Nonlinearity test and compensation of the passive AFOCT's scale factor

Abstract

Abstract-In order to compensate the nonlinear error of passive all-fiber optic current transformers (AFOCT) in the case of large current input, a new method based on the inverse function correction is presented. Taking the feature of the AFOCT's nonlinear response into account, a high-order signal is produced by an analog circuit, thus the scale factor of the AFOCT could be compensated quickly and accurately. Experimental test shows that when the phase difference between the two interference light paths is within the range of 0~20°, the output of the AFOCT could be compensated to maintain the GB/T 20840.8 0.2 accuracy class.