Abridgment of a new high-accuracy current transformer

This paper is presented for the purpose of describing a new method of compensation, by the use of which the ratio and phase-angle errors of current transformers are materially reduced. There are several similar methods now in use, but these methods possess some undesirable features which are not present in the one described in this paper. By the use of this new method, in which a portion of the secondary turns and an auxiliary short-circuited turn enclose a section of the magnetic circuit, the change in ratio and phase angle between light and full load is considerably reduced, resulting in more nearly approaching a constant ratio, and phase-angle characteristics for all values of load. In view of the demand for meter and transformer combinations which must operate satisfactorily over large ranges of current, this is a desirable feature. The overload characteristics of the current transformer are not injured by the use of this method of reducing the transformer errors. The usual insulation between the primary and secondary can readily be maintained, and the use of this compensating feature does not in any way impair the strength of the transformer to withstand over-current shocks. No changes in the physical dimension of the transformer are required by the application of this compensating method.