The authors prove through mathematical calculation that the primary conductor accentricity make no effect on the output accuracy of the Rogowski coil on the assumption that the coil skeleton is in an ideal structure and the turns density is homogeneous. They manufacture a dozen of Rogowski coils in real production condition for test

and the results show that most of the coils are sensitive to the primary conductor accentricity. This sensitivity can be weakened effectively by additional electromagnetic screen to make the output accuracy of the Rogowski coil satisfy the error tolerance of the current transformer for engineering purpose.