Low-cost prototype for the electronically compensation of Current Transformers

In this paper, a novel method for the compensation of commercial current transformers (CTs), based on the insertion of a series analog circuit at the secondary winding is proposed. The method allows the enhancement of existing transformers which can, thus, reach the 0.2 ratio error and a phase error lower than the measurement sensitivity, only by means of the insertion of a low-cost circuit. The feasibility of the method has been preliminarily verified by applying the model of the compensating circuit to the actual signal acquired at the transformer terminals. Successively, the circuit has been realized and applied to a commercial CT. Experimental tests, aiming at assessing the compensation performance, have been conducted by varying the magneto-motive force at both industrial and higher frequencies.