-bar on the DCC error can be easily evaluated by the interference fields generated by the neighboring current-carrying conductor, and a new shape of DCC primary coils has been designed.