Output characteristics of field sensor used for optical current transformers applied to the flat-shape three-phase bus-bar

The open-air-type optical current transformer is studied for application to three-phase power distribution equipment. To make this type of OCT, laminations of non-oriented Si-Fe sheet used as shielding are tested for the effect of shielding. The linearity of the magneto-optical field sensor used in the OCT is discussed. It is shown that the proposed OCT will allow 0.5% accurate measurements for three-phase AC currents.